drivers/gpu/drm/drm_fb_helper.c | 143 ++++++++++++++++++++++++++++++-- 1 file changed, 135 insertions(+), 8 deletions(-)
From: Shixiong Ou <oushixiong@kylinos.cn>
Add fbdev screen extended mode display support
Signed-off-by: Tiger Liu <liuyihu@kylinos.cn>
Signed-off-by: Shixiong Ou <oushixiong@kylinos.cn>
---
drivers/gpu/drm/drm_fb_helper.c | 143 ++++++++++++++++++++++++++++++--
1 file changed, 135 insertions(+), 8 deletions(-)
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 53e9dc0543de..a6ec03bf3aef 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -78,6 +78,17 @@ MODULE_PARM_DESC(drm_leak_fbdev_smem,
"Allow unsafe leaking fbdev physical smem address [default=false]");
#endif
+#define SCREEN_CLONE 0x0
+#define SCREEN_EXPAND_HORIZONTAL 0x1
+#define SCREEN_EXPAND_VERTICAL 0x2
+
+static bool drm_fbdev_screen_expand_mode_enabled;
+static int drm_fbdev_screen_mode = SCREEN_CLONE;
+module_param_named(screen_mode, drm_fbdev_screen_mode, int, 0444);
+MODULE_PARM_DESC(screen_mode,
+ "Screen display of the fbdev. [0 = clone(default), 1 = expand horizontally,"
+ "2 = expand vertically]");
+
static LIST_HEAD(kernel_fb_helper_list);
static DEFINE_MUTEX(kernel_fb_helper_lock);
@@ -1345,15 +1356,35 @@ int drm_fb_helper_set_par(struct fb_info *info)
}
EXPORT_SYMBOL(drm_fb_helper_set_par);
-static void pan_set(struct drm_fb_helper *fb_helper, int dx, int dy)
+static void pan_set_locked(struct drm_client_dev *client,
+ int dx, int dy)
{
struct drm_mode_set *mode_set;
+ int screen_x_offset = dx;
+ int screen_y_offset = dy;
- mutex_lock(&fb_helper->client.modeset_mutex);
- drm_client_for_each_modeset(mode_set, &fb_helper->client) {
- mode_set->x += dx;
- mode_set->y += dy;
+ drm_client_for_each_modeset(mode_set, client) {
+ if (drm_fbdev_screen_expand_mode_enabled) {
+ if (drm_fbdev_screen_mode == SCREEN_EXPAND_HORIZONTAL) {
+ mode_set->x += screen_x_offset;
+ mode_set->y += screen_y_offset;
+ screen_x_offset += mode_set->mode->hdisplay;
+ } else if (drm_fbdev_screen_mode == SCREEN_EXPAND_VERTICAL) {
+ mode_set->x += screen_x_offset;
+ mode_set->y += screen_y_offset;
+ screen_y_offset += mode_set->mode->vdisplay;
+ }
+ } else {
+ mode_set->x = screen_x_offset;
+ mode_set->y = screen_y_offset;
+ }
}
+}
+
+static void pan_set(struct drm_fb_helper *fb_helper, int dx, int dy)
+{
+ mutex_lock(&fb_helper->client.modeset_mutex);
+ pan_set_locked(&fb_helper->client, dx, dy);
mutex_unlock(&fb_helper->client.modeset_mutex);
}
@@ -1387,10 +1418,8 @@ static int pan_display_legacy(struct fb_var_screeninfo *var,
mutex_lock(&client->modeset_mutex);
drm_modeset_lock_all(fb_helper->dev);
+ pan_set_locked(client, var->xoffset, var->yoffset);
drm_client_for_each_modeset(modeset, client) {
- modeset->x = var->xoffset;
- modeset->y = var->yoffset;
-
if (modeset->num_connectors) {
ret = drm_mode_set_config_internal(modeset);
if (!ret) {
@@ -1461,6 +1490,94 @@ static uint32_t drm_fb_helper_find_format(struct drm_fb_helper *fb_helper, const
return DRM_FORMAT_INVALID;
}
+/*
+ * Check if the device supports extended mode
+ *
+ * return true if the device supports extended mode,
+ * otherwise return false.
+ */
+static bool drm_fb_helper_validate_extended_mode(struct drm_fb_helper *fb_helper,
+ struct drm_fb_helper_surface_size *sizes)
+{
+ struct drm_client_dev *client = &fb_helper->client;
+ struct drm_device *dev = fb_helper->dev;
+ struct drm_mode_config *config = &dev->mode_config;
+ struct drm_mode_set *mode_set;
+ u32 crtc_count;
+
+ drm_client_for_each_modeset(mode_set, client) {
+ crtc_count++;
+
+ for (int j = 0; j < mode_set->num_connectors; j++) {
+ struct drm_connector *connector = mode_set->connectors[j];
+
+ if (connector->has_tile) {
+ drm_dbg_kms(client->dev,
+ "Don't support extended with tile mode connector yet\n");
+ return false;
+ }
+ }
+ }
+
+ if (crtc_count < 2) {
+ drm_dbg_kms(client->dev,
+ "Only support extended mode when device have mult-crtcs\n");
+ return false;
+ }
+
+ if (drm_fbdev_screen_mode == SCREEN_EXPAND_HORIZONTAL) {
+ u32 x = 0;
+
+ drm_client_for_each_modeset(mode_set, client) {
+ struct drm_display_mode *desired_mode;
+
+ desired_mode = mode_set->mode;
+ x = mode_set->x;
+ sizes->fb_width = sizes->surface_width += desired_mode->hdisplay;
+ sizes->surface_height =
+ min_t(u32, desired_mode->vdisplay + mode_set->y,
+ sizes->surface_height);
+ sizes->fb_height = min_t(u32, desired_mode->vdisplay + mode_set->y,
+ sizes->fb_height);
+ }
+ sizes->fb_width = sizes->surface_width += x;
+
+ if (sizes->fb_width > config->max_width) {
+ drm_dbg_kms(client->dev,
+ "screen_buffer total width %d > config width %d\n",
+ sizes->fb_width, config->max_width);
+ return false;
+ }
+ } else if (drm_fbdev_screen_mode == SCREEN_EXPAND_VERTICAL) {
+ u32 y = 0;
+
+ drm_client_for_each_modeset(mode_set, client) {
+ struct drm_display_mode *desired_mode;
+
+ desired_mode = mode_set->mode;
+ y = mode_set->y;
+ sizes->fb_height = sizes->surface_height += desired_mode->vdisplay;
+ sizes->surface_width =
+ min_t(u32, desired_mode->hdisplay + mode_set->x,
+ sizes->surface_width);
+ sizes->fb_width = min_t(u32, desired_mode->hdisplay + mode_set->x,
+ sizes->fb_width);
+ }
+ sizes->fb_height = sizes->surface_height += y;
+
+ if (sizes->fb_height > config->max_height) {
+ drm_dbg_kms(client->dev,
+ "screen_buffer_total_height %d > config height %d\n",
+ sizes->fb_height, config->max_height);
+ return false;
+ }
+ } else {
+ return false;
+ }
+
+ return true;
+}
+
static int __drm_fb_helper_find_sizes(struct drm_fb_helper *fb_helper,
struct drm_fb_helper_surface_size *sizes)
{
@@ -1527,6 +1644,16 @@ static int __drm_fb_helper_find_sizes(struct drm_fb_helper *fb_helper,
/* first up get a count of crtcs now in use and new min/maxes width/heights */
crtc_count = 0;
+
+ /* Check if we support extended mode. If we do, we will adjust the sizes accordingly. */
+ if (drm_fbdev_screen_mode &&
+ drm_fb_helper_validate_extended_mode(fb_helper, sizes)) {
+ drm_fbdev_screen_expand_mode_enabled = true;
+ drm_dbg_kms(dev, "Extended mode: horizontal expansion, width: %d, height: %d\n",
+ sizes->surface_width, sizes->surface_height);
+ return 0;
+ }
+
drm_client_for_each_modeset(mode_set, client) {
struct drm_display_mode *desired_mode;
int x, y, j;
--
2.25.1Hi,
kernel test robot noticed the following build warnings:
[auto build test WARNING on drm-misc/drm-misc-next]
[also build test WARNING on linus/master v6.18-rc5 next-20251110]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/oushixiong1025-163-com/drm-fb-helper-add-fbdev-screen-expended-mode-display-support/20251107-172927
base: git://anongit.freedesktop.org/drm/drm-misc drm-misc-next
patch link: https://lore.kernel.org/r/20251107092641.111431-1-oushixiong1025%40163.com
patch subject: [PATCH] drm/fb-helper: add fbdev screen expended mode display support
config: arm-randconfig-003-20251110 (https://download.01.org/0day-ci/archive/20251110/202511102026.2kvJOVYL-lkp@intel.com/config)
compiler: clang version 16.0.6 (https://github.com/llvm/llvm-project 7cbf1a2591520c2491aa35339f227775f4d3adf6)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251110/202511102026.2kvJOVYL-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202511102026.2kvJOVYL-lkp@intel.com/
All warnings (new ones prefixed by >>):
>> drivers/gpu/drm/drm_fb_helper.c:1509:3: warning: variable 'crtc_count' is uninitialized when used here [-Wuninitialized]
crtc_count++;
^~~~~~~~~~
drivers/gpu/drm/drm_fb_helper.c:1506:16: note: initialize the variable 'crtc_count' to silence this warning
u32 crtc_count;
^
= 0
1 warning generated.
vim +/crtc_count +1509 drivers/gpu/drm/drm_fb_helper.c
1492
1493 /*
1494 * Check if the device supports extended mode
1495 *
1496 * return true if the device supports extended mode,
1497 * otherwise return false.
1498 */
1499 static bool drm_fb_helper_validate_extended_mode(struct drm_fb_helper *fb_helper,
1500 struct drm_fb_helper_surface_size *sizes)
1501 {
1502 struct drm_client_dev *client = &fb_helper->client;
1503 struct drm_device *dev = fb_helper->dev;
1504 struct drm_mode_config *config = &dev->mode_config;
1505 struct drm_mode_set *mode_set;
1506 u32 crtc_count;
1507
1508 drm_client_for_each_modeset(mode_set, client) {
> 1509 crtc_count++;
1510
1511 for (int j = 0; j < mode_set->num_connectors; j++) {
1512 struct drm_connector *connector = mode_set->connectors[j];
1513
1514 if (connector->has_tile) {
1515 drm_dbg_kms(client->dev,
1516 "Don't support extended with tile mode connector yet\n");
1517 return false;
1518 }
1519 }
1520 }
1521
1522 if (crtc_count < 2) {
1523 drm_dbg_kms(client->dev,
1524 "Only support extended mode when device have mult-crtcs\n");
1525 return false;
1526 }
1527
1528 if (drm_fbdev_screen_mode == SCREEN_EXPAND_HORIZONTAL) {
1529 u32 x = 0;
1530
1531 drm_client_for_each_modeset(mode_set, client) {
1532 struct drm_display_mode *desired_mode;
1533
1534 desired_mode = mode_set->mode;
1535 x = mode_set->x;
1536 sizes->fb_width = sizes->surface_width += desired_mode->hdisplay;
1537 sizes->surface_height =
1538 min_t(u32, desired_mode->vdisplay + mode_set->y,
1539 sizes->surface_height);
1540 sizes->fb_height = min_t(u32, desired_mode->vdisplay + mode_set->y,
1541 sizes->fb_height);
1542 }
1543 sizes->fb_width = sizes->surface_width += x;
1544
1545 if (sizes->fb_width > config->max_width) {
1546 drm_dbg_kms(client->dev,
1547 "screen_buffer total width %d > config width %d\n",
1548 sizes->fb_width, config->max_width);
1549 return false;
1550 }
1551 } else if (drm_fbdev_screen_mode == SCREEN_EXPAND_VERTICAL) {
1552 u32 y = 0;
1553
1554 drm_client_for_each_modeset(mode_set, client) {
1555 struct drm_display_mode *desired_mode;
1556
1557 desired_mode = mode_set->mode;
1558 y = mode_set->y;
1559 sizes->fb_height = sizes->surface_height += desired_mode->vdisplay;
1560 sizes->surface_width =
1561 min_t(u32, desired_mode->hdisplay + mode_set->x,
1562 sizes->surface_width);
1563 sizes->fb_width = min_t(u32, desired_mode->hdisplay + mode_set->x,
1564 sizes->fb_width);
1565 }
1566 sizes->fb_height = sizes->surface_height += y;
1567
1568 if (sizes->fb_height > config->max_height) {
1569 drm_dbg_kms(client->dev,
1570 "screen_buffer_total_height %d > config height %d\n",
1571 sizes->fb_height, config->max_height);
1572 return false;
1573 }
1574 } else {
1575 return false;
1576 }
1577
1578 return true;
1579 }
1580
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
Am 07.11.25 um 10:26 schrieb oushixiong1025@163.com:
> From: Shixiong Ou <oushixiong@kylinos.cn>
>
> Add fbdev screen extended mode display support
What? What is this about?
>
> Signed-off-by: Tiger Liu <liuyihu@kylinos.cn>
> Signed-off-by: Shixiong Ou <oushixiong@kylinos.cn>
> ---
> drivers/gpu/drm/drm_fb_helper.c | 143 ++++++++++++++++++++++++++++++--
> 1 file changed, 135 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index 53e9dc0543de..a6ec03bf3aef 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -78,6 +78,17 @@ MODULE_PARM_DESC(drm_leak_fbdev_smem,
> "Allow unsafe leaking fbdev physical smem address [default=false]");
> #endif
>
> +#define SCREEN_CLONE 0x0
> +#define SCREEN_EXPAND_HORIZONTAL 0x1
> +#define SCREEN_EXPAND_VERTICAL 0x2
> +
> +static bool drm_fbdev_screen_expand_mode_enabled;
> +static int drm_fbdev_screen_mode = SCREEN_CLONE;
> +module_param_named(screen_mode, drm_fbdev_screen_mode, int, 0444);
> +MODULE_PARM_DESC(screen_mode,
> + "Screen display of the fbdev. [0 = clone(default), 1 = expand horizontally,"
> + "2 = expand vertically]");
> +
> static LIST_HEAD(kernel_fb_helper_list);
> static DEFINE_MUTEX(kernel_fb_helper_lock);
>
> @@ -1345,15 +1356,35 @@ int drm_fb_helper_set_par(struct fb_info *info)
> }
> EXPORT_SYMBOL(drm_fb_helper_set_par);
>
> -static void pan_set(struct drm_fb_helper *fb_helper, int dx, int dy)
> +static void pan_set_locked(struct drm_client_dev *client,
> + int dx, int dy)
> {
> struct drm_mode_set *mode_set;
> + int screen_x_offset = dx;
> + int screen_y_offset = dy;
>
> - mutex_lock(&fb_helper->client.modeset_mutex);
> - drm_client_for_each_modeset(mode_set, &fb_helper->client) {
> - mode_set->x += dx;
> - mode_set->y += dy;
> + drm_client_for_each_modeset(mode_set, client) {
> + if (drm_fbdev_screen_expand_mode_enabled) {
> + if (drm_fbdev_screen_mode == SCREEN_EXPAND_HORIZONTAL) {
> + mode_set->x += screen_x_offset;
> + mode_set->y += screen_y_offset;
> + screen_x_offset += mode_set->mode->hdisplay;
> + } else if (drm_fbdev_screen_mode == SCREEN_EXPAND_VERTICAL) {
> + mode_set->x += screen_x_offset;
> + mode_set->y += screen_y_offset;
> + screen_y_offset += mode_set->mode->vdisplay;
> + }
> + } else {
> + mode_set->x = screen_x_offset;
> + mode_set->y = screen_y_offset;
> + }
> }
> +}
> +
> +static void pan_set(struct drm_fb_helper *fb_helper, int dx, int dy)
> +{
> + mutex_lock(&fb_helper->client.modeset_mutex);
> + pan_set_locked(&fb_helper->client, dx, dy);
> mutex_unlock(&fb_helper->client.modeset_mutex);
> }
>
> @@ -1387,10 +1418,8 @@ static int pan_display_legacy(struct fb_var_screeninfo *var,
>
> mutex_lock(&client->modeset_mutex);
> drm_modeset_lock_all(fb_helper->dev);
> + pan_set_locked(client, var->xoffset, var->yoffset);
> drm_client_for_each_modeset(modeset, client) {
> - modeset->x = var->xoffset;
> - modeset->y = var->yoffset;
> -
> if (modeset->num_connectors) {
> ret = drm_mode_set_config_internal(modeset);
> if (!ret) {
> @@ -1461,6 +1490,94 @@ static uint32_t drm_fb_helper_find_format(struct drm_fb_helper *fb_helper, const
> return DRM_FORMAT_INVALID;
> }
>
> +/*
> + * Check if the device supports extended mode
> + *
> + * return true if the device supports extended mode,
> + * otherwise return false.
> + */
> +static bool drm_fb_helper_validate_extended_mode(struct drm_fb_helper *fb_helper,
> + struct drm_fb_helper_surface_size *sizes)
> +{
> + struct drm_client_dev *client = &fb_helper->client;
> + struct drm_device *dev = fb_helper->dev;
> + struct drm_mode_config *config = &dev->mode_config;
> + struct drm_mode_set *mode_set;
> + u32 crtc_count;
> +
> + drm_client_for_each_modeset(mode_set, client) {
> + crtc_count++;
> +
> + for (int j = 0; j < mode_set->num_connectors; j++) {
> + struct drm_connector *connector = mode_set->connectors[j];
> +
> + if (connector->has_tile) {
> + drm_dbg_kms(client->dev,
> + "Don't support extended with tile mode connector yet\n");
> + return false;
> + }
> + }
> + }
> +
> + if (crtc_count < 2) {
> + drm_dbg_kms(client->dev,
> + "Only support extended mode when device have mult-crtcs\n");
> + return false;
> + }
> +
> + if (drm_fbdev_screen_mode == SCREEN_EXPAND_HORIZONTAL) {
> + u32 x = 0;
> +
> + drm_client_for_each_modeset(mode_set, client) {
> + struct drm_display_mode *desired_mode;
> +
> + desired_mode = mode_set->mode;
> + x = mode_set->x;
> + sizes->fb_width = sizes->surface_width += desired_mode->hdisplay;
> + sizes->surface_height =
> + min_t(u32, desired_mode->vdisplay + mode_set->y,
> + sizes->surface_height);
> + sizes->fb_height = min_t(u32, desired_mode->vdisplay + mode_set->y,
> + sizes->fb_height);
> + }
> + sizes->fb_width = sizes->surface_width += x;
> +
> + if (sizes->fb_width > config->max_width) {
> + drm_dbg_kms(client->dev,
> + "screen_buffer total width %d > config width %d\n",
> + sizes->fb_width, config->max_width);
> + return false;
> + }
> + } else if (drm_fbdev_screen_mode == SCREEN_EXPAND_VERTICAL) {
> + u32 y = 0;
> +
> + drm_client_for_each_modeset(mode_set, client) {
> + struct drm_display_mode *desired_mode;
> +
> + desired_mode = mode_set->mode;
> + y = mode_set->y;
> + sizes->fb_height = sizes->surface_height += desired_mode->vdisplay;
> + sizes->surface_width =
> + min_t(u32, desired_mode->hdisplay + mode_set->x,
> + sizes->surface_width);
> + sizes->fb_width = min_t(u32, desired_mode->hdisplay + mode_set->x,
> + sizes->fb_width);
> + }
> + sizes->fb_height = sizes->surface_height += y;
> +
> + if (sizes->fb_height > config->max_height) {
> + drm_dbg_kms(client->dev,
> + "screen_buffer_total_height %d > config height %d\n",
> + sizes->fb_height, config->max_height);
> + return false;
> + }
> + } else {
> + return false;
> + }
> +
> + return true;
> +}
> +
> static int __drm_fb_helper_find_sizes(struct drm_fb_helper *fb_helper,
> struct drm_fb_helper_surface_size *sizes)
> {
> @@ -1527,6 +1644,16 @@ static int __drm_fb_helper_find_sizes(struct drm_fb_helper *fb_helper,
>
> /* first up get a count of crtcs now in use and new min/maxes width/heights */
> crtc_count = 0;
> +
> + /* Check if we support extended mode. If we do, we will adjust the sizes accordingly. */
> + if (drm_fbdev_screen_mode &&
> + drm_fb_helper_validate_extended_mode(fb_helper, sizes)) {
> + drm_fbdev_screen_expand_mode_enabled = true;
> + drm_dbg_kms(dev, "Extended mode: horizontal expansion, width: %d, height: %d\n",
> + sizes->surface_width, sizes->surface_height);
> + return 0;
> + }
> +
> drm_client_for_each_modeset(mode_set, client) {
> struct drm_display_mode *desired_mode;
> int x, y, j;
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)
在 2025/11/7 18:06, Thomas Zimmermann 写道:
>
>
> Am 07.11.25 um 10:26 schrieb oushixiong1025@163.com:
>> From: Shixiong Ou <oushixiong@kylinos.cn>
>>
>> Add fbdev screen extended mode display support
>
> What? What is this about?
>
If an fbdev device has multiple screens, they are mirrored by default.
This patch aims to enable extended display for the tty, allowing
horizontal or
vertical expansion to achieve a screen splicing effect in the tty terminal.
Best regards,
Shixiong
>>
>> Signed-off-by: Tiger Liu <liuyihu@kylinos.cn>
>> Signed-off-by: Shixiong Ou <oushixiong@kylinos.cn>
>> ---
>> drivers/gpu/drm/drm_fb_helper.c | 143 ++++++++++++++++++++++++++++++--
>> 1 file changed, 135 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_fb_helper.c
>> b/drivers/gpu/drm/drm_fb_helper.c
>> index 53e9dc0543de..a6ec03bf3aef 100644
>> --- a/drivers/gpu/drm/drm_fb_helper.c
>> +++ b/drivers/gpu/drm/drm_fb_helper.c
>> @@ -78,6 +78,17 @@ MODULE_PARM_DESC(drm_leak_fbdev_smem,
>> "Allow unsafe leaking fbdev physical smem address
>> [default=false]");
>> #endif
>> +#define SCREEN_CLONE 0x0
>> +#define SCREEN_EXPAND_HORIZONTAL 0x1
>> +#define SCREEN_EXPAND_VERTICAL 0x2
>> +
>> +static bool drm_fbdev_screen_expand_mode_enabled;
>> +static int drm_fbdev_screen_mode = SCREEN_CLONE;
>> +module_param_named(screen_mode, drm_fbdev_screen_mode, int, 0444);
>> +MODULE_PARM_DESC(screen_mode,
>> + "Screen display of the fbdev. [0 = clone(default), 1 =
>> expand horizontally,"
>> + "2 = expand vertically]");
>> +
>> static LIST_HEAD(kernel_fb_helper_list);
>> static DEFINE_MUTEX(kernel_fb_helper_lock);
>> @@ -1345,15 +1356,35 @@ int drm_fb_helper_set_par(struct fb_info
>> *info)
>> }
>> EXPORT_SYMBOL(drm_fb_helper_set_par);
>> -static void pan_set(struct drm_fb_helper *fb_helper, int dx, int dy)
>> +static void pan_set_locked(struct drm_client_dev *client,
>> + int dx, int dy)
>> {
>> struct drm_mode_set *mode_set;
>> + int screen_x_offset = dx;
>> + int screen_y_offset = dy;
>> - mutex_lock(&fb_helper->client.modeset_mutex);
>> - drm_client_for_each_modeset(mode_set, &fb_helper->client) {
>> - mode_set->x += dx;
>> - mode_set->y += dy;
>> + drm_client_for_each_modeset(mode_set, client) {
>> + if (drm_fbdev_screen_expand_mode_enabled) {
>> + if (drm_fbdev_screen_mode == SCREEN_EXPAND_HORIZONTAL) {
>> + mode_set->x += screen_x_offset;
>> + mode_set->y += screen_y_offset;
>> + screen_x_offset += mode_set->mode->hdisplay;
>> + } else if (drm_fbdev_screen_mode ==
>> SCREEN_EXPAND_VERTICAL) {
>> + mode_set->x += screen_x_offset;
>> + mode_set->y += screen_y_offset;
>> + screen_y_offset += mode_set->mode->vdisplay;
>> + }
>> + } else {
>> + mode_set->x = screen_x_offset;
>> + mode_set->y = screen_y_offset;
>> + }
>> }
>> +}
>> +
>> +static void pan_set(struct drm_fb_helper *fb_helper, int dx, int dy)
>> +{
>> + mutex_lock(&fb_helper->client.modeset_mutex);
>> + pan_set_locked(&fb_helper->client, dx, dy);
>> mutex_unlock(&fb_helper->client.modeset_mutex);
>> }
>> @@ -1387,10 +1418,8 @@ static int pan_display_legacy(struct
>> fb_var_screeninfo *var,
>> mutex_lock(&client->modeset_mutex);
>> drm_modeset_lock_all(fb_helper->dev);
>> + pan_set_locked(client, var->xoffset, var->yoffset);
>> drm_client_for_each_modeset(modeset, client) {
>> - modeset->x = var->xoffset;
>> - modeset->y = var->yoffset;
>> -
>> if (modeset->num_connectors) {
>> ret = drm_mode_set_config_internal(modeset);
>> if (!ret) {
>> @@ -1461,6 +1490,94 @@ static uint32_t
>> drm_fb_helper_find_format(struct drm_fb_helper *fb_helper, const
>> return DRM_FORMAT_INVALID;
>> }
>> +/*
>> + * Check if the device supports extended mode
>> + *
>> + * return true if the device supports extended mode,
>> + * otherwise return false.
>> + */
>> +static bool drm_fb_helper_validate_extended_mode(struct
>> drm_fb_helper *fb_helper,
>> + struct drm_fb_helper_surface_size *sizes)
>> +{
>> + struct drm_client_dev *client = &fb_helper->client;
>> + struct drm_device *dev = fb_helper->dev;
>> + struct drm_mode_config *config = &dev->mode_config;
>> + struct drm_mode_set *mode_set;
>> + u32 crtc_count;
>> +
>> + drm_client_for_each_modeset(mode_set, client) {
>> + crtc_count++;
>> +
>> + for (int j = 0; j < mode_set->num_connectors; j++) {
>> + struct drm_connector *connector = mode_set->connectors[j];
>> +
>> + if (connector->has_tile) {
>> + drm_dbg_kms(client->dev,
>> + "Don't support extended with tile mode
>> connector yet\n");
>> + return false;
>> + }
>> + }
>> + }
>> +
>> + if (crtc_count < 2) {
>> + drm_dbg_kms(client->dev,
>> + "Only support extended mode when device have
>> mult-crtcs\n");
>> + return false;
>> + }
>> +
>> + if (drm_fbdev_screen_mode == SCREEN_EXPAND_HORIZONTAL) {
>> + u32 x = 0;
>> +
>> + drm_client_for_each_modeset(mode_set, client) {
>> + struct drm_display_mode *desired_mode;
>> +
>> + desired_mode = mode_set->mode;
>> + x = mode_set->x;
>> + sizes->fb_width = sizes->surface_width +=
>> desired_mode->hdisplay;
>> + sizes->surface_height =
>> + min_t(u32, desired_mode->vdisplay + mode_set->y,
>> + sizes->surface_height);
>> + sizes->fb_height = min_t(u32, desired_mode->vdisplay +
>> mode_set->y,
>> + sizes->fb_height);
>> + }
>> + sizes->fb_width = sizes->surface_width += x;
>> +
>> + if (sizes->fb_width > config->max_width) {
>> + drm_dbg_kms(client->dev,
>> + "screen_buffer total width %d > config width %d\n",
>> + sizes->fb_width, config->max_width);
>> + return false;
>> + }
>> + } else if (drm_fbdev_screen_mode == SCREEN_EXPAND_VERTICAL) {
>> + u32 y = 0;
>> +
>> + drm_client_for_each_modeset(mode_set, client) {
>> + struct drm_display_mode *desired_mode;
>> +
>> + desired_mode = mode_set->mode;
>> + y = mode_set->y;
>> + sizes->fb_height = sizes->surface_height +=
>> desired_mode->vdisplay;
>> + sizes->surface_width =
>> + min_t(u32, desired_mode->hdisplay + mode_set->x,
>> + sizes->surface_width);
>> + sizes->fb_width = min_t(u32, desired_mode->hdisplay +
>> mode_set->x,
>> + sizes->fb_width);
>> + }
>> + sizes->fb_height = sizes->surface_height += y;
>> +
>> + if (sizes->fb_height > config->max_height) {
>> + drm_dbg_kms(client->dev,
>> + "screen_buffer_total_height %d > config height
>> %d\n",
>> + sizes->fb_height, config->max_height);
>> + return false;
>> + }
>> + } else {
>> + return false;
>> + }
>> +
>> + return true;
>> +}
>> +
>> static int __drm_fb_helper_find_sizes(struct drm_fb_helper *fb_helper,
>> struct drm_fb_helper_surface_size *sizes)
>> {
>> @@ -1527,6 +1644,16 @@ static int __drm_fb_helper_find_sizes(struct
>> drm_fb_helper *fb_helper,
>> /* first up get a count of crtcs now in use and new min/maxes
>> width/heights */
>> crtc_count = 0;
>> +
>> + /* Check if we support extended mode. If we do, we will adjust
>> the sizes accordingly. */
>> + if (drm_fbdev_screen_mode &&
>> + drm_fb_helper_validate_extended_mode(fb_helper, sizes)) {
>> + drm_fbdev_screen_expand_mode_enabled = true;
>> + drm_dbg_kms(dev, "Extended mode: horizontal expansion,
>> width: %d, height: %d\n",
>> + sizes->surface_width, sizes->surface_height);
>> + return 0;
>> + }
>> +
>> drm_client_for_each_modeset(mode_set, client) {
>> struct drm_display_mode *desired_mode;
>> int x, y, j;
>
Hi
Am 10.11.25 um 06:54 schrieb Shixiong Ou:
>
> 在 2025/11/7 18:06, Thomas Zimmermann 写道:
>>
>>
>> Am 07.11.25 um 10:26 schrieb oushixiong1025@163.com:
>>> From: Shixiong Ou <oushixiong@kylinos.cn>
>>>
>>> Add fbdev screen extended mode display support
>>
>> What? What is this about?
>>
> If an fbdev device has multiple screens, they are mirrored by default.
> This patch aims to enable extended display for the tty, allowing
> horizontal or
> vertical expansion to achieve a screen splicing effect in the tty
> terminal.
We won't merge that. The mirroring happens because we cannot easily say
which display is the correct one. But the console is a necessity that we
cannot not provide. Its code is already badly maintained and overly
complicated for what it does. Therefore in the framebuffer console we
want to reduce complexity, not add more.
If you want complex screen layouts, please implement a console in user
space or use a compositor.
Best regards
Thomas
>
> Best regards,
> Shixiong
>
>>>
>>> Signed-off-by: Tiger Liu <liuyihu@kylinos.cn>
>>> Signed-off-by: Shixiong Ou <oushixiong@kylinos.cn>
>>> ---
>>> drivers/gpu/drm/drm_fb_helper.c | 143
>>> ++++++++++++++++++++++++++++++--
>>> 1 file changed, 135 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/drm_fb_helper.c
>>> b/drivers/gpu/drm/drm_fb_helper.c
>>> index 53e9dc0543de..a6ec03bf3aef 100644
>>> --- a/drivers/gpu/drm/drm_fb_helper.c
>>> +++ b/drivers/gpu/drm/drm_fb_helper.c
>>> @@ -78,6 +78,17 @@ MODULE_PARM_DESC(drm_leak_fbdev_smem,
>>> "Allow unsafe leaking fbdev physical smem address
>>> [default=false]");
>>> #endif
>>> +#define SCREEN_CLONE 0x0
>>> +#define SCREEN_EXPAND_HORIZONTAL 0x1
>>> +#define SCREEN_EXPAND_VERTICAL 0x2
>>> +
>>> +static bool drm_fbdev_screen_expand_mode_enabled;
>>> +static int drm_fbdev_screen_mode = SCREEN_CLONE;
>>> +module_param_named(screen_mode, drm_fbdev_screen_mode, int, 0444);
>>> +MODULE_PARM_DESC(screen_mode,
>>> + "Screen display of the fbdev. [0 = clone(default), 1 =
>>> expand horizontally,"
>>> + "2 = expand vertically]");
>>> +
>>> static LIST_HEAD(kernel_fb_helper_list);
>>> static DEFINE_MUTEX(kernel_fb_helper_lock);
>>> @@ -1345,15 +1356,35 @@ int drm_fb_helper_set_par(struct fb_info
>>> *info)
>>> }
>>> EXPORT_SYMBOL(drm_fb_helper_set_par);
>>> -static void pan_set(struct drm_fb_helper *fb_helper, int dx, int dy)
>>> +static void pan_set_locked(struct drm_client_dev *client,
>>> + int dx, int dy)
>>> {
>>> struct drm_mode_set *mode_set;
>>> + int screen_x_offset = dx;
>>> + int screen_y_offset = dy;
>>> - mutex_lock(&fb_helper->client.modeset_mutex);
>>> - drm_client_for_each_modeset(mode_set, &fb_helper->client) {
>>> - mode_set->x += dx;
>>> - mode_set->y += dy;
>>> + drm_client_for_each_modeset(mode_set, client) {
>>> + if (drm_fbdev_screen_expand_mode_enabled) {
>>> + if (drm_fbdev_screen_mode == SCREEN_EXPAND_HORIZONTAL) {
>>> + mode_set->x += screen_x_offset;
>>> + mode_set->y += screen_y_offset;
>>> + screen_x_offset += mode_set->mode->hdisplay;
>>> + } else if (drm_fbdev_screen_mode ==
>>> SCREEN_EXPAND_VERTICAL) {
>>> + mode_set->x += screen_x_offset;
>>> + mode_set->y += screen_y_offset;
>>> + screen_y_offset += mode_set->mode->vdisplay;
>>> + }
>>> + } else {
>>> + mode_set->x = screen_x_offset;
>>> + mode_set->y = screen_y_offset;
>>> + }
>>> }
>>> +}
>>> +
>>> +static void pan_set(struct drm_fb_helper *fb_helper, int dx, int dy)
>>> +{
>>> + mutex_lock(&fb_helper->client.modeset_mutex);
>>> + pan_set_locked(&fb_helper->client, dx, dy);
>>> mutex_unlock(&fb_helper->client.modeset_mutex);
>>> }
>>> @@ -1387,10 +1418,8 @@ static int pan_display_legacy(struct
>>> fb_var_screeninfo *var,
>>> mutex_lock(&client->modeset_mutex);
>>> drm_modeset_lock_all(fb_helper->dev);
>>> + pan_set_locked(client, var->xoffset, var->yoffset);
>>> drm_client_for_each_modeset(modeset, client) {
>>> - modeset->x = var->xoffset;
>>> - modeset->y = var->yoffset;
>>> -
>>> if (modeset->num_connectors) {
>>> ret = drm_mode_set_config_internal(modeset);
>>> if (!ret) {
>>> @@ -1461,6 +1490,94 @@ static uint32_t
>>> drm_fb_helper_find_format(struct drm_fb_helper *fb_helper, const
>>> return DRM_FORMAT_INVALID;
>>> }
>>> +/*
>>> + * Check if the device supports extended mode
>>> + *
>>> + * return true if the device supports extended mode,
>>> + * otherwise return false.
>>> + */
>>> +static bool drm_fb_helper_validate_extended_mode(struct
>>> drm_fb_helper *fb_helper,
>>> + struct drm_fb_helper_surface_size *sizes)
>>> +{
>>> + struct drm_client_dev *client = &fb_helper->client;
>>> + struct drm_device *dev = fb_helper->dev;
>>> + struct drm_mode_config *config = &dev->mode_config;
>>> + struct drm_mode_set *mode_set;
>>> + u32 crtc_count;
>>> +
>>> + drm_client_for_each_modeset(mode_set, client) {
>>> + crtc_count++;
>>> +
>>> + for (int j = 0; j < mode_set->num_connectors; j++) {
>>> + struct drm_connector *connector = mode_set->connectors[j];
>>> +
>>> + if (connector->has_tile) {
>>> + drm_dbg_kms(client->dev,
>>> + "Don't support extended with tile mode
>>> connector yet\n");
>>> + return false;
>>> + }
>>> + }
>>> + }
>>> +
>>> + if (crtc_count < 2) {
>>> + drm_dbg_kms(client->dev,
>>> + "Only support extended mode when device have
>>> mult-crtcs\n");
>>> + return false;
>>> + }
>>> +
>>> + if (drm_fbdev_screen_mode == SCREEN_EXPAND_HORIZONTAL) {
>>> + u32 x = 0;
>>> +
>>> + drm_client_for_each_modeset(mode_set, client) {
>>> + struct drm_display_mode *desired_mode;
>>> +
>>> + desired_mode = mode_set->mode;
>>> + x = mode_set->x;
>>> + sizes->fb_width = sizes->surface_width +=
>>> desired_mode->hdisplay;
>>> + sizes->surface_height =
>>> + min_t(u32, desired_mode->vdisplay + mode_set->y,
>>> + sizes->surface_height);
>>> + sizes->fb_height = min_t(u32, desired_mode->vdisplay +
>>> mode_set->y,
>>> + sizes->fb_height);
>>> + }
>>> + sizes->fb_width = sizes->surface_width += x;
>>> +
>>> + if (sizes->fb_width > config->max_width) {
>>> + drm_dbg_kms(client->dev,
>>> + "screen_buffer total width %d > config width
>>> %d\n",
>>> + sizes->fb_width, config->max_width);
>>> + return false;
>>> + }
>>> + } else if (drm_fbdev_screen_mode == SCREEN_EXPAND_VERTICAL) {
>>> + u32 y = 0;
>>> +
>>> + drm_client_for_each_modeset(mode_set, client) {
>>> + struct drm_display_mode *desired_mode;
>>> +
>>> + desired_mode = mode_set->mode;
>>> + y = mode_set->y;
>>> + sizes->fb_height = sizes->surface_height +=
>>> desired_mode->vdisplay;
>>> + sizes->surface_width =
>>> + min_t(u32, desired_mode->hdisplay + mode_set->x,
>>> + sizes->surface_width);
>>> + sizes->fb_width = min_t(u32, desired_mode->hdisplay +
>>> mode_set->x,
>>> + sizes->fb_width);
>>> + }
>>> + sizes->fb_height = sizes->surface_height += y;
>>> +
>>> + if (sizes->fb_height > config->max_height) {
>>> + drm_dbg_kms(client->dev,
>>> + "screen_buffer_total_height %d > config height
>>> %d\n",
>>> + sizes->fb_height, config->max_height);
>>> + return false;
>>> + }
>>> + } else {
>>> + return false;
>>> + }
>>> +
>>> + return true;
>>> +}
>>> +
>>> static int __drm_fb_helper_find_sizes(struct drm_fb_helper
>>> *fb_helper,
>>> struct drm_fb_helper_surface_size *sizes)
>>> {
>>> @@ -1527,6 +1644,16 @@ static int __drm_fb_helper_find_sizes(struct
>>> drm_fb_helper *fb_helper,
>>> /* first up get a count of crtcs now in use and new
>>> min/maxes width/heights */
>>> crtc_count = 0;
>>> +
>>> + /* Check if we support extended mode. If we do, we will adjust
>>> the sizes accordingly. */
>>> + if (drm_fbdev_screen_mode &&
>>> + drm_fb_helper_validate_extended_mode(fb_helper, sizes)) {
>>> + drm_fbdev_screen_expand_mode_enabled = true;
>>> + drm_dbg_kms(dev, "Extended mode: horizontal expansion,
>>> width: %d, height: %d\n",
>>> + sizes->surface_width, sizes->surface_height);
>>> + return 0;
>>> + }
>>> +
>>> drm_client_for_each_modeset(mode_set, client) {
>>> struct drm_display_mode *desired_mode;
>>> int x, y, j;
>>
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)
© 2016 - 2025 Red Hat, Inc.