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[PATCH v2 3/3] drm/panel-simple: allow LVDS format override

Johannes Zink posted 3 patches 2 years, 8 months ago
There is a newer version of this series
[PATCH v2 3/3] drm/panel-simple: allow LVDS format override
Posted by Johannes Zink 2 years, 8 months ago 
Some panels support multiple LVDS data mapping formats, which can be
used e.g. run displays on jeida-18 format when only 3 LVDS lanes are
available.

Add parsing of an optional data-mapping devicetree property, which also
touches up the bits per color to match the bus format.

Signed-off-by: Johannes Zink <j.zink@pengutronix.de>

---

Changes:

  v1 -> v2: - fix missing unwind goto found by test robot
              Reported-by: kernel test robot <lkp@intel.com>
              Reported-by: Dan Carpenter <error27@gmail.com>
              Link: https://lore.kernel.org/r/202304160359.4LHmFOlU-lkp@intel.com/
---
 drivers/gpu/drm/panel/panel-simple.c | 39 +++++++++++++++++++++++++++++++++++-
 1 file changed, 38 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
index 2a9c1a785a5c..0a35fdb49ccb 100644
--- a/drivers/gpu/drm/panel/panel-simple.c
+++ b/drivers/gpu/drm/panel/panel-simple.c
@@ -40,6 +40,7 @@
 #include <drm/drm_edid.h>
 #include <drm/drm_mipi_dsi.h>
 #include <drm/drm_panel.h>
+#include <drm/drm_of.h>
 
 /**
  * struct panel_desc - Describes a simple panel.
@@ -559,7 +560,7 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
 	struct device_node *ddc;
 	int connector_type;
 	u32 bus_flags;
-	int err;
+	int err, ret;
 
 	panel = devm_kzalloc(dev, sizeof(*panel), GFP_KERNEL);
 	if (!panel)
@@ -605,6 +606,42 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
 			panel_simple_parse_panel_timing_node(dev, panel, &dt);
 	}
 
+
+	/* optional data-mapping property for overriding bus format */
+	ret = drm_of_lvds_get_data_mapping(dev->of_node);
+	if (ret == -EINVAL) {
+		dev_warn(dev, "Ignore invalid data-mapping property");
+	} else if (ret != -ENODEV) {
+		int bpc;
+
+		switch (ret) {
+		default:
+			WARN_ON(1);
+			fallthrough;
+		case MEDIA_BUS_FMT_RGB888_1X7X4_SPWG:
+			fallthrough;
+		case MEDIA_BUS_FMT_RGB888_1X7X4_JEIDA:
+			bpc = 8;
+			break;
+		case MEDIA_BUS_FMT_RGB666_1X7X3_SPWG:
+			bpc = 6;
+		}
+
+		if (desc->bpc != bpc || desc->bus_format != ret) {
+			struct panel_desc *override_desc;
+
+			override_desc = devm_kmemdup(dev, desc, sizeof(*desc), GFP_KERNEL);
+			if (!override_desc) {
+				err = -ENOMEM;
+				goto free_ddc;
+			}
+
+			override_desc->bus_format = ret;
+			override_desc->bpc = bpc;
+			panel->desc = override_desc;
+		}
+	}
+
 	connector_type = desc->connector_type;
 	/* Catch common mistakes for panels. */
 	switch (connector_type) {

-- 
2.39.2
Re: [PATCH v2 3/3] drm/panel-simple: allow LVDS format override
Posted by Laurent Pinchart 2 years, 8 months ago 
Hi Johannes,

Thank you for the patch.

On Tue, May 23, 2023 at 10:19:43AM +0200, Johannes Zink wrote:
> Some panels support multiple LVDS data mapping formats, which can be
> used e.g. run displays on jeida-18 format when only 3 LVDS lanes are
> available.
> 
> Add parsing of an optional data-mapping devicetree property, which also
> touches up the bits per color to match the bus format.

Of course one could argue that the innolux,g101ice-l01 panel should have
used the panel-lvds bindings... :-)

> Signed-off-by: Johannes Zink <j.zink@pengutronix.de>
> 
> ---
> 
> Changes:
> 
>   v1 -> v2: - fix missing unwind goto found by test robot
>               Reported-by: kernel test robot <lkp@intel.com>
>               Reported-by: Dan Carpenter <error27@gmail.com>
>               Link: https://lore.kernel.org/r/202304160359.4LHmFOlU-lkp@intel.com/
> ---
>  drivers/gpu/drm/panel/panel-simple.c | 39 +++++++++++++++++++++++++++++++++++-
>  1 file changed, 38 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
> index 2a9c1a785a5c..0a35fdb49ccb 100644
> --- a/drivers/gpu/drm/panel/panel-simple.c
> +++ b/drivers/gpu/drm/panel/panel-simple.c
> @@ -40,6 +40,7 @@
>  #include <drm/drm_edid.h>
>  #include <drm/drm_mipi_dsi.h>
>  #include <drm/drm_panel.h>
> +#include <drm/drm_of.h>
>  
>  /**
>   * struct panel_desc - Describes a simple panel.
> @@ -559,7 +560,7 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
>  	struct device_node *ddc;
>  	int connector_type;
>  	u32 bus_flags;
> -	int err;
> +	int err, ret;
>  
>  	panel = devm_kzalloc(dev, sizeof(*panel), GFP_KERNEL);
>  	if (!panel)
> @@ -605,6 +606,42 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
>  			panel_simple_parse_panel_timing_node(dev, panel, &dt);
>  	}
>  
> +

Double blank line.

> +	/* optional data-mapping property for overriding bus format */

s/optional/Optional/

> +	ret = drm_of_lvds_get_data_mapping(dev->of_node);
> +	if (ret == -EINVAL) {
> +		dev_warn(dev, "Ignore invalid data-mapping property");
> +	} else if (ret != -ENODEV) {

If someone incorrectly sets the property in DT for a non-LVDS panel,
the result won't be nice. That's of course a DT issue, but I wonder if
we could/should protect against it. You could move this code to a
separate function (which would have the added benefit of lowering the
indentation level as you can return early in error cases), and call it
from panel_simple_probe() only if the panel is an LVDS panel (as
reported by its desc->bus_format value).

> +		int bpc;
> +
> +		switch (ret) {
> +		default:
> +			WARN_ON(1);
> +			fallthrough;
> +		case MEDIA_BUS_FMT_RGB888_1X7X4_SPWG:
> +			fallthrough;
> +		case MEDIA_BUS_FMT_RGB888_1X7X4_JEIDA:
> +			bpc = 8;
> +			break;
> +		case MEDIA_BUS_FMT_RGB666_1X7X3_SPWG:
> +			bpc = 6;
> +		}
> +
> +		if (desc->bpc != bpc || desc->bus_format != ret) {
> +			struct panel_desc *override_desc;
> +
> +			override_desc = devm_kmemdup(dev, desc, sizeof(*desc), GFP_KERNEL);
> +			if (!override_desc) {
> +				err = -ENOMEM;
> +				goto free_ddc;
> +			}
> +
> +			override_desc->bus_format = ret;
> +			override_desc->bpc = bpc;
> +			panel->desc = override_desc;
> +		}
> +	}
> +
>  	connector_type = desc->connector_type;
>  	/* Catch common mistakes for panels. */
>  	switch (connector_type) {

-- 
Regards,

Laurent Pinchart
Re: [PATCH v2 3/3] drm/panel-simple: allow LVDS format override
Posted by Johannes Zink 2 years, 8 months ago 
Hi Laurent,

thanks for your review and your feedback.

On 6/2/23 17:39, Laurent Pinchart wrote:
> Hi Johannes,
> 
> Thank you for the patch.
> 
> On Tue, May 23, 2023 at 10:19:43AM +0200, Johannes Zink wrote:
>> Some panels support multiple LVDS data mapping formats, which can be
>> used e.g. run displays on jeida-18 format when only 3 LVDS lanes are
>> available.
>>
>> Add parsing of an optional data-mapping devicetree property, which also
>> touches up the bits per color to match the bus format.
> 
> Of course one could argue that the innolux,g101ice-l01 panel should have
> used the panel-lvds bindings... :-)

I would prefer to add it in the panel-simple, if ever possible, as this already 
has the timing information etc. in the driver. I would probably opt to use the 
panel-lvds for an entirely new LVDS display, but as the innolux,g101ice-l01 is 
already supported in panel-simple, imho there should be no harm in supporting 
the jeida-18 operating mode as well. Also other displays in panel-simple 
_might_ benefit from supporting non-default LVDS mapping modes, though I have 
not researched whether they have actual hardware support for doing so.

> 
>> Signed-off-by: Johannes Zink <j.zink@pengutronix.de>
>>
>> ---
>>
>> Changes:
>>
>>    v1 -> v2: - fix missing unwind goto found by test robot
>>                Reported-by: kernel test robot <lkp@intel.com>
>>                Reported-by: Dan Carpenter <error27@gmail.com>
>>                Link: https://lore.kernel.org/r/202304160359.4LHmFOlU-lkp@intel.com/
>> ---
>>   drivers/gpu/drm/panel/panel-simple.c | 39 +++++++++++++++++++++++++++++++++++-
>>   1 file changed, 38 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
>> index 2a9c1a785a5c..0a35fdb49ccb 100644
>> --- a/drivers/gpu/drm/panel/panel-simple.c
>> +++ b/drivers/gpu/drm/panel/panel-simple.c
>> @@ -40,6 +40,7 @@
>>   #include <drm/drm_edid.h>
>>   #include <drm/drm_mipi_dsi.h>
>>   #include <drm/drm_panel.h>
>> +#include <drm/drm_of.h>
>>   
>>   /**
>>    * struct panel_desc - Describes a simple panel.
>> @@ -559,7 +560,7 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
>>   	struct device_node *ddc;
>>   	int connector_type;
>>   	u32 bus_flags;
>> -	int err;
>> +	int err, ret;
>>   
>>   	panel = devm_kzalloc(dev, sizeof(*panel), GFP_KERNEL);
>>   	if (!panel)
>> @@ -605,6 +606,42 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
>>   			panel_simple_parse_panel_timing_node(dev, panel, &dt);
>>   	}
>>   
>> +
> 
> Double blank line.

ack, gonna fix in v3.

> 
>> +	/* optional data-mapping property for overriding bus format */
> 
> s/optional/Optional/

ack, gonna fix in v3.

> 
>> +	ret = drm_of_lvds_get_data_mapping(dev->of_node);
>> +	if (ret == -EINVAL) {
>> +		dev_warn(dev, "Ignore invalid data-mapping property");
>> +	} else if (ret != -ENODEV) {
> 
> If someone incorrectly sets the property in DT for a non-LVDS panel,
> the result won't be nice. That's of course a DT issue, but I wonder if
> we could/should protect against it. You could move this code to a
> separate function (which would have the added benefit of lowering the
> indentation level as you can return early in error cases), and call it
> from panel_simple_probe() only if the panel is an LVDS panel (as
> reported by its desc->bus_format value).
> 

that's a good idea, gonna change it for v3.

>> +		int bpc;
>> +
>> +		switch (ret) {
>> +		default:
>> +			WARN_ON(1);
>> +			fallthrough;
>> +		case MEDIA_BUS_FMT_RGB888_1X7X4_SPWG:
>> +			fallthrough;
>> +		case MEDIA_BUS_FMT_RGB888_1X7X4_JEIDA:
>> +			bpc = 8;
>> +			break;
>> +		case MEDIA_BUS_FMT_RGB666_1X7X3_SPWG:
>> +			bpc = 6;
>> +		}
>> +
>> +		if (desc->bpc != bpc || desc->bus_format != ret) {
>> +			struct panel_desc *override_desc;
>> +
>> +			override_desc = devm_kmemdup(dev, desc, sizeof(*desc), GFP_KERNEL);
>> +			if (!override_desc) {
>> +				err = -ENOMEM;
>> +				goto free_ddc;
>> +			}
>> +
>> +			override_desc->bus_format = ret;
>> +			override_desc->bpc = bpc;
>> +			panel->desc = override_desc;
>> +		}
>> +	}
>> +
>>   	connector_type = desc->connector_type;
>>   	/* Catch common mistakes for panels. */
>>   	switch (connector_type) {
> 

-- 
Pengutronix e.K.                | Johannes Zink                  |
Steuerwalder Str. 21            | https://www.pengutronix.de/    |
31137 Hildesheim, Germany       | Phone: +49-5121-206917-0       |
Amtsgericht Hildesheim, HRA 2686| Fax:   +49-5121-206917-5555    |
Re: [PATCH v2 3/3] drm/panel-simple: allow LVDS format override
Posted by Johannes Zink 2 years, 8 months ago 
Hi,

gentle ping here - Do you have any feedback for me on this patch?

Thanks and best regards
Johannes

On 5/23/23 10:19, Johannes Zink wrote:
> Some panels support multiple LVDS data mapping formats, which can be
> used e.g. run displays on jeida-18 format when only 3 LVDS lanes are
> available.
> 
> Add parsing of an optional data-mapping devicetree property, which also
> touches up the bits per color to match the bus format.
> 
> Signed-off-by: Johannes Zink <j.zink@pengutronix.de>
> 
> ---
> 
> Changes:
> 
>    v1 -> v2: - fix missing unwind goto found by test robot
>                Reported-by: kernel test robot <lkp@intel.com>
>                Reported-by: Dan Carpenter <error27@gmail.com>
>                Link: https://lore.kernel.org/r/202304160359.4LHmFOlU-lkp@intel.com/
> ---
>   drivers/gpu/drm/panel/panel-simple.c | 39 +++++++++++++++++++++++++++++++++++-
>   1 file changed, 38 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
> index 2a9c1a785a5c..0a35fdb49ccb 100644
> --- a/drivers/gpu/drm/panel/panel-simple.c
> +++ b/drivers/gpu/drm/panel/panel-simple.c
> @@ -40,6 +40,7 @@
>   #include <drm/drm_edid.h>
>   #include <drm/drm_mipi_dsi.h>
>   #include <drm/drm_panel.h>
> +#include <drm/drm_of.h>
>   
>   /**
>    * struct panel_desc - Describes a simple panel.
> @@ -559,7 +560,7 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
>   	struct device_node *ddc;
>   	int connector_type;
>   	u32 bus_flags;
> -	int err;
> +	int err, ret;
>   
>   	panel = devm_kzalloc(dev, sizeof(*panel), GFP_KERNEL);
>   	if (!panel)
> @@ -605,6 +606,42 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
>   			panel_simple_parse_panel_timing_node(dev, panel, &dt);
>   	}
>   
> +
> +	/* optional data-mapping property for overriding bus format */
> +	ret = drm_of_lvds_get_data_mapping(dev->of_node);
> +	if (ret == -EINVAL) {
> +		dev_warn(dev, "Ignore invalid data-mapping property");
> +	} else if (ret != -ENODEV) {
> +		int bpc;
> +
> +		switch (ret) {
> +		default:
> +			WARN_ON(1);
> +			fallthrough;
> +		case MEDIA_BUS_FMT_RGB888_1X7X4_SPWG:
> +			fallthrough;
> +		case MEDIA_BUS_FMT_RGB888_1X7X4_JEIDA:
> +			bpc = 8;
> +			break;
> +		case MEDIA_BUS_FMT_RGB666_1X7X3_SPWG:
> +			bpc = 6;
> +		}
> +
> +		if (desc->bpc != bpc || desc->bus_format != ret) {
> +			struct panel_desc *override_desc;
> +
> +			override_desc = devm_kmemdup(dev, desc, sizeof(*desc), GFP_KERNEL);
> +			if (!override_desc) {
> +				err = -ENOMEM;
> +				goto free_ddc;
> +			}
> +
> +			override_desc->bus_format = ret;
> +			override_desc->bpc = bpc;
> +			panel->desc = override_desc;
> +		}
> +	}
> +
>   	connector_type = desc->connector_type;
>   	/* Catch common mistakes for panels. */
>   	switch (connector_type) {
> 

-- 
Pengutronix e.K.                | Johannes Zink                  |
Steuerwalder Str. 21            | https://www.pengutronix.de/    |
31137 Hildesheim, Germany       | Phone: +49-5121-206917-0       |
Amtsgericht Hildesheim, HRA 2686| Fax:   +49-5121-206917-5555    |

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