sn65dsi83.c: fix dual-channel LVDS output also divide porches

[PATCH] sn65dsi83.c: fix dual-channel LVDS output also divide porches

Posted by Bauer, Markus 1 year, 2 months ago

sn65dsi83.c: fix dual-channel LVDS output also divide porches

When generating dual-channel LVDS to a single display, the
horizontal part has to be divided in halves for each channel.
This was done correctly for hactive, but not for the porches.

Of course this does only apply to sn65dsi84, which is also covered
by this driver.

Cc: stable@vger.kernel.org
Signed-off-by: Markus Bauer <markus.bauer2@avnet.com>
---
 drivers/gpu/drm/bridge/ti-sn65dsi83.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi83.c b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
index ad73f69d768d..d71f752e79ec 100644
--- a/drivers/gpu/drm/bridge/ti-sn65dsi83.c
+++ b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
@@ -399,7 +399,7 @@ static void sn65dsi83_atomic_pre_enable(struct drm_bridge *bridge,
 	unsigned int pval;
 	__le16 le16val;
 	u16 val;
-	int ret;
+	int ret, hfront, hback;
 
 	ret = regulator_enable(ctx->vcc);
 	if (ret) {
@@ -521,12 +521,22 @@ static void sn65dsi83_atomic_pre_enable(struct drm_bridge *bridge,
 	le16val = cpu_to_le16(mode->vsync_end - mode->vsync_start);
 	regmap_bulk_write(ctx->regmap, REG_VID_CHA_VSYNC_PULSE_WIDTH_LOW,
 			  &le16val, 2);
+
+	hback = mode->htotal - mode->hsync_end;
+	if (ctx->lvds_dual_link)
+		hback /= 2;
+
 	regmap_write(ctx->regmap, REG_VID_CHA_HORIZONTAL_BACK_PORCH,
-		     mode->htotal - mode->hsync_end);
+		     hback);
 	regmap_write(ctx->regmap, REG_VID_CHA_VERTICAL_BACK_PORCH,
 		     mode->vtotal - mode->vsync_end);
+
+	hfront = mode->hsync_start - mode->hdisplay;
+	if (ctx->lvds_dual_link)
+		hfront /= 2;
+
 	regmap_write(ctx->regmap, REG_VID_CHA_HORIZONTAL_FRONT_PORCH,
-		     mode->hsync_start - mode->hdisplay);
+		     hfront);
 	regmap_write(ctx->regmap, REG_VID_CHA_VERTICAL_FRONT_PORCH,
 		     mode->vsync_start - mode->vdisplay);
 	regmap_write(ctx->regmap, REG_VID_CHA_TEST_PATTERN, 0x00);
-- 
2.34.1


--
Markus Bauer

Avnet Embedded is becoming TRIA:
www.tria-technologies.com



We continuously commit to comply with the applicable data protection laws and ensure fair and transparent processing of your personal data. 
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Re: [PATCH] sn65dsi83.c: fix dual-channel LVDS output also divide porches

Posted by Dmitry Baryshkov 1 year, 2 months ago

On Tue, Nov 26, 2024 at 09:42:45AM +0000, Bauer, Markus wrote:
> sn65dsi83.c: fix dual-channel LVDS output also divide porches

Please use drm/bridge: ti-sn65dsi83: as subject prefix. Drop the first
line of the commit message.

> 
> When generating dual-channel LVDS to a single display, the
> horizontal part has to be divided in halves for each channel.
> This was done correctly for hactive, but not for the porches.

I don't see this being handled for hactive. Could you please point out
the code?

> 
> Of course this does only apply to sn65dsi84, which is also covered
> by this driver.
> 
> Cc: stable@vger.kernel.org

Also:

Fixes: ceb515ba29ba ("drm/bridge: ti-sn65dsi83: Add TI SN65DSI83 and SN65DSI84 driver")

> Signed-off-by: Markus Bauer <markus.bauer2@avnet.com>
> ---
>  drivers/gpu/drm/bridge/ti-sn65dsi83.c | 16 +++++++++++++---
>  1 file changed, 13 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi83.c b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> index ad73f69d768d..d71f752e79ec 100644
> --- a/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> @@ -399,7 +399,7 @@ static void sn65dsi83_atomic_pre_enable(struct drm_bridge *bridge,
>  	unsigned int pval;
>  	__le16 le16val;
>  	u16 val;
> -	int ret;
> +	int ret, hfront, hback;
>  
>  	ret = regulator_enable(ctx->vcc);
>  	if (ret) {
> @@ -521,12 +521,22 @@ static void sn65dsi83_atomic_pre_enable(struct drm_bridge *bridge,
>  	le16val = cpu_to_le16(mode->vsync_end - mode->vsync_start);
>  	regmap_bulk_write(ctx->regmap, REG_VID_CHA_VSYNC_PULSE_WIDTH_LOW,
>  			  &le16val, 2);
> +
> +	hback = mode->htotal - mode->hsync_end;
> +	if (ctx->lvds_dual_link)
> +		hback /= 2;
> +
>  	regmap_write(ctx->regmap, REG_VID_CHA_HORIZONTAL_BACK_PORCH,
> -		     mode->htotal - mode->hsync_end);
> +		     hback);
>  	regmap_write(ctx->regmap, REG_VID_CHA_VERTICAL_BACK_PORCH,
>  		     mode->vtotal - mode->vsync_end);
> +
> +	hfront = mode->hsync_start - mode->hdisplay;
> +	if (ctx->lvds_dual_link)
> +		hfront /= 2;
> +
>  	regmap_write(ctx->regmap, REG_VID_CHA_HORIZONTAL_FRONT_PORCH,
> -		     mode->hsync_start - mode->hdisplay);
> +		     hfront);
>  	regmap_write(ctx->regmap, REG_VID_CHA_VERTICAL_FRONT_PORCH,
>  		     mode->vsync_start - mode->vdisplay);
>  	regmap_write(ctx->regmap, REG_VID_CHA_TEST_PATTERN, 0x00);
> -- 
> 2.34.1
> 
> 
> --
> Markus Bauer
> 
> Avnet Embedded is becoming TRIA:
> www.tria-technologies.com
> 
> 
> 
> We continuously commit to comply with the applicable data protection laws and ensure fair and transparent processing of your personal data. 
> Please read our privacy statement including an information notice and data protection policy for detailed information on our website.

-- 
With best wishes
Dmitry