[PATCH] drm/imx/ipuv3: Fix front porch adjustment upon hactive aligning

[PATCH] drm/imx/ipuv3: Fix front porch adjustment upon hactive aligning

[Christian König]

From: Alexander Stein <alexander.stein@ew.tq-group.com>

When hactive is not aligned to 8 pixels, it is aligned accordingly and
hfront porch needs to be reduced the same amount. Unfortunately the front
porch is set to the difference rather than reducing it. There are some
Samsung TVs which can't cope with a front porch of instead of 70.

Fixes: 94dfec48fca7 ("drm/imx: Add 8 pixel alignment fix")
Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Link: https://lore.kernel.org/r/20230515072137.116211-1-alexander.stein@ew.tq-group.com
[p.zabel@pengutronix.de: Fixed subject]
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20230515072137.116211-1-alexander.stein@ew.tq-group.com
---
 drivers/gpu/drm/imx/ipuv3/ipuv3-crtc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/imx/ipuv3/ipuv3-crtc.c b/drivers/gpu/drm/imx/ipuv3/ipuv3-crtc.c
index 5f26090b0c98..89585b31b985 100644
--- a/drivers/gpu/drm/imx/ipuv3/ipuv3-crtc.c
+++ b/drivers/gpu/drm/imx/ipuv3/ipuv3-crtc.c
@@ -310,7 +310,7 @@ static void ipu_crtc_mode_set_nofb(struct drm_crtc *crtc)
 		dev_warn(ipu_crtc->dev, "8-pixel align hactive %d -> %d\n",
 			 sig_cfg.mode.hactive, new_hactive);
 
-		sig_cfg.mode.hfront_porch = new_hactive - sig_cfg.mode.hactive;
+		sig_cfg.mode.hfront_porch -= new_hactive - sig_cfg.mode.hactive;
 		sig_cfg.mode.hactive = new_hactive;
 	}
 
-- 
2.34.1

Re: [PATCH] drm/imx/ipuv3: Fix front porch adjustment upon hactive aligning

[Greg KH]

On Tue, Aug 01, 2023 at 04:53:53PM +0200, Christian König wrote:
> From: Alexander Stein <alexander.stein@ew.tq-group.com>
> 
> When hactive is not aligned to 8 pixels, it is aligned accordingly and
> hfront porch needs to be reduced the same amount. Unfortunately the front
> porch is set to the difference rather than reducing it. There are some
> Samsung TVs which can't cope with a front porch of instead of 70.
> 
> Fixes: 94dfec48fca7 ("drm/imx: Add 8 pixel alignment fix")
> Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
> Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
> Link: https://lore.kernel.org/r/20230515072137.116211-1-alexander.stein@ew.tq-group.com
> [p.zabel@pengutronix.de: Fixed subject]
> Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
> Link: https://patchwork.freedesktop.org/patch/msgid/20230515072137.116211-1-alexander.stein@ew.tq-group.com
> ---
>  drivers/gpu/drm/imx/ipuv3/ipuv3-crtc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)


<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>