[PATCH] drm/panel: kingdisplay-kd097d04: Disable EoTp

[PATCH] drm/panel: kingdisplay-kd097d04: Disable EoTp

[Sebastian Fleer]

Since commit d97e71e44937 ("drm/bridge: synopsys: dw-mipi-dsi: enable EoTp by
default") panel output on an Acer Chromebook Tab 10 (google-dru) is corrupted.
The tablet I use is equipped with a kingdisplay-kd097d04 panel, disabling EoTp
restores the correct functionality.

Fixes: d97e71e44937 ("drm/bridge: synopsys: dw-mipi-dsi: enable EoTp by default")
Signed-off-by: Sebastian Fleer <dev@dwurp.de>
---
 drivers/gpu/drm/panel/panel-kingdisplay-kd097d04.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/panel/panel-kingdisplay-kd097d04.c b/drivers/gpu/drm/panel/panel-kingdisplay-kd097d04.c
index 2fc7b0779b37..893af9b16756 100644
--- a/drivers/gpu/drm/panel/panel-kingdisplay-kd097d04.c
+++ b/drivers/gpu/drm/panel/panel-kingdisplay-kd097d04.c
@@ -359,7 +359,7 @@ static int kingdisplay_panel_probe(struct mipi_dsi_device *dsi)
 	dsi->lanes = 4;
 	dsi->format = MIPI_DSI_FMT_RGB888;
 	dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST |
-			  MIPI_DSI_MODE_LPM;
+			  MIPI_DSI_MODE_LPM | MIPI_DSI_MODE_NO_EOT_PACKET;
 
 	kingdisplay = devm_drm_panel_alloc(&dsi->dev, __typeof(*kingdisplay), base,
 					   &kingdisplay_panel_funcs,
-- 
2.51.2

Re: [PATCH] drm/panel: kingdisplay-kd097d04: Disable EoTp

[Christoph Fritz]

Hi Sebastian

On Tue, 2025-10-28 at 22:38 +0100, Sebastian Fleer wrote:
> Since commit d97e71e44937 ("drm/bridge: synopsys: dw-mipi-dsi: enable EoTp by
> default") panel output on an Acer Chromebook Tab 10 (google-dru) is corrupted.
> The tablet I use is equipped with a kingdisplay-kd097d04 panel, disabling EoTp
> restores the correct functionality.
> 
> Fixes: d97e71e44937 ("drm/bridge: synopsys: dw-mipi-dsi: enable EoTp by default")

Just to clarify: This is not a fix for that commit, it is a fix for the
panel driver itself.

EoTp is the default in Linux, a panel driver cannot enable it, only
disable it.

Commit d97e71e44937 ("drm/bridge: synopsys: dw-mipi-dsi: enable EoTp by
default") fixed a bug in the synopsys dw-mipi-dsi because EoTp was not
enabled there by default.

Enabling EoTp in dw-mipi-dsi revealed an underlying issue in panel-
kingdisplay-kd097d04.

That same issue appears if one would connect this panel to a different
mipi-dsi core (because there EoTp is also enabled by default).

> Signed-off-by: Sebastian Fleer <dev@dwurp.de>
> ---
>  drivers/gpu/drm/panel/panel-kingdisplay-kd097d04.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/panel/panel-kingdisplay-kd097d04.c b/drivers/gpu/drm/panel/panel-kingdisplay-kd097d04.c
> index 2fc7b0779b37..893af9b16756 100644
> --- a/drivers/gpu/drm/panel/panel-kingdisplay-kd097d04.c
> +++ b/drivers/gpu/drm/panel/panel-kingdisplay-kd097d04.c
> @@ -359,7 +359,7 @@ static int kingdisplay_panel_probe(struct mipi_dsi_device *dsi)
>  	dsi->lanes = 4;
>  	dsi->format = MIPI_DSI_FMT_RGB888;
>  	dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST |
> -			  MIPI_DSI_MODE_LPM;
> +			  MIPI_DSI_MODE_LPM | MIPI_DSI_MODE_NO_EOT_PACKET;
>  
>  	kingdisplay = devm_drm_panel_alloc(&dsi->dev, __typeof(*kingdisplay), base,
>  					   &kingdisplay_panel_funcs,

Re: [PATCH] drm/panel: kingdisplay-kd097d04: Disable EoTp

[Sebastian Fleer]

Hi Christoph,

On 10/28/25 23:31, Christoph Fritz wrote:
 > Hi Sebastian
 >
 > On Tue, 2025-10-28 at 22:38 +0100, Sebastian Fleer wrote:
 >> Since commit d97e71e44937 ("drm/bridge: synopsys: dw-mipi-dsi: 
enable EoTp by
 >> default") panel output on an Acer Chromebook Tab 10 (google-dru) is 
corrupted.
 >> The tablet I use is equipped with a kingdisplay-kd097d04 panel, 
disabling EoTp
 >> restores the correct functionality.
 >>
 >> Fixes: d97e71e44937 ("drm/bridge: synopsys: dw-mipi-dsi: enable EoTp 
by default")
 >
 > Just to clarify: This is not a fix for that commit, it is a fix for the
 > panel driver itself.
 >
 > EoTp is the default in Linux, a panel driver cannot enable it, only
 > disable it.
 >
 > Commit d97e71e44937 ("drm/bridge: synopsys: dw-mipi-dsi: enable EoTp by
 > default") fixed a bug in the synopsys dw-mipi-dsi because EoTp was not
 > enabled there by default.
 >
 > Enabling EoTp in dw-mipi-dsi revealed an underlying issue in panel-
 > kingdisplay-kd097d04.
 >
 > That same issue appears if one would connect this panel to a different
 > mipi-dsi core (because there EoTp is also enabled by default).
 >
thanks for your clarification. You're right, this change is merely a 
workaround for the kingdisplay panel.
However, I'm in favor of keeping the "Fixes:" line since using bisect, 
commit d97e71e44937 ("drm/bridge: synopsys: dw-mipi-dsi: enable EoTp by
default") is found as the first commit that shows distorted output for 
that panel.
But I can make the nature of the change more clear in the commit 
message. Would that be OK for you?

Best regards,
Sebastian

 >> Signed-off-by: Sebastian Fleer <dev@dwurp.de>
 >> ---
 >>   drivers/gpu/drm/panel/panel-kingdisplay-kd097d04.c | 2 +-
 >>   1 file changed, 1 insertion(+), 1 deletion(-)
 >>
 >> diff --git a/drivers/gpu/drm/panel/panel-kingdisplay-kd097d04.c 
b/drivers/gpu/drm/panel/panel-kingdisplay-kd097d04.c
 >> index 2fc7b0779b37..893af9b16756 100644
 >> --- a/drivers/gpu/drm/panel/panel-kingdisplay-kd097d04.c
 >> +++ b/drivers/gpu/drm/panel/panel-kingdisplay-kd097d04.c
 >> @@ -359,7 +359,7 @@ static int kingdisplay_panel_probe(struct 
mipi_dsi_device *dsi)
 >>   	dsi->lanes = 4;
 >>   	dsi->format = MIPI_DSI_FMT_RGB888;
 >>   	dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST |
 >> -			  MIPI_DSI_MODE_LPM;
 >> +			  MIPI_DSI_MODE_LPM | MIPI_DSI_MODE_NO_EOT_PACKET;
 >>
 >>   	kingdisplay = devm_drm_panel_alloc(&dsi->dev, 
__typeof(*kingdisplay), base,
 >>   					   &kingdisplay_panel_funcs,

Re: [PATCH] drm/panel: kingdisplay-kd097d04: Disable EoTp

[Christoph Fritz]

>  >> Fixes: d97e71e44937 ("drm/bridge: synopsys: dw-mipi-dsi: enable EoTp 
> by default")

Nitpick: Your Mailclient messed up quoting.

>  >
>  > Just to clarify: This is not a fix for that commit, it is a fix for the
>  > panel driver itself.
>  >
>  > EoTp is the default in Linux, a panel driver cannot enable it, only
>  > disable it.
>  >
>  > Commit d97e71e44937 ("drm/bridge: synopsys: dw-mipi-dsi: enable EoTp by
>  > default") fixed a bug in the synopsys dw-mipi-dsi because EoTp was not
>  > enabled there by default.
>  >
>  > Enabling EoTp in dw-mipi-dsi revealed an underlying issue in panel-
>  > kingdisplay-kd097d04.
>  >
>  > That same issue appears if one would connect this panel to a different
>  > mipi-dsi core (because there EoTp is also enabled by default).
>  >
> thanks for your clarification. You're right, this change is merely a 
> workaround for the kingdisplay panel.

It's not a workaround, it's the actual fix.

> However, I'm in favor of keeping the "Fixes:" line since using bisect, 
> commit d97e71e44937 ("drm/bridge: synopsys: dw-mipi-dsi: enable EoTp by
> default") is found as the first commit that shows distorted output for 
> that panel.

Documentation states:

 || A Fixes: tag indicates that the patch fixes a bug in a previous
 || commit

You are quoting the wrong commit in your Fixes: tag.

Re: [PATCH] drm/panel: kingdisplay-kd097d04: Disable EoTp

[Sebastian Fleer]

On 10/29/25 09:15, Christoph Fritz wrote:
> It's not a workaround, it's the actual fix.
> 
>> However, I'm in favor of keeping the "Fixes:" line since using bisect,
>> commit d97e71e44937 ("drm/bridge: synopsys: dw-mipi-dsi: enable EoTp by
>> default") is found as the first commit that shows distorted output for
>> that panel.
> Documentation states:
> 
>   || A Fixes: tag indicates that the patch fixes a bug in a previous
>   || commit
> 
> You are quoting the wrong commit in your Fixes: tag.

OK, now I got it. I'll send v2 with Fixes: 2a994cbed6b2 ("drm/panel: Add 
Kingdisplay KD097D04 panel driver").

Thank you for your guidance.

Best regards
Sebastian