Re: [PATCH v2 15/29] drm/bridge/synopsys: dw-hdmi: Enable workaround for v2.12a

From: Laurent Pinchart
Date: Tue Oct 09 2018 - 13:40:49 EST

Hi Jernej,

Thank you for the patch.

On Sunday, 7 October 2018 12:38:51 EEST Jernej Skrabec wrote:
> It turns out that even new DW HDMI controllers exhibits same magenta
> line issues as older versions.
> Enable workaround for v2.12a.

This doesn't affect the platforms I maintain, so I can't really test this, but
I'm wondering whether there could be other platforms using a v2.12a DW HDMI
that wouldn't need the workaround.

My platforms use a previous version, namely v2.01a. The workaround for that
version has been enabled by

commit 9c305eb442f3b371fc722ade827bbf673514123e
Author: Neil Armstrong <narmstrong@xxxxxxxxxxxx>
Date: Fri Feb 23 12:44:37 2018 +0100

drm: bridge: dw-hdmi: Fix overflow workaround for Amlogic Meson GX SoCs

I haven't paid too much attention to the patch back then, and have now double-
checked the HDMI output on R-Car Gen3. Enabling the workaround doesn't cause
any regression, and reverting the commit doesn't cause any issue either. I
thus wonder whether we shouldn't enable the workaround with count = 1 in the
default case instead of adding new IP core versions to the list. It would be
nice if someone from Synopsys could comment on this.

> Reviewed-by: Chen-Yu Tsai <wens@xxxxxxxx>
> Signed-off-by: Jernej Skrabec <jernej.skrabec@xxxxxxxx>
> ---
> drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 1 +
> 1 file changed, 1 insertion(+)
> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c index
> 5971976284bf..df1c7a2d6961 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> @@ -1664,6 +1664,7 @@ static void dw_hdmi_clear_overflow(struct dw_hdmi
> *hdmi) case 0x131a:
> case 0x132a:
> case 0x201a:
> + case 0x212a:
> count = 1;
> break;
> default:


Laurent Pinchart