linux-kernel - Re: [PATCH v2 0/2] drm/bridge: tc358767: Fix DRM_BRIDGE_ATTACH_NO

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Date: Mon, 24 Jun 2024 13:17:25 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Alexander Stein <alexander.stein@...tq-group.com>
Cc: Aradhya Bhatia <a-bhatia1@...com>, dri-devel@...ts.freedesktop.org, 
	Jan Kiszka <jan.kiszka@...mens.com>, Marek Vasut <marex@...x.de>, 
	Tomi Valkeinen <tomi.valkeinen@...asonboard.com>, Andrzej Hajda <andrzej.hajda@...el.com>, 
	Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>, 
	Laurent Pinchart <Laurent.pinchart@...asonboard.com>, Jonas Karlman <jonas@...boo.se>, 
	Jernej Skrabec <jernej.skrabec@...il.com>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>, 
	Sam Ravnborg <sam@...nborg.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/2] drm/bridge: tc358767: Fix DRM_BRIDGE_ATTACH_NO_CONNECTOR
 case

On Mon, 24 Jun 2024 at 13:07, Alexander Stein
<alexander.stein@...tq-group.com> wrote:
>
> Hi,
>
> Am Montag, 24. Juni 2024, 11:49:04 CEST schrieb Dmitry Baryshkov:
> > On Mon, Jun 24, 2024 at 03:07:10PM GMT, Aradhya Bhatia wrote:
> > >
> > >
> > > On 22/06/24 17:49, Dmitry Baryshkov wrote:
> > > > On Sat, Jun 22, 2024 at 05:16:58PM GMT, Aradhya Bhatia wrote:
> > > >>
> > > >>
> > > >> On 17-Jun-24 13:41, Dmitry Baryshkov wrote:
> > > >>> On Mon, Jun 17, 2024 at 07:40:32AM GMT, Jan Kiszka wrote:
> > > >>>> On 16.02.24 15:57, Marek Vasut wrote:
> > > >>>>> On 2/16/24 10:10, Tomi Valkeinen wrote:
> > > >>>>>> Ok. Does anyone have a worry that these patches make the situation
> > > >>>>>> worse for the DSI case than it was before? Afaics, if the DSI lanes
> > > >>>>>> are not set up early enough by the DSI host, the driver would break
> > > >>>>>> with and without these patches.
> > > >>>>>>
> > > >>>>>> These do fix the driver for DRM_BRIDGE_ATTACH_NO_CONNECTOR and DPI, so
> > > >>>>>> I'd like to merge these unless these cause a regression with the DSI
> > > >>>>>> case.
> > > >>>>>
> > > >>>>> 1/2 looks good to me, go ahead and apply .
> > > >>
> > > >> Isn't there any way for the second patch to move forward as well though?
> > > >> The bridge device (under DPI to (e)DP mode) cannot really work without
> > > >> it, and the patches have been pending idle for a long time. =)
> > > >>
> > > >>>>
> > > >>>> My local patches still apply on top of 6.10-rc4, so I don't think this
> > > >>>> ever happened. What's still holding up this long-pending fix (at least
> > > >>>> for our devices)?
> > > >>>
> > > >>> Neither of the patches contains Fixes tags. If the first patch fixes an
> > > >>> issue in previous kernels, please consider following the stable process.
> > > >>>
> > > >>> If we are unsure about the second patch, please send the first patch
> > > >>> separately, adding proper tags.
> > > >>>
> > > >>
> > > >> Thanks Dmitry! I can send the patches again with the required fixes
> > > >> tags (or just patch-1 if we cannot do anything about patch-2).
> > > >
> > > > The problem with the second patch is that it get mixed reviews. I can
> > > > ack the first patch, but for the second one I'd need a confirmation from
> > > > somebody else. I'll go on and apply the first patch later today.
> > > >
> > >
> > > Thanks Dmitry!
> > >
> > > However, would it be okay if I instead add another patch that makes 2
> > > versions of the "tc_edp_bridge_funcs", say "tc_dpi_edp_bridge_funcs" and
> > > "tc_dsi_edp_bridge_funcs", that have all the same function hooks except
> > > for the .edid_read()?
> > >
> > > The dsi edid_read() will remain the same, and Tomi's patch - patch 2/2 -
> > > will only fix the dpi version of the edid_read()?
> > >
> > > The bridge already has the capability to distinguish a DSI input from a
> > > DPI input. This can be leveraged to decide which set of functions need
> > > to be used without any major changes.
> >
> > I'd prefer if somebody with the DSI setup can ack / test the second
> > patch.
> >
> >
>
> Now that my DSI-DP setup works apparently without issue I could test patch 2.
> Since my setup does not use DRM_BRIDGE_ATTACH_NO_CONNECTOR (running on
> drivers/gpu/drm/mxsfb/lcdif_drv.c), I can only say
> there is no regression.

Let me send a (non-tested) patch, switching to drm_bridge_connector,
then you can probably test both of them


-- 
With best wishes
Dmitry