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

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Date: Mon, 24 Jun 2024 12:07:02 +0200
From: Alexander Stein <alexander.stein@...tq-group.com>
To: Aradhya Bhatia <a-bhatia1@...com>, dri-devel@...ts.freedesktop.org
Cc: 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>, dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Subject: Re: [PATCH v2 0/2] drm/bridge: tc358767: Fix DRM_BRIDGE_ATTACH_NO_CONNECTOR case

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.

Best regards,
Alexander
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