linux-kernel - Re: [PATCH] drm/panel: jdi-fhd-r63452: move DCS off commands to disable

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Message-ID: <kjlcqkfipct4d54hrtmwdsrifxvuq3qocv5bcmwsufrbxtvvq2@52grw5ijqx4k>
Date: Fri, 10 May 2024 21:02:04 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Barnabás Czémán <trabarni@...il.com>
Cc: Neil Armstrong <neil.armstrong@...aro.org>, 
	Jessica Zhang <quic_jesszhan@...cinc.com>, Sam Ravnborg <sam@...nborg.org>, 
	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>, dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/panel: jdi-fhd-r63452: move DCS off commands to
 disable

On Fri, May 10, 2024 at 09:10:34AM +0200, Barnabás Czémán wrote:
> On Fri, May 10, 2024 at 8:46 AM Barnabás Czémán <trabarni@...il.com> wrote:
> >
> > On Fri, May 10, 2024 at 2:56 AM Dmitry Baryshkov
> > <dmitry.baryshkov@...aro.org> wrote:
> > >
> > > On Thu, May 09, 2024 at 08:14:07PM +0200, Barnabás Czémán wrote:
> > > > Move DCS off commands from .unprepare to .disable so that they
> > > > actually reach the DSI host.
> > > >
> > > > Signed-off-by: Barnabás Czémán <trabarni@...il.com>
> > > > ---
> > > >  drivers/gpu/drm/panel/panel-jdi-fhd-r63452.c | 12 ++++++++++--
> > > >  1 file changed, 10 insertions(+), 2 deletions(-)
> > >
> > > I don't think this is correct. If the driver sends enable commands in
> > > prepare, it should be able to send commands during unprepare too.
> > >
> > It cannot send commands in unprepare, there are multiple panel drivers
> > what do the same.
> > Every panel drivers which have DCS commands to be sent in unprepare
> > has similar error messages with mdp5/dpu.
> >
> > [   92.322564] panel-td4320-boeplus c994000.dsi.0: sending command
> > 0x28 failed: -22
> > [   92.322635] panel-td4320-boeplus c994000.dsi.0: Failed to
> > un-initialize panel: -22
> >
> >
> Here is the error messages, these are comes from unprepare by every panel off:
> [  121.295290] panel-jdi-fhd-r63452 994000.dsi.0: transmit data failed: -22
> [  121.295368] panel-jdi-fhd-r63452 994000.dsi.0: Failed to
> un-initialize panel: -22
> [  184.783019] panel-jdi-fhd-r63452 994000.dsi.0: transmit data failed: -22
> [  184.783066] panel-jdi-fhd-r63452 994000.dsi.0: Failed to
> un-initialize panel: -22
> with this patch these errors no more.
> .prepare works because of this flag ctx->panel.prepare_prev_first = true;

The flag should also invert the order of post_disable chain. It well
might be that the drm/msm/dsi driver shuts down the DSI link too soon.
Please consider fixing the MSM DSI driver instead.

-- 
With best wishes
Dmitry