linux-kernel - Re: [PATCH 2/2] drm: bridge: ti-sn65dsi83: Add error recovery mechanism

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Message-ID: <20241028191948.5fd1bd6d@bootlin.com>
Date: Mon, 28 Oct 2024 19:19:48 +0100
From: Herve Codina <herve.codina@...tlin.com>
To: Marek Vasut <marex@...x.de>
Cc: 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>, David Airlie
 <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, Maarten Lankhorst
 <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>,
 Thomas Zimmermann <tzimmermann@...e.de>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Michael Walle <mwalle@...nel.org>,
 dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, Luca Ceresoli <luca.ceresoli@...tlin.com>,
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH 2/2] drm: bridge: ti-sn65dsi83: Add error recovery
 mechanism

On Mon, 28 Oct 2024 15:47:25 +0100
Marek Vasut <marex@...x.de> wrote:

> On 10/28/24 2:52 PM, Herve Codina wrote:
> > Hi Marek,  
> 
> Hi,
> 
> >>> On Sat, 26 Oct 2024 00:53:51 +0200
> >>> Marek Vasut <marex@...x.de> wrote:
> >>>      
> >>>> On 10/24/24 11:55 AM, Herve Codina wrote:  
> >>>>> In some cases observed during ESD tests, the TI SN65DSI83 cannot recover
> >>>>> from errors by itself. A full restart of the bridge is needed in those
> >>>>> cases to have the bridge output LVDS signals again.  
> >>>>
> >>>> I have seen the bridge being flaky sometimes, do you have any more
> >>>> details of what is going on when this irrecoverable error occurs ?  
> >>>
> >>> The panel attached to the bridge goes and stays black. That's the behavior.
> >>> A full reset brings the panel back displaying frames.  
> >> Is there some noticeable change in 0xe0/0xe1/0xe5 registers, esp. 0xe5,
> >> do they indicate the error occurred somehow ?  
> > 
> > 0xe5 register can signal any DSI errors (depending on when the ESD affects
> > the DSI bus) even PLL unlock bit was observed set but we didn't see any
> > relationship between the bits set in 0xe5 register and the recoverable or
> > unrecoverable behavior.
> > 
> > Also, in some cases, reading the register was not even possible (i2c
> > transaction nacked).  
> Oh, wow, I haven't seen that one before. But this is really useful 
> information, can you please add it into the commit message for V2 ?

Yes, I will add this information in v2.

Best regards,
Hervé


-- 
Hervé Codina, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com