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Message-ID: <36128d71-a600-4c33-97f6-e694e493b3ee@linux.dev>
Date: Tue, 22 Oct 2024 22:55:38 +0530
From: Aradhya Bhatia <aradhya.bhatia@...ux.dev>
To: Devarsh Thakkar <devarsht@...com>,
Tomi Valkeinen <tomi.valkeinen@...asonboard.com>,
Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
Laurent Pinchart <laurent.pinchart@...asonboard.com>,
Andrzej Hajda <andrzej.hajda@...el.com>,
Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>,
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>, Simona Vetter <simona@...ll.ch>
Cc: Dominik Haller <d.haller@...tec.de>, Sam Ravnborg <sam@...nborg.org>,
Kieran Bingham <kieran.bingham+renesas@...asonboard.com>,
Nishanth Menon <nm@...com>, Vignesh Raghavendra <vigneshr@...com>,
Praneeth Bajjuri <praneeth@...com>, Udit Kumar <u-kumar1@...com>,
Jayesh Choudhary <j-choudhary@...com>,
DRI Development List <dri-devel@...ts.freedesktop.org>,
Linux Kernel List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 07/13] drm/bridge: cdns-dsi: Wait for Clk and Data
Lanes to be ready
On 22/10/24 11:55, Devarsh Thakkar wrote:
> Hi Aradhya,
>
> Thanks for the patch.
>
> On 20/10/24 01:24, Aradhya Bhatia wrote:
>> From: Aradhya Bhatia <a-bhatia1@...com>
>
> [...]
>
>> + /*
>> + * Now that the DSI Link and DSI Phy are initialized,
>> + * wait for the CLK and Data Lanes to be ready.
>> + */
>> + tmp = CLK_LANE_RDY;
>> + for (int i = 0; i < nlanes; i++)
>> + tmp |= DATA_LANE_RDY(i);
>> +
>> + if (readl_poll_timeout(dsi->regs + MCTL_MAIN_STS, status,
>> + status & tmp, 100, 500000))
>
> The above would mark the condition as true even if one data lane gets ready. I
> think we need to poll until all data lanes are marked as ready. Also good to
> give a warning in case we time out.
>
> IMHO below should fix this:
> WARN_ON_ONCE(readl_poll_timeout(dsi->regs + MCTL_MAIN_STS, status,
> (tmp == (status & tmp)), 100, 0));
>
That's how the condition should be, yes! Thanks for the catch!
I would still prefer to keep dev_err instead of WARN_ON_ONCE, because
the latter stack-dumps during boot once, and then can never be seen
again during multiple modesets. The noise in the dmesg is not worth
the issue either.
With dev_err, it can show a clear print once every time it times out.
--
Regards
Aradhya
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