From: Neil Armstrong <narmstrong@baylibre.com>
To: Tomi Valkeinen <tomi.valkeinen@ti.com>,
Andrey Smirnov <andrew.smirnov@gmail.com>
Cc: Andrey Gusakov <andrey.gusakov@cogentembedded.com>,
Chris Healy <cphealy@gmail.com>, Jyri Sarha <jsarha@ti.com>,
dri-devel@lists.freedesktop.org,
Laurent Pinchart <Laurent.pinchart@ideasonboard.com>
Subject: Re: [PATCH] drm/bridge: tc358767: fix poll timeouts
Date: Mon, 10 Feb 2020 10:18:07 +0100 [thread overview]
Message-ID: <eb7dde70-5dec-3d08-06db-abafa2f96e3e@baylibre.com> (raw)
In-Reply-To: <943cfd61-8756-a2f4-5659-1f0335c7ed1e@ti.com>
On 13/01/2020 14:31, Tomi Valkeinen wrote:
> Hi Andrzej,
>
> On 09/12/2019 16:45, Andrey Smirnov wrote:
>> + Chris Healy
>>
>> On Mon, Dec 9, 2019 at 12:27 AM Tomi Valkeinen <tomi.valkeinen@ti.com> wrote:
>>>
>>> Link training fails with:
>>>
>>> Link training timeout waiting for LT_LOOPDONE!
>>> main link enable error: -110
>>>
>>> This is caused by too tight timeouts, which were changed recently in
>>> aa92213f388b ("drm/bridge: tc358767: Simplify polling in tc_link_training()").
>>>
>>> With a quick glance, the commit does not change the timeouts. However,
>>> the method of delaying/sleeping is different, and as the timeout in the
>>> previous implementation was not explicit, the new version in practice
>>> has much tighter timeout.
>>>
>>> The same change was made to other parts in the driver, but the link
>>> training timeout is the only one I have seen causing issues.
>>> Nevertheless, 1 us sleep is not very sane, and the timeouts look pretty
>>> tight, so lets fix all the timeouts.
>>>
>>> One exception was the aux busy poll, where the poll sleep was much
>>> longer than necessary (or optimal).
>>>
>>> I measured the times on my setup, and now the sleep times are set to
>>> such values that they result in multiple loops, but not too many (say,
>>> 5-10 loops). The timeouts were all increased to 100ms, which should be
>>> more than enough for all of these, but in case of bad errors, shouldn't
>>> stop the driver as multi-second timeouts could do.
>>>
>>> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
>>> Fixes: aa92213f388b ("drm/bridge: tc358767: Simplify polling in tc_link_training()")
>>
>> Tested on RDU2 with TC358767/eDP panel, doesn't seem to break anything
>> there, so:
>>
>> Tested-by: Andrey Smirnov <andrew.smirnov@gmail.com>
>
> Andrzej, can you pick this up for -fixes?
>
> Tomi
>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Applied to drm-misc-fixes
Neil
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prev parent reply other threads:[~2020-02-10 9:18 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-09 8:27 [PATCH] drm/bridge: tc358767: fix poll timeouts Tomi Valkeinen
2019-12-09 14:45 ` Andrey Smirnov
2020-01-13 13:31 ` Tomi Valkeinen
2020-02-10 9:18 ` Neil Armstrong [this message]
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