From: Daniel Vetter <daniel@ffwll.ch>
To: Jani Nikula <jani.nikula@linux.intel.com>
Cc: intel-gfx@lists.freedesktop.org, Rodrigo Vivi <rodrigo.vivi@intel.com>
Subject: Re: [PATCH] drm/i915: Retry on every aux read.
Date: Tue, 20 Oct 2015 09:39:18 +0200 [thread overview]
Message-ID: <20151020073918.GR13786@phenom.ffwll.local> (raw)
In-Reply-To: <877fmiyqde.fsf@intel.com>
On Tue, Oct 20, 2015 at 10:02:21AM +0300, Jani Nikula wrote:
> On Tue, 20 Oct 2015, Rodrigo Vivi <rodrigo.vivi@intel.com> wrote:
> > We have an inconsistency on our code on using intel_dp_dpcd_read_wake with
> > retries and when using drm_dp_dpcd_read helper without retry.
>
> We're supposed to do the retries when the sink may be in a power down
> state. We're not very good at tracking that, and we've cargo culted the
> retry variants all over the place without thinking. This is why we're
> inconsistent.
>
> > Since the retries help in many cases let's be consistent and be on
> > the safe side retrying on every aux read, including i2c ones.
>
> Please let's not add superfluous retries at different levels of the
> stack just to be safe. It's like a variant of the C programmer's
> disease.
>
> If the retries really help [citation needed] we need to figure out what
> we're doing wrong and where, and preferrably fix this at the DP helper
> level for all drivers, if possible.
Yeah, same comment as I've done last time around. If we need this, we need
to do this in core dp helpers.
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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next prev parent reply other threads:[~2015-10-20 7:39 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-20 23:12 [PATCH] drm/i915: Use dpcd read wake for sink crc calls Rodrigo Vivi
2015-08-20 23:23 ` Rodrigo Vivi
2015-08-24 4:57 ` Jindal, Sonika
2015-08-24 19:54 ` Zanoni, Paulo R
2015-08-24 21:20 ` Vivi, Rodrigo
2015-10-21 18:31 ` Thulasimani, Sivakumar
2015-10-21 19:59 ` Vivi, Rodrigo
2015-10-21 20:14 ` Damien Lespiau
2015-10-22 3:26 ` Thulasimani, Sivakumar
2015-11-16 16:05 ` Rodrigo Vivi
2015-11-17 14:08 ` Daniel Vetter
2015-11-18 18:31 ` Vivi, Rodrigo
2015-11-19 9:12 ` Daniel Vetter
2015-08-26 9:06 ` Daniel Vetter
2015-08-26 16:41 ` Vivi, Rodrigo
2015-08-27 9:21 ` Daniel Vetter
2015-08-27 10:45 ` Jani Nikula
2015-10-19 23:08 ` [PATCH] drm/i915: Retry on every aux read Rodrigo Vivi
2015-10-20 7:02 ` Jani Nikula
2015-10-20 7:39 ` Daniel Vetter [this message]
2015-10-20 15:36 ` Vivi, Rodrigo
2015-10-20 17:45 ` Vivi, Rodrigo
2015-10-20 18:31 ` Daniel Vetter
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