[Intel-gfx] [PATCH] drm/i915: Retry on every aux read.

Daniel Vetter daniel at ffwll.ch
Tue Oct 20 00:39:18 PDT 2015

On Tue, Oct 20, 2015 at 10:02:21AM +0300, Jani Nikula wrote:
> On Tue, 20 Oct 2015, Rodrigo Vivi <rodrigo.vivi at 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 Vetter
Software Engineer, Intel Corporation

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