[Intel-gfx] [PATCH] drm/i915/fbc: fix the check for already reserved fbc size

[Jani Nikula]

On Thu, 05 Feb 2015, Ben Widawsky <benjamin.widawsky at intel.com> wrote:
> On Thu, Feb 05, 2015 at 12:04:27PM +0200, Jani Nikula wrote:
>> The check for previously reserved stolen space size for FBC in
>> i915_gem_stolen_setup_compression() did not take the compression
>> threshold into account. Fix this by storing and comparing to
>> uncompressed size instead.
>> 
>> The bug has been introduced in
>> 
>> commit 5e59f7175f96550ede91f58d267d2b551cb6fbba
>> Author: Ben Widawsky <benjamin.widawsky at intel.com>
>> Date:   Mon Jun 30 10:41:24 2014 -0700
>> 
>>     drm/i915: Try harder to get FBC
>> 
>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=88975
>> Suggested-by: Chris Wilson <chris at chris-wilson.co.uk>
>> Cc: Ben Widawsky <benjamin.widawsky at intel.com>
>> Cc: stable at vger.kernel.org # 3.17+
>> Signed-off-by: Jani Nikula <jani.nikula at intel.com>
>
> I guess we can argue semantically about whether or not it was a bug. If I didn't
> put the DRM_INFO there, everything would have continued to work and nobody would
> have complained.

Okay, bug or not, I felt it was unnecessary to be doing the reservation
over and over at every update.

I also contemplated making the logging DRM_INFO_ONCE as a follow-up, but
then thought it's a good canary, at least for now. We occasionally have
these moments where we discover we do some stuff way too often.

> I personally prefer keeping the size as the compressed size
> like you did here: https://bugs.freedesktop.org/show_bug.cgi?id=88975#c1
> but Chris already reviewed this so nuts to me.

As you can tell, I did not really have an opinion one way or the other,
so someone else having an opinion won...


BR,
Jani.



-- 
Jani Nikula, Intel Open Source Technology Center