Re: [Intel-gfx] [PATCH v2] drm/i915: Limit the number of loops for reading a split 64bit register

2015-09-09 Thread Jani Nikula
On Tue, 08 Sep 2015, Daniel Vetter wrote: > On Tue, Sep 08, 2015 at 02:17:13PM +0100, Chris Wilson wrote: >> In I915_READ64_2x32 we attempt to read a 64bit register using 2 32bit >> reads. Due to the nature of the registers we try to read in this manner, >> they may increment

Re: [Intel-gfx] [PATCH v2] drm/i915: Limit the number of loops for reading a split 64bit register

2015-09-08 Thread Daniel Vetter
On Tue, Sep 08, 2015 at 02:17:13PM +0100, Chris Wilson wrote: > In I915_READ64_2x32 we attempt to read a 64bit register using 2 32bit > reads. Due to the nature of the registers we try to read in this manner, > they may increment between the two instruction (e.g. a timestamp > counter). To keep

[Intel-gfx] [PATCH v2] drm/i915: Limit the number of loops for reading a split 64bit register

2015-09-08 Thread Chris Wilson
In I915_READ64_2x32 we attempt to read a 64bit register using 2 32bit reads. Due to the nature of the registers we try to read in this manner, they may increment between the two instruction (e.g. a timestamp counter). To keep the result accurate, we repeat the read if we detect an overflow (i.e.