[Intel-gfx] [RFC] drm/i915: Add sysfs entry for reading GPU Timestamp

[Chris Wilson]

On Wed, Sep 24, 2014 at 03:41:08PM +0200, Michał Winiarski wrote:
> Reading timestamp register using I915_READ64 returns incorrect value.
> Unfortunately, that's how I915_REG_READ ioctl is handling it on x86_64,
> resulting in different counter size (we can only get 32 usable bits on
> x86_64 vs 36 bits on x86).
> Propose new sysfs interface for accessing full 36 bits of timestamp in
> architecture independent way (using two consecutive reads).

I've seen lots of patches to avoid fixing the register read. Why?
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre