Re: [Intel-gfx] [PATCH 3/5] drm/i915/perf: avoid read back of head register

2017-01-25 Thread Matthew Auld
On 24 January 2017 at 01:25, Robert Bragg wrote: > There's no need for the driver to keep reading back the head pointer > from hardware since the hardware doesn't update it automatically. This > way we can treat any invalid head pointer value as a software/driver > bug

[Intel-gfx] [PATCH 3/5] drm/i915/perf: avoid read back of head register

2017-01-23 Thread Robert Bragg
There's no need for the driver to keep reading back the head pointer from hardware since the hardware doesn't update it automatically. This way we can treat any invalid head pointer value as a software/driver bug instead of spurious hardware behaviour. This change is also a small stepping stone