Re: [PATCH 1/2] drm/i915: Remove the MI_FLUSH_ENABLE setting.

[Ben Widawsky <ben@bwidawsk.net>]

On 01/19/2012 10:50 AM, Eric Anholt wrote:
> We have always been using the wrong bit -- it's bit 12.  However, the
> bit also doesn't do anything -- hardware has always accepted the
> MI_FLUSH command even when it was specced not to.
> 
> Given that there is only one MI_FLUSH emitted in all of the driver
> stack on gen6+ (in i965_video.c of the 2d driver, and it should be
> using other code to do its flush instead), just remove the MI_FLUSH
> enable instead of trying to fix it.
> 
> Signed-off-by: Eric Anholt <eric@anholt.net>
> ---
>  drivers/gpu/drm/i915/intel_ringbuffer.c |    2 --
>  1 files changed, 0 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
> index 2df35e3..d21346b 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
> @@ -389,8 +389,6 @@ static int init_render_ring(struct intel_ring_buffer *ring)
>  
>  	if (INTEL_INFO(dev)->gen > 3) {
>  		int mode = VS_TIMER_DISPATCH << 16 | VS_TIMER_DISPATCH;
> -		if (IS_GEN6(dev) || IS_GEN7(dev))
> -			mode |= MI_FLUSH_ENABLE << 16 | MI_FLUSH_ENABLE;
>  		I915_WRITE(MI_MODE, mode);
>  		if (IS_GEN7(dev))
>  			I915_WRITE(GFX_MODE_GEN7,

I'd like to see a tested-by on this with old userspace before pulling
this in. IFF someone does that, r-b me.

Patch 2/2 I still have some gripe with as detailed in that thread.

~Ben