[Intel-gfx] [PATCH] drm/i915: Correct MI_STORE_DWORD_INDEX usage

[Ben Widawsky]

On Wed, Dec 16, 2015 at 12:18:20AM +0000, Chris Wilson wrote:
> On Tue, Dec 15, 2015 at 04:13:49PM -0800, Ben Widawsky wrote:
> > This has been incorrect since the original commit from Oscar Mateo here:
> > commit 4da46e1e5bb7e7396fad172cdaffbe496562f3d8
> > Author: Oscar Mateo <oscar.mateo at intel.com>
> > Date:   Thu Jul 24 17:04:27 2014 +0100
> > 
> >     drm/i915/bdw: GEN-specific logical ring emit request
> > 
> > The command's offset field is only 10 bits, and this is correct in all the other
> > add_request commands. It's highly likely this this patch makes no functional
> > difference because the hardware will hopefully ignore 31:12 anyway. Technically
> > the existing code is wrong because the docs say the upper bits are MBZ.
> > Ultimately, the patch just clears up the confusion.
> > 
> > NOTE: This patch was compile tested only.
> > NOTE2: The modern docs call it MI_STORE_DATA_INDEX not MI_STORE_DWORD_INDEX
> 
> It doesn't use MI_STORE_DATA_INDEX, but a write to a specific memory
> address (MI_STORE_DWORD_IMM) as it is not storing in the per-context HWS
> but a global (per-engine) page.
> -Chris
> 
> -- 
> Chris Wilson, Intel Open Source Technology Centre

You're right. I just noticed the cmd = MI_STORE_DWORD_IMM_GEN4. Sorry about
that.

-- 
Ben Widawsky, Intel Open Source Technology Center