Re: [PATCH 3/7] drm/i915/bdw: MI_FLUSH_DW a qword instead of dword

[Ben Widawsky <benjamin.widawsky@intel.com>]

On Mon, Aug 04, 2014 at 11:15:15AM -0700, Rodrigo Vivi wrote:
> From: Ben Widawsky <benjamin.widawsky@intel.com>
> 
> The actual post sync op is "Write Immediate Data QWord." It is therefore
> arguable that we should have always done a qword write.
> 
> The actual impetus for this patch is our decoder complains when we write
> a dword and I was trying to eliminate the spurious errors. With this
> patch, I've noticed a really strange reproducible error turns into a
> different strange reproducible error - so it does indeed have some
> effect of some sort.
> 
> This was also recommended to me by someone that is familiar with the
> Windows driver.
> 
> It's based on top of the semaphore series, so it won't be easily
> applied, I'd guess.
> 
> Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

Did we determine this was needed for anything other than shutting up the
instruction decoder, for debug? Seems like if the existing stuff ain't
broke, don't fix it.

[snip]


-- 
Ben Widawsky, Intel Open Source Technology Center