[Intel-gfx] [PATCH 1/2] drm/i915: Enable mmio_debug for vlv/chv

Chris Wilson chris at chris-wilson.co.uk
Fri Jan 8 06:20:49 PST 2016

On Fri, Jan 08, 2016 at 03:51:19PM +0200, Mika Kuoppala wrote:
> With commit 8ac3e1bb76cc ("drm/i915: Add non claimed mmio checking
> for vlv/chv") we now have chv/vlv support in place for detecting
> unclaimed access. Also the perf hit of extra mmio read
> is now only suffered if mmio_debug is set.
> This allows us to stuff the macro for unclaimed reg
> detection inside a generic gen6 register access, as now all
> gens using these macros uses also unclaimed debugs, the one
> exception being snb. We gain more clean and generic macros
> and only downside is that snb will suffer one branch perf hit
> without upside.
> Note that the hsw write path debug register check now
> happens before fifo check, but this should not make
> any real difference.
> As vlv/chv use the generic gen6 access macros, the consequence
> is that they gain the mmio_debug feature.
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Signed-off-by: Mika Kuoppala <mika.kuoppala at intel.com>

I still fancy a GEN6_DBG_READ/WRITE_HEADER but with only a couple of
gen, it doesn't seem worth the argument. (Though we still need to reduce
the expense of ilk_irq_handler, but for the most part that is to avoid
these vfunc altogether.)

Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>

Chris Wilson, Intel Open Source Technology Centre

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