[Intel-gfx] [PATCH] drm/i915/gt: Clear the whole first page of LRC on gen9

[Chris Wilson]

Quoting Mika Kuoppala (2020-01-21 13:44:22)
> Chris Wilson <chris at chris-wilson.co.uk> writes:
> 
> > Try clearing the whole first page of the LRC on gen9, just in case HW
> 
> First page of LRC is a bit misleading as this is first page of
> LRC registers and techincally first page of LRC would be hwsp?

I refer to the "Logical Ring" :)

> So,
> 
> s/LRC/LRC register state
> 
> > tries peeking at the poisoned data.
> >
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/gt/intel_lrc.c | 16 ++++++++--------
> >  1 file changed, 8 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
> > index 2d6b41e66b16..bf0c5a998428 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_lrc.c
> > +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
> > @@ -549,7 +549,7 @@ static void set_offsets(u32 *regs,
> >       }
> >  
> >       if (clear) {
> > -             u8 count = *++data;
> > +             unsigned int count = *++data * 16u;
> 
> Nitpick: const 
> 
> >  
> >               /* Clear past the tail for HW access */
> >               GEM_BUG_ON(dword_in_page(regs) > count);
> 
> You might want to add also check that you dont write past page.
> As this seems to be always confined inside a page.
> 
> No other complaints, and above are minor so
> 
> Reviewed-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>

It didn't stop gen9 from eating the poison, so something else is afoot.
-Chris