[Intel-gfx] [PATCH] drm/dp: Increase link status size

[Ville Syrjälä]

On Tue, Oct 29, 2019 at 03:32:41PM +0200, Jani Nikula wrote:
> On Tue, 29 Oct 2019, Thierry Reding <thierry.reding at gmail.com> wrote:
> > From: Thierry Reding <treding at nvidia.com>
> >
> > The current link status contains bytes 0x202 through 0x207, but we also
> > want to make sure to include the DP_ADJUST_REQUEST_POST_CURSOR2 (0x20c)
> > so that the post-cursor adjustment can be queried during link training.
> 
> We don't currently use this in i915 (we probably should)

IIRC post cursor2 is already deprecated.

> , so the impact
> here is that we'll just read more DPCD than before. I quickly perused
> i915, and this does not appear to directly break anything. I think the
> change is probably fine, but at the same time it freaks me out a bit...
> 
> If you don't mind, please resend this with Cc:
> intel-gfx at lists.freedesktop.org to have our CI crunch through it across
> a number of platforms. Would give me a warm fuzzy feeling. :)
> 
> With the caveat that I didn't look at any other drivers besides i915,
> 
> Reviewed-by: Jani Nikula <jani.nikula at intel.com>
> 
> 
> >
> > Reported-by: coverity-bot <keescook+coverity-bot at chromium.org>
> > Addresses-Coverity-ID: 1487366 ("Memory - corruptions")
> > Fixes: 79465e0ffeb9 ("drm/dp: Add helper to get post-cursor adjustments")
> > Signed-off-by: Thierry Reding <treding at nvidia.com>
> > ---
> > I vaguely recall once carrying a patch to do this, but I can't find any
> > trace of it.
> >
> >  include/drm/drm_dp_helper.h | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
> > index 51ecb5112ef8..9581dec900ba 100644
> > --- a/include/drm/drm_dp_helper.h
> > +++ b/include/drm/drm_dp_helper.h
> > @@ -1121,7 +1121,7 @@
> >  #define DP_MST_PHYSICAL_PORT_0 0
> >  #define DP_MST_LOGICAL_PORT_0 8
> >  
> > -#define DP_LINK_STATUS_SIZE	   6
> > +#define DP_LINK_STATUS_SIZE	   11
> >  bool drm_dp_channel_eq_ok(const u8 link_status[DP_LINK_STATUS_SIZE],
> >  			  int lane_count);
> >  bool drm_dp_clock_recovery_ok(const u8 link_status[DP_LINK_STATUS_SIZE],
> 
> -- 
> Jani Nikula, Intel Open Source Graphics Center
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-- 
Ville Syrjälä
Intel