On Mon, Feb 04, 2019 at 10:22:32PM +0200, Ville Syrjala wrote: > From: Ville Syrjälä <[email protected]> > > Disabling WM1+ on ICL causes tons of underruns with > linear/X-tiled framebuffers. We can avoid this by flipping > on a chicken bit affecting the way the hw fill the FIFO. > This may not be the final solution but should hopefully > avoid some underruns in the meantime. > > v2: Apparently PIPE_CHICKEN is icl+ only > > Signed-off-by: Ville Syrjälä <[email protected]>
I can't speak for what this register actually does, but your patch accurately implements the recommendation from the hardware guys, so Reviewed-by: Matt Roper <[email protected]> > --- > drivers/gpu/drm/i915/i915_reg.h | 1 + > drivers/gpu/drm/i915/intel_display.c | 6 ++++++ > 2 files changed, 7 insertions(+) > > diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h > index ede54fdc1676..12964b0fbc54 100644 > --- a/drivers/gpu/drm/i915/i915_reg.h > +++ b/drivers/gpu/drm/i915/i915_reg.h > @@ -7618,6 +7618,7 @@ enum { > #define _PIPEB_CHICKEN 0x71038 > #define _PIPEC_CHICKEN 0x72038 > #define PER_PIXEL_ALPHA_BYPASS_EN (1 << 7) > +#define PM_FILL_MAINTAIN_DBUF_FULLNESS (1 << 0) > #define PIPE_CHICKEN(pipe) _MMIO_PIPE(pipe, _PIPEA_CHICKEN,\ > _PIPEB_CHICKEN) > > diff --git a/drivers/gpu/drm/i915/intel_display.c > b/drivers/gpu/drm/i915/intel_display.c > index 5b9b9791d290..b825ceed7f1d 100644 > --- a/drivers/gpu/drm/i915/intel_display.c > +++ b/drivers/gpu/drm/i915/intel_display.c > @@ -3911,6 +3911,12 @@ static void icl_set_pipe_chicken(struct intel_crtc > *crtc) > */ > tmp |= PER_PIXEL_ALPHA_BYPASS_EN; > > + /* > + * W/A for underruns with linear/X-tiled with > + * WM1+ disabled. > + */ > + tmp |= PM_FILL_MAINTAIN_DBUF_FULLNESS; > + > I915_WRITE(PIPE_CHICKEN(pipe), tmp); > } > > -- > 2.19.2 > > _______________________________________________ > Intel-gfx mailing list > [email protected] > https://lists.freedesktop.org/mailman/listinfo/intel-gfx -- Matt Roper Graphics Software Engineer IoTG Platform Enabling & Development Intel Corporation (916) 356-2795 _______________________________________________ Intel-gfx mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/intel-gfx
