From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mika Kuoppala Subject: Re: [PATCH] drm/i915/fbc: Disable fbc with VT-d also with kbl and cfl Date: Wed, 26 Sep 2018 15:56:39 +0300 Message-ID: <87va6sl8mw.fsf@gaia.fi.intel.com> References: <20180925133803.23677-1-mika.kuoppala@linux.intel.com> <20180925151552.GJ9144@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT Return-path: In-Reply-To: <20180925151552.GJ9144@intel.com> Sender: stable-owner@vger.kernel.org To: Ville =?utf-8?B?U3lyasOkbMOk?= Cc: intel-gfx@lists.freedesktop.org, Paulo Zanoni , Chris Wilson , Rodrigo Vivi , stable@vger.kernel.org List-Id: intel-gfx@lists.freedesktop.org Ville Syrjälä writes: > On Tue, Sep 25, 2018 at 04:38:03PM +0300, Mika Kuoppala wrote: >> Using fbc with VT-d flickers also on kbl and cfl. >> >> Cc: Paulo Zanoni >> Cc: Ville Syrjälä >> Cc: Chris Wilson >> Cc: Rodrigo Vivi >> Cc: # v4.9+ >> Signed-off-by: Mika Kuoppala >> --- >> drivers/gpu/drm/i915/intel_fbc.c | 5 +++-- >> 1 file changed, 3 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c >> index 74d425c700ef..a149f08c1b79 100644 >> --- a/drivers/gpu/drm/i915/intel_fbc.c >> +++ b/drivers/gpu/drm/i915/intel_fbc.c >> @@ -1275,9 +1275,10 @@ static int intel_sanitize_fbc_option(struct drm_i915_private *dev_priv) >> >> static bool need_fbc_vtd_wa(struct drm_i915_private *dev_priv) >> { >> - /* WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl,bxt */ >> + /* WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl,bxt,kbl,cfl */ > > The hsds seem to be saying that this was fixed in kbl/cnl. I guess the > flicker could be due to a different vt-d vs. fbc issue. > I was trusting the wa database on this one. > Is the chicken bit in CHICKEN_PIPESL in the correct position? Yes it is zero. > > Hmm. Bspec doesn't list chicken bit for glk. That would seem to suggest > that we need this w/a for glk as well. Agreed. The questio is that should we follow bspec and logic or leave it until we get a report if it is a problem? cfl is close enough|similar in this respect that we mimic kbl with it? Thanks, -Mika > >> if (intel_vtd_active() && >> - (IS_SKYLAKE(dev_priv) || IS_BROXTON(dev_priv))) { >> + (IS_SKYLAKE(dev_priv) || IS_BROXTON(dev_priv) || >> + IS_KABYLAKE(dev_priv) || IS_COFFEELAKE(dev_priv))) { >> DRM_INFO("Disabling framebuffer compression (FBC) to prevent screen flicker with VT-d enabled\n"); >> return true; >> } >> -- >> 2.17.1 > > -- > Ville Syrjälä > Intel