Re: [Intel-gfx] [PATCH] drm/i915/fbc: disable FBC on Nightfury board

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Tue, Sep 15, 2020 at 01:18:13PM +0000, Lee, Shawn C wrote:
> On Fri, Sept. 11, 2020, 2:21 p.m. Ville Syrjälä wrote:
> >On Thu, Aug 27, 2020 at 01:51:29PM +0800, Lee Shawn C wrote:
> >> Customer report random display flicker issue on Nightfury board.
> >> And we found this problem might be caused by VT-d and FBC are both 
> >> enabled. According to sighting report, it recommend to turn
> >> drm/i915/fbc: disable FBC on Nightfury board
> >> 
> >> Customer report random display flicker issue on Nightfury board.
> >> And we found this problem might be caused by VT-d and FBC are both 
> >> enabled. According to sighting report, it recommend to turn FBC off to 
> >> workaround this kind of issue.
> >> 
> >> This change refer to DMI BOARD_VENDOR and BOARD_NAME information to 
> >> disable FBC.
> >
> >What is this "nightfury board" exactly?
> 
> It is chrome os project on CML platform. The board name is "nightfury".

OK, then someone should definitely test if that missing w/a
fixes the underruns.

> 
> >
> >I think we're missing at least one fbc vs. vt-d w/a on some kbl/cfl/etc. era platforms:
> >git://github.com/vsyrjala/linux.git  vtd_wa_1142
> >
> >> 
> >> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> >> Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
> >> Cc: Jani Nikula <jani.nikula@intel.com>
> >> Cc: William Tseng <william.tseng@intel.com>
> >> Cc: Cooper Chiou <cooper.chiou@intel.com>
> >> Signed-off-by: Lee Shawn C <shawn.c.lee@intel.com>
> >> ---
> >>  drivers/gpu/drm/i915/display/intel_fbc.c | 22 ++++++++++++++++++++++
> >>  1 file changed, 22 insertions(+)
> >> 
> >> diff --git a/drivers/gpu/drm/i915/display/intel_fbc.c 
> >> b/drivers/gpu/drm/i915/display/intel_fbc.c
> >> index 327af428d73f..20660fdbab36 100644
> >> --- a/drivers/gpu/drm/i915/display/intel_fbc.c
> >> +++ b/drivers/gpu/drm/i915/display/intel_fbc.c
> >> @@ -39,6 +39,7 @@
> >>   */
> >>  
> >>  #include <drm/drm_fourcc.h>
> >> +#include <linux/dmi.h>
> >>  
> >>  #include "i915_drv.h"
> >>  #include "i915_trace.h"
> >> @@ -1439,6 +1440,24 @@ static int intel_sanitize_fbc_option(struct drm_i915_private *dev_priv)
> >>  	return 0;
> >>  }
> >>  
> >> +static int intel_fbc_vtd_callback(const struct dmi_system_id *id) {
> >> +	DRM_DEBUG_KMS("Disabling FBC to prevent screen flicker on %s device\n", id->ident);
> >> +	return 1;
> >> +}
> >> +
> >> +static const struct dmi_system_id intel_fbc_vtd_detect[] = {
> >> +	{
> >> +		.callback = intel_fbc_vtd_callback,
> >> +		.ident = "Google Nightfury",
> >> +		.matches = {
> >> +			DMI_MATCH(DMI_BOARD_VENDOR, "Google"),
> >> +			DMI_MATCH(DMI_BOARD_NAME, "Nightfury"),
> >> +		},
> >> +	},
> >> +	{ }
> >> +};
> >> +
> >>  static bool need_fbc_vtd_wa(struct drm_i915_private *dev_priv)  {
> >>  	/* WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl,bxt */ @@ -1450,6 +1469,9 
> >> @@ static bool need_fbc_vtd_wa(struct drm_i915_private *dev_priv)
> >>  		return true;
> >>  	}
> >>  
> >> +	if (dmi_check_system(intel_fbc_vtd_detect))
> >> +		return true;
> >> +
> >>  	return false;
> >>  }
> >>  
> >> --
> >> 2.17.1
> >
> >--
> >Ville Syrjälä
> >Intel
> 
> Best regards,
> Shawn

-- 
Ville Syrjälä
Intel
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