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

[Lee, Shawn C]

On Tue, Sept. 15, 2020, 1:35 p.m. Ville Syrjälä wrote:
>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.

Customer already confirmed display flicker issue disappear after
applied this w/a.

BTW, here is the patch v2 to fix some typo in v1.
https://patchwork.freedesktop.org/series/81087/#rev2

Best regards,
Shawn

>
>> 
>> >
>> >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 at linux.intel.com>
>> >> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
>> >> Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
>> >> Cc: Jani Nikula <jani.nikula at intel.com>
>> >> Cc: William Tseng <william.tseng at intel.com>
>> >> Cc: Cooper Chiou <cooper.chiou at intel.com>
>> >> Signed-off-by: Lee Shawn C <shawn.c.lee at 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