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

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

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?

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
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