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