[PATCH v3] drm/i915/fbc: FBC causes display flicker when VT-d is enabled on Skylake

[PATCH v3] drm/i915/fbc: FBC causes display flicker when VT-d is enabled on Skylake

[Chris Wilson]

Erratum SKL075: Display Flicker May Occur When Both VT-d And FBC Are Enabled

"Display flickering may occur when both FBC (Frame Buffer Compression)
and VT - d (Intel® Virtualization Technology for Directed I/O) are enabled
and in use by the display controller."

Ville found the w/a name in the database:
WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl

v2: Log when the quirk is applied.
v3: Ensure i915.enable_fbc is false when !HAS_FBC()

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h  |  2 ++
 drivers/gpu/drm/i915/intel_fbc.c | 19 +++++++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 89298d3ad94b..f1e9fd07d441 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2586,6 +2586,8 @@ struct drm_i915_cmd_table {
 #define INTEL_GEN(p)	(INTEL_INFO(p)->gen)
 #define INTEL_DEVID(p)	(INTEL_INFO(p)->device_id)
 
+#define mkwrite_intel_info(p) ((struct intel_device_info *)INTEL_INFO(p))
+
 #define REVID_FOREVER		0xff
 #define INTEL_REVID(p)	(__I915__(p)->drm.pdev->revision)
 
diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
index ac26aa8be9d0..fd5865d80bec 100644
--- a/drivers/gpu/drm/i915/intel_fbc.c
+++ b/drivers/gpu/drm/i915/intel_fbc.c
@@ -1238,12 +1238,28 @@ static int intel_sanitize_fbc_option(struct drm_i915_private *dev_priv)
 	if (i915.enable_fbc >= 0)
 		return !!i915.enable_fbc;
 
+	if (!HAS_FBC(dev_priv))
+		return 0;
+
 	if (IS_BROADWELL(dev_priv))
 		return 1;
 
 	return 0;
 }
 
+static bool need_fbc_wa(struct drm_i915_private *dev_priv)
+{
+#ifdef CONFIG_INTEL_IOMMU
+	/* WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl */
+	if (intel_iommu_gfx_mapped && IS_SKYLAKE(dev_priv)) {
+		DRM_INFO("Disabling framebuffer compression (FBC) to prevent screen flicker with VT-d enabled\n");
+		return true;
+	}
+#endif
+
+	return false;
+}
+
 /**
  * intel_fbc_init - Initialize FBC
  * @dev_priv: the i915 device
@@ -1261,6 +1277,9 @@ void intel_fbc_init(struct drm_i915_private *dev_priv)
 	fbc->active = false;
 	fbc->work.scheduled = false;
 
+	if (need_fbc_wa(dev_priv))
+		mkwrite_intel_info(dev_priv)->has_fbc = false;
+
 	i915.enable_fbc = intel_sanitize_fbc_option(dev_priv);
 	DRM_DEBUG_KMS("Sanitized enable_fbc value: %d\n", i915.enable_fbc);
 
-- 
2.8.1

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Re: [PATCH v3] drm/i915/fbc: FBC causes display flicker when VT-d is enabled on Skylake

[Daniel Vetter]

On Tue, Jun 21, 2016 at 08:25:27AM +0100, Chris Wilson wrote:
> Erratum SKL075: Display Flicker May Occur When Both VT-d And FBC Are Enabled
> 
> "Display flickering may occur when both FBC (Frame Buffer Compression)
> and VT - d (Intel® Virtualization Technology for Directed I/O) are enabled
> and in use by the display controller."
> 
> Ville found the w/a name in the database:
> WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl
> 
> v2: Log when the quirk is applied.
> v3: Ensure i915.enable_fbc is false when !HAS_FBC()
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>

Do we know whether this helps on other machines too? I can imagine that
the additional lookup latency just plain wreaks havoc everywhere ...
-Daniel

> ---
>  drivers/gpu/drm/i915/i915_drv.h  |  2 ++
>  drivers/gpu/drm/i915/intel_fbc.c | 19 +++++++++++++++++++
>  2 files changed, 21 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 89298d3ad94b..f1e9fd07d441 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -2586,6 +2586,8 @@ struct drm_i915_cmd_table {
>  #define INTEL_GEN(p)	(INTEL_INFO(p)->gen)
>  #define INTEL_DEVID(p)	(INTEL_INFO(p)->device_id)
>  
> +#define mkwrite_intel_info(p) ((struct intel_device_info *)INTEL_INFO(p))
> +
>  #define REVID_FOREVER		0xff
>  #define INTEL_REVID(p)	(__I915__(p)->drm.pdev->revision)
>  
> diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
> index ac26aa8be9d0..fd5865d80bec 100644
> --- a/drivers/gpu/drm/i915/intel_fbc.c
> +++ b/drivers/gpu/drm/i915/intel_fbc.c
> @@ -1238,12 +1238,28 @@ static int intel_sanitize_fbc_option(struct drm_i915_private *dev_priv)
>  	if (i915.enable_fbc >= 0)
>  		return !!i915.enable_fbc;
>  
> +	if (!HAS_FBC(dev_priv))
> +		return 0;
> +
>  	if (IS_BROADWELL(dev_priv))
>  		return 1;
>  
>  	return 0;
>  }
>  
> +static bool need_fbc_wa(struct drm_i915_private *dev_priv)
> +{
> +#ifdef CONFIG_INTEL_IOMMU
> +	/* WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl */
> +	if (intel_iommu_gfx_mapped && IS_SKYLAKE(dev_priv)) {
> +		DRM_INFO("Disabling framebuffer compression (FBC) to prevent screen flicker with VT-d enabled\n");
> +		return true;
> +	}
> +#endif
> +
> +	return false;
> +}
> +
>  /**
>   * intel_fbc_init - Initialize FBC
>   * @dev_priv: the i915 device
> @@ -1261,6 +1277,9 @@ void intel_fbc_init(struct drm_i915_private *dev_priv)
>  	fbc->active = false;
>  	fbc->work.scheduled = false;
>  
> +	if (need_fbc_wa(dev_priv))
> +		mkwrite_intel_info(dev_priv)->has_fbc = false;
> +
>  	i915.enable_fbc = intel_sanitize_fbc_option(dev_priv);
>  	DRM_DEBUG_KMS("Sanitized enable_fbc value: %d\n", i915.enable_fbc);
>  
> -- 
> 2.8.1
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [PATCH v3] drm/i915/fbc: FBC causes display flicker when VT-d is enabled on Skylake

[Chris Wilson]

On Tue, Jun 21, 2016 at 03:31:25PM +0200, Daniel Vetter wrote:
> On Tue, Jun 21, 2016 at 08:25:27AM +0100, Chris Wilson wrote:
> > Erratum SKL075: Display Flicker May Occur When Both VT-d And FBC Are Enabled
> > 
> > "Display flickering may occur when both FBC (Frame Buffer Compression)
> > and VT - d (Intel® Virtualization Technology for Directed I/O) are enabled
> > and in use by the display controller."
> > 
> > Ville found the w/a name in the database:
> > WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl
> > 
> > v2: Log when the quirk is applied.
> > v3: Ensure i915.enable_fbc is false when !HAS_FBC()
> > 
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
> > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> Do we know whether this helps on other machines too? I can imagine that
> the additional lookup latency just plain wreaks havoc everywhere ...

Yeah, they do tend to play into fifo trouble. Could find anything
though. But I think we have enough evidence to suggest acking this w/a
and moving forward if we find any others...
-Chris

-- 
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Re: [PATCH v3] drm/i915/fbc: FBC causes display flicker when VT-d is enabled on Skylake

[Zanoni, Paulo R]

Em Ter, 2016-06-21 às 08:25 +0100, Chris Wilson escreveu:
> Erratum SKL075: Display Flicker May Occur When Both VT-d And FBC Are
> Enabled
> 
> "Display flickering may occur when both FBC (Frame Buffer
> Compression)
> and VT - d (Intel® Virtualization Technology for Directed I/O) are
> enabled
> and in use by the display controller."
> 
> Ville found the w/a name in the database:
> WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl
> 
> v2: Log when the quirk is applied.
> v3: Ensure i915.enable_fbc is false when !HAS_FBC()
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.h  |  2 ++
>  drivers/gpu/drm/i915/intel_fbc.c | 19 +++++++++++++++++++
>  2 files changed, 21 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h
> b/drivers/gpu/drm/i915/i915_drv.h
> index 89298d3ad94b..f1e9fd07d441 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -2586,6 +2586,8 @@ struct drm_i915_cmd_table {
>  #define INTEL_GEN(p)	(INTEL_INFO(p)->gen)
>  #define INTEL_DEVID(p)	(INTEL_INFO(p)->device_id)
>  
> +#define mkwrite_intel_info(p) ((struct intel_device_info
> *)INTEL_INFO(p))

So why don't we un-const struct intel_device_info?

> +
>  #define REVID_FOREVER		0xff
>  #define INTEL_REVID(p)	(__I915__(p)->drm.pdev->revision)
>  
> diff --git a/drivers/gpu/drm/i915/intel_fbc.c
> b/drivers/gpu/drm/i915/intel_fbc.c
> index ac26aa8be9d0..fd5865d80bec 100644
> --- a/drivers/gpu/drm/i915/intel_fbc.c
> +++ b/drivers/gpu/drm/i915/intel_fbc.c
> @@ -1238,12 +1238,28 @@ static int intel_sanitize_fbc_option(struct
> drm_i915_private *dev_priv)
>  	if (i915.enable_fbc >= 0)
>  		return !!i915.enable_fbc;
>  
> +	if (!HAS_FBC(dev_priv))
> +		return 0;
> +
>  	if (IS_BROADWELL(dev_priv))
>  		return 1;
>  
>  	return 0;
>  }
>  
> +static bool need_fbc_wa(struct drm_i915_private *dev_priv)
> +{
> +#ifdef CONFIG_INTEL_IOMMU
> +	/* WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl */
> +	if (intel_iommu_gfx_mapped 

The doc says: "Workaround: Disable FBC when VT-d superpage is used.".
My iommu-fu is not strong enough for me to be 100% sure that the
variable above corresponds to that. I'll just have to take your word
here.


> && IS_SKYLAKE(dev_priv)) {

The WA also applies to BXT, and pre-prod KBL, so I suppose at least a
check for BXT would be good.

> +		DRM_INFO("Disabling framebuffer compression (FBC) to
> prevent screen flicker with VT-d enabled\n");
> +		return true;
> +	}
> +#endif
> +
> +	return false;
> +}
> +
>  /**
>   * intel_fbc_init - Initialize FBC
>   * @dev_priv: the i915 device
> @@ -1261,6 +1277,9 @@ void intel_fbc_init(struct drm_i915_private
> *dev_priv)
>  	fbc->active = false;
>  	fbc->work.scheduled = false;
>  
> +	if (need_fbc_wa(dev_priv))
> +		mkwrite_intel_info(dev_priv)->has_fbc = false;
> +
>  	i915.enable_fbc = intel_sanitize_fbc_option(dev_priv);
>  	DRM_DEBUG_KMS("Sanitized enable_fbc value: %d\n",
> i915.enable_fbc);
>  
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Re: [PATCH v3] drm/i915/fbc: FBC causes display flicker when VT-d is enabled on Skylake

[Zanoni, Paulo R]

Em Qua, 2016-06-22 às 21:34 +0100, Chris Wilson escreveu:
> On Tue, Jun 21, 2016 at 03:31:25PM +0200, Daniel Vetter wrote:
> > 
> > On Tue, Jun 21, 2016 at 08:25:27AM +0100, Chris Wilson wrote:
> > > 
> > > Erratum SKL075: Display Flicker May Occur When Both VT-d And FBC
> > > Are Enabled
> > > 
> > > "Display flickering may occur when both FBC (Frame Buffer
> > > Compression)
> > > and VT - d (Intel® Virtualization Technology for Directed I/O)
> > > are enabled
> > > and in use by the display controller."
> > > 
> > > Ville found the w/a name in the database:
> > > WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl
> > > 
> > > v2: Log when the quirk is applied.
> > > v3: Ensure i915.enable_fbc is false when !HAS_FBC()
> > > 
> > > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > > Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
> > > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > Do we know whether this helps on other machines too? I can imagine
> > that
> > the additional lookup latency just plain wreaks havoc everywhere
> > ...
> Yeah, they do tend to play into fifo trouble. Could find anything
> though. But I think we have enough evidence to suggest acking this
> w/a
> and moving forward if we find any others...

From the HSD, it looks like this problem would lead to an underrun, so
the "disable FBC if we ever get an underrun" would at least help
diminish the damage in case the WA is actually valid for the previous
gens.

> -Chris
> 
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Re: [PATCH v3] drm/i915/fbc: FBC causes display flicker when VT-d is enabled on Skylake

[Jani Nikula]

On Thu, 23 Jun 2016, "Zanoni, Paulo R" <paulo.r.zanoni@intel.com> wrote:
> Em Ter, 2016-06-21 às 08:25 +0100, Chris Wilson escreveu:
>> Erratum SKL075: Display Flicker May Occur When Both VT-d And FBC Are
>> Enabled
>> 
>> "Display flickering may occur when both FBC (Frame Buffer
>> Compression)
>> and VT - d (Intel® Virtualization Technology for Directed I/O) are
>> enabled
>> and in use by the display controller."
>> 
>> Ville found the w/a name in the database:
>> WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl
>> 
>> v2: Log when the quirk is applied.
>> v3: Ensure i915.enable_fbc is false when !HAS_FBC()
>> 
>> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
>> Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
>> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
>> ---
>>  drivers/gpu/drm/i915/i915_drv.h  |  2 ++
>>  drivers/gpu/drm/i915/intel_fbc.c | 19 +++++++++++++++++++
>>  2 files changed, 21 insertions(+)
>> 
>> diff --git a/drivers/gpu/drm/i915/i915_drv.h
>> b/drivers/gpu/drm/i915/i915_drv.h
>> index 89298d3ad94b..f1e9fd07d441 100644
>> --- a/drivers/gpu/drm/i915/i915_drv.h
>> +++ b/drivers/gpu/drm/i915/i915_drv.h
>> @@ -2586,6 +2586,8 @@ struct drm_i915_cmd_table {
>>  #define INTEL_GEN(p)	(INTEL_INFO(p)->gen)
>>  #define INTEL_DEVID(p)	(INTEL_INFO(p)->device_id)
>>  
>> +#define mkwrite_intel_info(p) ((struct intel_device_info
>> *)INTEL_INFO(p))
>
> So why don't we un-const struct intel_device_info?

Yeah, this is more than a little ugly. Either it should stay const and
we shouldn't modify it (except in intel_device_info_runtime_init(), and
even that is a bit ugly), or we make it non-const.

BR,
Jani.

-- 
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[PATCH] drm/i915/fbc: FBC causes display flicker when VT-d is enabled on Skylake

[Chris Wilson]

Erratum SKL075: Display Flicker May Occur When Both VT-d And FBC Are Enabled

"Display flickering may occur when both FBC (Frame Buffer Compression)
and VT - d (Intel® Virtualization Technology for Directed I/O) are enabled
and in use by the display controller."

Ville found the w/a name in the database:
WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl

v2: Log when the quirk is applied.
v3: Ensure i915.enable_fbc is false when !HAS_FBC()

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
---

Paulo, I was under the impression you wanted to ack this as a known
issue?
-Chris

---
 drivers/gpu/drm/i915/intel_fbc.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
index 06d3a86828fc..17343baf25ea 100644
--- a/drivers/gpu/drm/i915/intel_fbc.c
+++ b/drivers/gpu/drm/i915/intel_fbc.c
@@ -1240,12 +1240,28 @@ static int intel_sanitize_fbc_option(struct drm_i915_private *dev_priv)
 	if (i915.enable_fbc >= 0)
 		return !!i915.enable_fbc;
 
+	if (!HAS_FBC(dev_priv))
+		return 0;
+
 	if (IS_BROADWELL(dev_priv))
 		return 1;
 
 	return 0;
 }
 
+static bool need_fbc_wa(struct drm_i915_private *dev_priv)
+{
+#ifdef CONFIG_INTEL_IOMMU
+	/* WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl */
+	if (intel_iommu_gfx_mapped && IS_SKYLAKE(dev_priv)) {
+		DRM_INFO("Disabling framebuffer compression (FBC) to prevent screen flicker with VT-d enabled\n");
+		return true;
+	}
+#endif
+
+	return false;
+}
+
 /**
  * intel_fbc_init - Initialize FBC
  * @dev_priv: the i915 device
@@ -1263,6 +1279,9 @@ void intel_fbc_init(struct drm_i915_private *dev_priv)
 	fbc->active = false;
 	fbc->work.scheduled = false;
 
+	if (need_fbc_wa(dev_priv))
+		mkwrite_intel_info(dev_priv)->has_fbc = false;
+
 	i915.enable_fbc = intel_sanitize_fbc_option(dev_priv);
 	DRM_DEBUG_KMS("Sanitized enable_fbc value: %d\n", i915.enable_fbc);
 
-- 
2.8.1

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✗ Ro.CI.BAT: failure for drm/i915/fbc: FBC causes display flicker when VT-d is enabled on Skylake

[Patchwork]

== Series Details ==

Series: drm/i915/fbc: FBC causes display flicker when VT-d is enabled on Skylake
URL   : https://patchwork.freedesktop.org/series/10606/
State : failure

== Summary ==

  CC      drivers/pci/pci-acpi.o
  CC      drivers/pci/pcie/aer/aerdrv_core.o
  CC [M]  drivers/net/ethernet/intel/igb/e1000_nvm.o
  CC [M]  drivers/net/ethernet/intel/igbvf/netdev.o
  CC      drivers/pci/pcie/aer/aerdrv.o
  CC      drivers/pci/pcie/aer/aerdrv_acpi.o
  CC      drivers/pci/pcie/aer/ecrc.o
  CC [M]  drivers/net/ethernet/intel/igb/e1000_phy.o
  CC      drivers/pci/pci-label.o
  CC [M]  drivers/net/ethernet/intel/igb/e1000_mbx.o
  CC [M]  drivers/net/ethernet/intel/e1000e/param.o
  CC [M]  drivers/net/ethernet/intel/igb/e1000_i210.o
  LD [M]  drivers/net/ethernet/intel/e1000/e1000.o
  CC [M]  drivers/net/ethernet/intel/igb/igb_ptp.o
  CC [M]  drivers/net/ethernet/intel/igb/igb_hwmon.o
  CC [M]  drivers/net/ethernet/intel/e1000e/ethtool.o
  CC [M]  drivers/net/ethernet/intel/e1000e/netdev.o
  CC [M]  drivers/net/ethernet/intel/e1000e/ptp.o
  LD      drivers/pci/pcie/pcieportdrv.o
  LD      drivers/pci/pcie/aer/aerdriver.o
  LD      drivers/pci/pcie/aer/built-in.o
  LD      drivers/pci/pcie/built-in.o
  LD      drivers/pci/built-in.o
  LD [M]  drivers/net/ethernet/intel/igbvf/igbvf.o
  LD [M]  drivers/net/ethernet/intel/igb/igb.o
  LD [M]  drivers/net/ethernet/intel/e1000e/e1000e.o
  LD      drivers/net/ethernet/built-in.o
  LD      drivers/net/built-in.o
Makefile:976: recipe for target 'drivers' failed
make: *** [drivers] Error 2

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[PATCH v2] drm/i915/fbc: FBC causes display flicker when VT-d is enabled on Skylake

[Chris Wilson]

Erratum SKL075: Display Flicker May Occur When Both VT-d And FBC Are Enabled

"Display flickering may occur when both FBC (Frame Buffer Compression)
and VT - d (Intel® Virtualization Technology for Directed I/O) are enabled
and in use by the display controller."

Ville found the w/a name in the database:
WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl

v2: Log when the quirk is applied.
v3: Ensure i915.enable_fbc is false when !HAS_FBC()
v4: Fix function name after rebase

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/i915/intel_fbc.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
index 8147eb9e8475..b673c7c54a46 100644
--- a/drivers/gpu/drm/i915/intel_fbc.c
+++ b/drivers/gpu/drm/i915/intel_fbc.c
@@ -1229,12 +1229,28 @@ static int intel_sanitize_fbc_option(struct drm_i915_private *dev_priv)
 	if (i915.enable_fbc >= 0)
 		return !!i915.enable_fbc;
 
+	if (!HAS_FBC(dev_priv))
+		return 0;
+
 	if (IS_BROADWELL(dev_priv))
 		return 1;
 
 	return 0;
 }
 
+static bool need_fbc_wa(struct drm_i915_private *dev_priv)
+{
+#ifdef CONFIG_INTEL_IOMMU
+	/* WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl */
+	if (intel_iommu_gfx_mapped && IS_SKYLAKE(dev_priv)) {
+		DRM_INFO("Disabling framebuffer compression (FBC) to prevent screen flicker with VT-d enabled\n");
+		return true;
+	}
+#endif
+
+	return false;
+}
+
 /**
  * intel_fbc_init - Initialize FBC
  * @dev_priv: the i915 device
@@ -1252,6 +1268,9 @@ void intel_fbc_init(struct drm_i915_private *dev_priv)
 	fbc->active = false;
 	fbc->work.scheduled = false;
 
+	if (need_fbc_wa(dev_priv))
+		mkwrite_device_info(dev_priv)->has_fbc = false;
+
 	i915.enable_fbc = intel_sanitize_fbc_option(dev_priv);
 	DRM_DEBUG_KMS("Sanitized enable_fbc value: %d\n", i915.enable_fbc);
 
-- 
2.8.1

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Re: [PATCH] drm/i915/fbc: FBC causes display flicker when VT-d is enabled on Skylake

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 1803 bytes --]

Hi Chris,

[auto build test ERROR on drm-intel/for-linux-next]
[also build test ERROR on next-20160803]
[cannot apply to v4.7]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Chris-Wilson/drm-i915-fbc-FBC-causes-display-flicker-when-VT-d-is-enabled-on-Skylake/20160804-001041
base:   git://anongit.freedesktop.org/drm-intel for-linux-next
config: x86_64-randconfig-x015-201631 (attached as .config)
compiler: gcc-6 (Debian 6.1.1-9) 6.1.1 20160705
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All errors (new ones prefixed by >>):

   drivers/gpu/drm/i915/intel_fbc.c: In function 'intel_fbc_init':
>> drivers/gpu/drm/i915/intel_fbc.c:1273:3: error: implicit declaration of function 'mkwrite_intel_info' [-Werror=implicit-function-declaration]
      mkwrite_intel_info(dev_priv)->has_fbc = false;
      ^~~~~~~~~~~~~~~~~~
>> drivers/gpu/drm/i915/intel_fbc.c:1273:31: error: invalid type argument of '->' (have 'int')
      mkwrite_intel_info(dev_priv)->has_fbc = false;
                                  ^~
   cc1: some warnings being treated as errors

vim +/mkwrite_intel_info +1273 drivers/gpu/drm/i915/intel_fbc.c

  1267		mutex_init(&fbc->lock);
  1268		fbc->enabled = false;
  1269		fbc->active = false;
  1270		fbc->work.scheduled = false;
  1271	
  1272		if (need_fbc_wa(dev_priv))
> 1273			mkwrite_intel_info(dev_priv)->has_fbc = false;
  1274	
  1275		i915.enable_fbc = intel_sanitize_fbc_option(dev_priv);
  1276		DRM_DEBUG_KMS("Sanitized enable_fbc value: %d\n", i915.enable_fbc);

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

[-- Attachment #2: .config.gz --]
[-- Type: application/octet-stream, Size: 27321 bytes --]

[-- Attachment #3: Type: text/plain, Size: 160 bytes --]

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✗ Ro.CI.BAT: warning for drm/i915/fbc: FBC causes display flicker when VT-d is enabled on Skylake (rev2)

[Patchwork]

== Series Details ==

Series: drm/i915/fbc: FBC causes display flicker when VT-d is enabled on Skylake (rev2)
URL   : https://patchwork.freedesktop.org/series/10606/
State : warning

== Summary ==

Series 10606v2 drm/i915/fbc: FBC causes display flicker when VT-d is enabled on Skylake
http://patchwork.freedesktop.org/api/1.0/series/10606/revisions/2/mbox

Test drv_module_reload_basic:
                pass       -> SKIP       (ro-hsw-i3-4010u)
                pass       -> SKIP       (fi-skl-i5-6260u)
Test gem_exec_gttfill:
        Subgroup basic:
                skip       -> PASS       (fi-snb-i7-2600)
Test kms_cursor_legacy:
        Subgroup basic-flip-vs-cursor-legacy:
                fail       -> PASS       (ro-hsw-i7-4770r)
        Subgroup basic-flip-vs-cursor-varying-size:
                fail       -> PASS       (ro-skl3-i5-6260u)

fi-hsw-i7-4770k  total:240  pass:218  dwarn:0   dfail:0   fail:0   skip:22 
fi-kbl-qkkr      total:240  pass:182  dwarn:28  dfail:0   fail:3   skip:27 
fi-skl-i5-6260u  total:240  pass:223  dwarn:0   dfail:0   fail:2   skip:15 
fi-skl-i7-6700k  total:240  pass:209  dwarn:0   dfail:0   fail:3   skip:28 
fi-snb-i7-2600   total:240  pass:198  dwarn:0   dfail:0   fail:0   skip:42 
ro-bdw-i5-5250u  total:240  pass:220  dwarn:4   dfail:0   fail:0   skip:16 
ro-bdw-i7-5557U  total:240  pass:224  dwarn:0   dfail:0   fail:0   skip:16 
ro-bdw-i7-5600u  total:240  pass:206  dwarn:0   dfail:0   fail:2   skip:32 
ro-bsw-n3050     total:240  pass:195  dwarn:0   dfail:0   fail:3   skip:42 
ro-byt-n2820     total:240  pass:197  dwarn:0   dfail:0   fail:3   skip:40 
ro-hsw-i3-4010u  total:240  pass:213  dwarn:0   dfail:0   fail:0   skip:27 
ro-hsw-i7-4770r  total:240  pass:214  dwarn:0   dfail:0   fail:0   skip:26 
ro-ilk-i7-620lm  total:240  pass:173  dwarn:1   dfail:0   fail:1   skip:65 
ro-ilk1-i5-650   total:235  pass:173  dwarn:0   dfail:0   fail:2   skip:60 
ro-ivb2-i7-3770  total:240  pass:209  dwarn:0   dfail:0   fail:0   skip:31 
ro-skl3-i5-6260u total:240  pass:223  dwarn:0   dfail:0   fail:3   skip:14 
ro-ivb-i7-3770 failed to connect after reboot
ro-snb-i7-2620M failed to connect after reboot

Results at /archive/results/CI_IGT_test/RO_Patchwork_1686/

4d6f224 drm-intel-nightly: 2016y-08m-03d-15h-38m-31s UTC integration manifest
cb4539a drm/i915/fbc: FBC causes display flicker when VT-d is enabled on Skylake

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Re: [PATCH v2] drm/i915/fbc: FBC causes display flicker when VT-d is enabled on Skylake

[Jani Nikula]

On Wed, 03 Aug 2016, Chris Wilson <chris@chris-wilson.co.uk> wrote:
> Erratum SKL075: Display Flicker May Occur When Both VT-d And FBC Are Enabled
>
> "Display flickering may occur when both FBC (Frame Buffer Compression)
> and VT - d (Intel® Virtualization Technology for Directed I/O) are enabled
> and in use by the display controller."
>
> Ville found the w/a name in the database:
> WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl
>
> v2: Log when the quirk is applied.
> v3: Ensure i915.enable_fbc is false when !HAS_FBC()
> v4: Fix function name after rebase
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>

Cc: stable@vger.kernel.org

?

> ---
>  drivers/gpu/drm/i915/intel_fbc.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
> index 8147eb9e8475..b673c7c54a46 100644
> --- a/drivers/gpu/drm/i915/intel_fbc.c
> +++ b/drivers/gpu/drm/i915/intel_fbc.c
> @@ -1229,12 +1229,28 @@ static int intel_sanitize_fbc_option(struct drm_i915_private *dev_priv)
>  	if (i915.enable_fbc >= 0)
>  		return !!i915.enable_fbc;
>  
> +	if (!HAS_FBC(dev_priv))
> +		return 0;
> +
>  	if (IS_BROADWELL(dev_priv))
>  		return 1;
>  
>  	return 0;
>  }
>  
> +static bool need_fbc_wa(struct drm_i915_private *dev_priv)
> +{
> +#ifdef CONFIG_INTEL_IOMMU
> +	/* WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl */
> +	if (intel_iommu_gfx_mapped && IS_SKYLAKE(dev_priv)) {
> +		DRM_INFO("Disabling framebuffer compression (FBC) to prevent screen flicker with VT-d enabled\n");
> +		return true;
> +	}
> +#endif
> +
> +	return false;
> +}
> +
>  /**
>   * intel_fbc_init - Initialize FBC
>   * @dev_priv: the i915 device
> @@ -1252,6 +1268,9 @@ void intel_fbc_init(struct drm_i915_private *dev_priv)
>  	fbc->active = false;
>  	fbc->work.scheduled = false;
>  
> +	if (need_fbc_wa(dev_priv))
> +		mkwrite_device_info(dev_priv)->has_fbc = false;
> +
>  	i915.enable_fbc = intel_sanitize_fbc_option(dev_priv);
>  	DRM_DEBUG_KMS("Sanitized enable_fbc value: %d\n", i915.enable_fbc);

-- 
Jani Nikula, Intel Open Source Technology Center
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Re: [PATCH v2] drm/i915/fbc: FBC causes display flicker when VT-d is enabled on Skylake

[Ville Syrjälä]

On Wed, Aug 03, 2016 at 05:16:42PM +0100, Chris Wilson wrote:
> Erratum SKL075: Display Flicker May Occur When Both VT-d And FBC Are Enabled
> 
> "Display flickering may occur when both FBC (Frame Buffer Compression)
> and VT - d (Intel® Virtualization Technology for Directed I/O) are enabled
> and in use by the display controller."
> 
> Ville found the w/a name in the database:
> WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl
> 
> v2: Log when the quirk is applied.
> v3: Ensure i915.enable_fbc is false when !HAS_FBC()
> v4: Fix function name after rebase
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_fbc.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
> index 8147eb9e8475..b673c7c54a46 100644
> --- a/drivers/gpu/drm/i915/intel_fbc.c
> +++ b/drivers/gpu/drm/i915/intel_fbc.c
> @@ -1229,12 +1229,28 @@ static int intel_sanitize_fbc_option(struct drm_i915_private *dev_priv)
>  	if (i915.enable_fbc >= 0)
>  		return !!i915.enable_fbc;
>  
> +	if (!HAS_FBC(dev_priv))
> +		return 0;
> +
>  	if (IS_BROADWELL(dev_priv))
>  		return 1;
>  
>  	return 0;
>  }
>  
> +static bool need_fbc_wa(struct drm_i915_private *dev_priv)

need_fbc_vtd_wa() perhaps?

> +{
> +#ifdef CONFIG_INTEL_IOMMU
> +	/* WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl */
> +	if (intel_iommu_gfx_mapped && IS_SKYLAKE(dev_priv)) {

BXT needs this as well AFAICS.

with that added
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> +		DRM_INFO("Disabling framebuffer compression (FBC) to prevent screen flicker with VT-d enabled\n");
> +		return true;
> +	}
> +#endif
> +
> +	return false;
> +}
> +
>  /**
>   * intel_fbc_init - Initialize FBC
>   * @dev_priv: the i915 device
> @@ -1252,6 +1268,9 @@ void intel_fbc_init(struct drm_i915_private *dev_priv)
>  	fbc->active = false;
>  	fbc->work.scheduled = false;
>  
> +	if (need_fbc_wa(dev_priv))
> +		mkwrite_device_info(dev_priv)->has_fbc = false;
> +
>  	i915.enable_fbc = intel_sanitize_fbc_option(dev_priv);
>  	DRM_DEBUG_KMS("Sanitized enable_fbc value: %d\n", i915.enable_fbc);
>  
> -- 
> 2.8.1

-- 
Ville Syrjälä
Intel OTC
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Re: [PATCH v2] drm/i915/fbc: FBC causes display flicker when VT-d is enabled on Skylake

[Chris Wilson]

On Thu, Aug 04, 2016 at 09:57:11AM +0300, Ville Syrjälä wrote:
> On Wed, Aug 03, 2016 at 05:16:42PM +0100, Chris Wilson wrote:
> > Erratum SKL075: Display Flicker May Occur When Both VT-d And FBC Are Enabled
> > 
> > "Display flickering may occur when both FBC (Frame Buffer Compression)
> > and VT - d (Intel® Virtualization Technology for Directed I/O) are enabled
> > and in use by the display controller."
> > 
> > Ville found the w/a name in the database:
> > WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl
> > 
> > v2: Log when the quirk is applied.
> > v3: Ensure i915.enable_fbc is false when !HAS_FBC()
> > v4: Fix function name after rebase
> > 
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
> > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_fbc.c | 19 +++++++++++++++++++
> >  1 file changed, 19 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
> > index 8147eb9e8475..b673c7c54a46 100644
> > --- a/drivers/gpu/drm/i915/intel_fbc.c
> > +++ b/drivers/gpu/drm/i915/intel_fbc.c
> > @@ -1229,12 +1229,28 @@ static int intel_sanitize_fbc_option(struct drm_i915_private *dev_priv)
> >  	if (i915.enable_fbc >= 0)
> >  		return !!i915.enable_fbc;
> >  
> > +	if (!HAS_FBC(dev_priv))
> > +		return 0;
> > +
> >  	if (IS_BROADWELL(dev_priv))
> >  		return 1;
> >  
> >  	return 0;
> >  }
> >  
> > +static bool need_fbc_wa(struct drm_i915_private *dev_priv)
> 
> need_fbc_vtd_wa() perhaps?

Right now, yes. I left it open just in case - but that's most likely a
false hope.

> > +{
> > +#ifdef CONFIG_INTEL_IOMMU
> > +	/* WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl */
> > +	if (intel_iommu_gfx_mapped && IS_SKYLAKE(dev_priv)) {
> 
> BXT needs this as well AFAICS.

Will IS_GEN9() suit? +skl,bxt in the description.
-Chris

-- 
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Re: [PATCH v2] drm/i915/fbc: FBC causes display flicker when VT-d is enabled on Skylake

[Ville Syrjälä]

On Thu, Aug 04, 2016 at 08:03:09AM +0100, Chris Wilson wrote:
> On Thu, Aug 04, 2016 at 09:57:11AM +0300, Ville Syrjälä wrote:
> > On Wed, Aug 03, 2016 at 05:16:42PM +0100, Chris Wilson wrote:
> > > Erratum SKL075: Display Flicker May Occur When Both VT-d And FBC Are Enabled
> > > 
> > > "Display flickering may occur when both FBC (Frame Buffer Compression)
> > > and VT - d (Intel® Virtualization Technology for Directed I/O) are enabled
> > > and in use by the display controller."
> > > 
> > > Ville found the w/a name in the database:
> > > WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl
> > > 
> > > v2: Log when the quirk is applied.
> > > v3: Ensure i915.enable_fbc is false when !HAS_FBC()
> > > v4: Fix function name after rebase
> > > 
> > > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > > Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
> > > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/intel_fbc.c | 19 +++++++++++++++++++
> > >  1 file changed, 19 insertions(+)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
> > > index 8147eb9e8475..b673c7c54a46 100644
> > > --- a/drivers/gpu/drm/i915/intel_fbc.c
> > > +++ b/drivers/gpu/drm/i915/intel_fbc.c
> > > @@ -1229,12 +1229,28 @@ static int intel_sanitize_fbc_option(struct drm_i915_private *dev_priv)
> > >  	if (i915.enable_fbc >= 0)
> > >  		return !!i915.enable_fbc;
> > >  
> > > +	if (!HAS_FBC(dev_priv))
> > > +		return 0;
> > > +
> > >  	if (IS_BROADWELL(dev_priv))
> > >  		return 1;
> > >  
> > >  	return 0;
> > >  }
> > >  
> > > +static bool need_fbc_wa(struct drm_i915_private *dev_priv)
> > 
> > need_fbc_vtd_wa() perhaps?
> 
> Right now, yes. I left it open just in case - but that's most likely a
> false hope.
> 
> > > +{
> > > +#ifdef CONFIG_INTEL_IOMMU
> > > +	/* WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl */
> > > +	if (intel_iommu_gfx_mapped && IS_SKYLAKE(dev_priv)) {
> > 
> > BXT needs this as well AFAICS.
> 
> Will IS_GEN9() suit? +skl,bxt in the description.

Looks like KBL doesn't need this w/a.

-- 
Ville Syrjälä
Intel OTC
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[PATCH v3] drm/i915/fbc: FBC causes display flicker when VT-d is enabled on Skylake

[Chris Wilson]

Erratum SKL075: Display Flicker May Occur When Both VT-d And FBC Are Enabled

"Display flickering may occur when both FBC (Frame Buffer Compression)
and VT - d (Intel® Virtualization Technology for Directed I/O) are enabled
and in use by the display controller."

Ville found the w/a name in the database:
WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl,bxt and also dug out that it
affects Broxton.

v2: Log when the quirk is applied.
v3: Ensure i915.enable_fbc is false when !HAS_FBC()
v4: Fix function name after rebase
v5: Add Broxton to the workaround

Note for backporting to stable, we need to add
	((struct intel_device_info *)INTEL_INFO(ptr))

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: stable@vger.kernel.org
---
 drivers/gpu/drm/i915/intel_fbc.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
index 8147eb9e8475..d4be07615aa9 100644
--- a/drivers/gpu/drm/i915/intel_fbc.c
+++ b/drivers/gpu/drm/i915/intel_fbc.c
@@ -1229,12 +1229,29 @@ static int intel_sanitize_fbc_option(struct drm_i915_private *dev_priv)
 	if (i915.enable_fbc >= 0)
 		return !!i915.enable_fbc;
 
+	if (!HAS_FBC(dev_priv))
+		return 0;
+
 	if (IS_BROADWELL(dev_priv))
 		return 1;
 
 	return 0;
 }
 
+static bool need_fbc_vtd_wa(struct drm_i915_private *dev_priv)
+{
+#ifdef CONFIG_INTEL_IOMMU
+	/* WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl,bxt */
+	if (intel_iommu_gfx_mapped &&
+	    (IS_SKYLAKE(dev_priv) || IS_BROXTON(dev_priv))) {
+		DRM_INFO("Disabling framebuffer compression (FBC) to prevent screen flicker with VT-d enabled\n");
+		return true;
+	}
+#endif
+
+	return false;
+}
+
 /**
  * intel_fbc_init - Initialize FBC
  * @dev_priv: the i915 device
@@ -1252,6 +1269,9 @@ void intel_fbc_init(struct drm_i915_private *dev_priv)
 	fbc->active = false;
 	fbc->work.scheduled = false;
 
+	if (need_fbc_vtd_wa(dev_priv))
+		mkwrite_device_info(dev_priv)->has_fbc = false;
+
 	i915.enable_fbc = intel_sanitize_fbc_option(dev_priv);
 	DRM_DEBUG_KMS("Sanitized enable_fbc value: %d\n", i915.enable_fbc);
 
-- 
2.8.1

✗ Ro.CI.BAT: failure for drm/i915/fbc: FBC causes display flicker when VT-d is enabled on Skylake (rev3)

[Patchwork]

== Series Details ==

Series: drm/i915/fbc: FBC causes display flicker when VT-d is enabled on Skylake (rev3)
URL   : https://patchwork.freedesktop.org/series/10606/
State : failure

== Summary ==

Series 10606v3 drm/i915/fbc: FBC causes display flicker when VT-d is enabled on Skylake
http://patchwork.freedesktop.org/api/1.0/series/10606/revisions/3/mbox

Test kms_cursor_legacy:
        Subgroup basic-flip-vs-cursor-legacy:
                fail       -> PASS       (ro-bdw-i7-5600u)
                fail       -> PASS       (ro-bdw-i5-5250u)
                pass       -> FAIL       (ro-skl3-i5-6260u)

fi-hsw-i7-4770k  total:240  pass:218  dwarn:0   dfail:0   fail:0   skip:22 
fi-kbl-qkkr      total:240  pass:182  dwarn:29  dfail:0   fail:3   skip:26 
fi-skl-i5-6260u  total:240  pass:224  dwarn:0   dfail:0   fail:2   skip:14 
fi-skl-i7-6700k  total:240  pass:208  dwarn:0   dfail:0   fail:4   skip:28 
fi-snb-i7-2600   total:240  pass:198  dwarn:0   dfail:0   fail:0   skip:42 
ro-bdw-i5-5250u  total:240  pass:219  dwarn:4   dfail:0   fail:1   skip:16 
ro-bdw-i7-5557U  total:240  pass:224  dwarn:0   dfail:0   fail:0   skip:16 
ro-bdw-i7-5600u  total:240  pass:207  dwarn:0   dfail:0   fail:1   skip:32 
ro-bsw-n3050     total:240  pass:194  dwarn:0   dfail:0   fail:4   skip:42 
ro-byt-n2820     total:240  pass:197  dwarn:0   dfail:0   fail:3   skip:40 
ro-hsw-i3-4010u  total:240  pass:214  dwarn:0   dfail:0   fail:0   skip:26 
ro-hsw-i7-4770r  total:240  pass:214  dwarn:0   dfail:0   fail:0   skip:26 
ro-ilk-i7-620lm  total:240  pass:173  dwarn:1   dfail:0   fail:1   skip:65 
ro-ilk1-i5-650   total:235  pass:173  dwarn:0   dfail:0   fail:2   skip:60 
ro-ivb-i7-3770   total:240  pass:205  dwarn:0   dfail:0   fail:0   skip:35 
ro-ivb2-i7-3770  total:240  pass:209  dwarn:0   dfail:0   fail:0   skip:31 
ro-skl3-i5-6260u total:240  pass:222  dwarn:0   dfail:0   fail:4   skip:14 
ro-snb-i7-2620M  total:240  pass:198  dwarn:0   dfail:0   fail:1   skip:41 

Results at /archive/results/CI_IGT_test/RO_Patchwork_1700/

4a66cc6 drm-intel-nightly: 2016y-08m-04d-08h-20m-44s UTC integration manifest
a02d00e drm/i915/fbc: FBC causes display flicker when VT-d is enabled on Skylake

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Re: [PATCH v2] drm/i915/fbc: FBC causes display flicker when VT-d is enabled on Skylake

[Daniel Vetter]

On Thu, Aug 04, 2016 at 09:31:20AM +0300, Jani Nikula wrote:
> On Wed, 03 Aug 2016, Chris Wilson <chris@chris-wilson.co.uk> wrote:
> > Erratum SKL075: Display Flicker May Occur When Both VT-d And FBC Are Enabled
> >
> > "Display flickering may occur when both FBC (Frame Buffer Compression)
> > and VT - d (Intel® Virtualization Technology for Directed I/O) are enabled
> > and in use by the display controller."
> >
> > Ville found the w/a name in the database:
> > WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl
> >
> > v2: Log when the quirk is applied.
> > v3: Ensure i915.enable_fbc is false when !HAS_FBC()
> > v4: Fix function name after rebase
> >
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
> > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> Cc: stable@vger.kernel.org

fbc isn't enabled by default, so imo no.
-Daniel

> 
> ?
> 
> > ---
> >  drivers/gpu/drm/i915/intel_fbc.c | 19 +++++++++++++++++++
> >  1 file changed, 19 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
> > index 8147eb9e8475..b673c7c54a46 100644
> > --- a/drivers/gpu/drm/i915/intel_fbc.c
> > +++ b/drivers/gpu/drm/i915/intel_fbc.c
> > @@ -1229,12 +1229,28 @@ static int intel_sanitize_fbc_option(struct drm_i915_private *dev_priv)
> >  	if (i915.enable_fbc >= 0)
> >  		return !!i915.enable_fbc;
> >  
> > +	if (!HAS_FBC(dev_priv))
> > +		return 0;
> > +
> >  	if (IS_BROADWELL(dev_priv))
> >  		return 1;
> >  
> >  	return 0;
> >  }
> >  
> > +static bool need_fbc_wa(struct drm_i915_private *dev_priv)
> > +{
> > +#ifdef CONFIG_INTEL_IOMMU
> > +	/* WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl */
> > +	if (intel_iommu_gfx_mapped && IS_SKYLAKE(dev_priv)) {
> > +		DRM_INFO("Disabling framebuffer compression (FBC) to prevent screen flicker with VT-d enabled\n");
> > +		return true;
> > +	}
> > +#endif
> > +
> > +	return false;
> > +}
> > +
> >  /**
> >   * intel_fbc_init - Initialize FBC
> >   * @dev_priv: the i915 device
> > @@ -1252,6 +1268,9 @@ void intel_fbc_init(struct drm_i915_private *dev_priv)
> >  	fbc->active = false;
> >  	fbc->work.scheduled = false;
> >  
> > +	if (need_fbc_wa(dev_priv))
> > +		mkwrite_device_info(dev_priv)->has_fbc = false;
> > +
> >  	i915.enable_fbc = intel_sanitize_fbc_option(dev_priv);
> >  	DRM_DEBUG_KMS("Sanitized enable_fbc value: %d\n", i915.enable_fbc);
> 
> -- 
> Jani Nikula, Intel Open Source Technology Center
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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