diff mbox

[v3,2/3] drm/i915: Consult VBT "LVDS config" bits to determine whether internal LVDS is present

Message ID 20180508140835.20222-1-ville.syrjala@linux.intel.com (mailing list archive)
State New, archived
Headers show

Commit Message

Ville Syrjälä May 8, 2018, 2:08 p.m. UTC
From: Ville Syrjälä <ville.syrjala@linux.intel.com>

VBT seems to have some bits to tell us whether the internal LVDS port
has something hooked up. In theory one might expect the VBT to not have
a child device for the LVDS port if there's no panel hooked up, but
in practice many VBTs still add the child device. The "LVDS config" bits
seem more reliable though, so let's check those.

So far we've used the "LVDS config" bits to check for eDP support on
ILK+, and disable the internal LVDS when the value is 3. That value
is actually documented as "Both internal LVDS and SDVO LVDS", but in
practice it looks to mean "eDP" on all the ilk+ VBTs I've seen. So let's
keep that interpretation, but for pre-ILK we will consider the value
3 to also indicate the presence of the internal LVDS.

Currently we have 25 DMI matches for the "no internal LVDS" quirk. In an
effort to reduce that let's toss in a WARN when the DMI match and VBT
both tell us that the internal LVDS is not present. The hope is that
people will report a bug, and then we can just nuke the corresponding
entry from the DMI quirk list. Credits to Jani for this idea.

v2: Split the basic int_lvds_support thing to a separate patch (Jani)
v3: Rebase

Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Ondrej Zary <linux@rainbow-software.org>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105468
References: https://lists.freedesktop.org/archives/intel-gfx/2018-March/158408.html
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/i915/intel_bios.c     | 16 +++++++++++++---
 drivers/gpu/drm/i915/intel_lvds.c     |  5 ++++-
 drivers/gpu/drm/i915/intel_vbt_defs.h |  2 +-
 3 files changed, 18 insertions(+), 5 deletions(-)

Comments

Jani Nikula May 8, 2018, 2:22 p.m. UTC | #1
On Tue, 08 May 2018, Ville Syrjala <ville.syrjala@linux.intel.com> wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> VBT seems to have some bits to tell us whether the internal LVDS port
> has something hooked up. In theory one might expect the VBT to not have
> a child device for the LVDS port if there's no panel hooked up, but
> in practice many VBTs still add the child device. The "LVDS config" bits
> seem more reliable though, so let's check those.
>
> So far we've used the "LVDS config" bits to check for eDP support on
> ILK+, and disable the internal LVDS when the value is 3. That value
> is actually documented as "Both internal LVDS and SDVO LVDS", but in
> practice it looks to mean "eDP" on all the ilk+ VBTs I've seen. So let's
> keep that interpretation, but for pre-ILK we will consider the value
> 3 to also indicate the presence of the internal LVDS.
>
> Currently we have 25 DMI matches for the "no internal LVDS" quirk. In an
> effort to reduce that let's toss in a WARN when the DMI match and VBT
> both tell us that the internal LVDS is not present. The hope is that
> people will report a bug, and then we can just nuke the corresponding
> entry from the DMI quirk list. Credits to Jani for this idea.
>
> v2: Split the basic int_lvds_support thing to a separate patch (Jani)
> v3: Rebase
>
> Cc: Jani Nikula <jani.nikula@intel.com>
> Cc: Ondrej Zary <linux@rainbow-software.org>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105468
> References: https://lists.freedesktop.org/archives/intel-gfx/2018-March/158408.html
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

Reviewed-by: Jani Nikula <jani.nikula@intel.com>

> ---
>  drivers/gpu/drm/i915/intel_bios.c     | 16 +++++++++++++---
>  drivers/gpu/drm/i915/intel_lvds.c     |  5 ++++-
>  drivers/gpu/drm/i915/intel_vbt_defs.h |  2 +-
>  3 files changed, 18 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
> index 62cc9d3e20f5..f3545b5aabbc 100644
> --- a/drivers/gpu/drm/i915/intel_bios.c
> +++ b/drivers/gpu/drm/i915/intel_bios.c
> @@ -518,9 +518,19 @@ parse_driver_features(struct drm_i915_private *dev_priv,
>  	if (!driver)
>  		return;
>  
> -	if (INTEL_GEN(dev_priv) >= 5 &&
> -	    driver->lvds_config == BDB_DRIVER_FEATURE_EDP)
> -		dev_priv->vbt.int_lvds_support = 0;
> +	if (INTEL_GEN(dev_priv) >= 5) {
> +		/*
> +		 * Note that we consider BDB_DRIVER_FEATURE_INT_SDVO_LVDS
> +		 * to mean "eDP". The VBT spec doesn't agree with that
> +		 * interpretation, but real world VBTs seem to.
> +		 */
> +		if (driver->lvds_config != BDB_DRIVER_FEATURE_INT_LVDS)
> +			dev_priv->vbt.int_lvds_support = 0;
> +	} else {
> +		if (driver->lvds_config != BDB_DRIVER_FEATURE_INT_LVDS &&
> +		    driver->lvds_config != BDB_DRIVER_FEATURE_INT_SDVO_LVDS)
> +			dev_priv->vbt.int_lvds_support = 0;
> +	}
>  
>  	DRM_DEBUG_KMS("DRRS State Enabled:%d\n", driver->drrs_enabled);
>  	/*
> diff --git a/drivers/gpu/drm/i915/intel_lvds.c b/drivers/gpu/drm/i915/intel_lvds.c
> index 05d012358df8..5e5a77927369 100644
> --- a/drivers/gpu/drm/i915/intel_lvds.c
> +++ b/drivers/gpu/drm/i915/intel_lvds.c
> @@ -962,8 +962,11 @@ void intel_lvds_init(struct drm_i915_private *dev_priv)
>  		return;
>  
>  	/* Skip init on machines we know falsely report LVDS */
> -	if (dmi_check_system(intel_no_lvds))
> +	if (dmi_check_system(intel_no_lvds)) {
> +		WARN(!dev_priv->vbt.int_lvds_support,
> +		     "Useless DMI match. Internal LVDS support disabled by VBT\n");
>  		return;
> +	}
>  
>  	if (!dev_priv->vbt.int_lvds_support) {
>  		DRM_DEBUG_KMS("Internal LVDS support disabled by VBT\n");
> diff --git a/drivers/gpu/drm/i915/intel_vbt_defs.h b/drivers/gpu/drm/i915/intel_vbt_defs.h
> index 458468237b5f..39c804624179 100644
> --- a/drivers/gpu/drm/i915/intel_vbt_defs.h
> +++ b/drivers/gpu/drm/i915/intel_vbt_defs.h
> @@ -635,7 +635,7 @@ struct bdb_sdvo_lvds_options {
>  #define BDB_DRIVER_FEATURE_NO_LVDS		0
>  #define BDB_DRIVER_FEATURE_INT_LVDS		1
>  #define BDB_DRIVER_FEATURE_SDVO_LVDS		2
> -#define BDB_DRIVER_FEATURE_EDP			3
> +#define BDB_DRIVER_FEATURE_INT_SDVO_LVDS	3
>  
>  struct bdb_driver_features {
>  	u8 boot_dev_algorithm:1;
Ville Syrjälä May 16, 2018, 2:34 p.m. UTC | #2
On Tue, May 08, 2018 at 05:08:35PM +0300, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> VBT seems to have some bits to tell us whether the internal LVDS port
> has something hooked up. In theory one might expect the VBT to not have
> a child device for the LVDS port if there's no panel hooked up, but
> in practice many VBTs still add the child device. The "LVDS config" bits
> seem more reliable though, so let's check those.
> 
> So far we've used the "LVDS config" bits to check for eDP support on
> ILK+, and disable the internal LVDS when the value is 3. That value
> is actually documented as "Both internal LVDS and SDVO LVDS", but in
> practice it looks to mean "eDP" on all the ilk+ VBTs I've seen. So let's
> keep that interpretation, but for pre-ILK we will consider the value
> 3 to also indicate the presence of the internal LVDS.
> 
> Currently we have 25 DMI matches for the "no internal LVDS" quirk. In an
> effort to reduce that let's toss in a WARN when the DMI match and VBT
> both tell us that the internal LVDS is not present. The hope is that
> people will report a bug, and then we can just nuke the corresponding
> entry from the DMI quirk list. Credits to Jani for this idea.
> 
> v2: Split the basic int_lvds_support thing to a separate patch (Jani)
> v3: Rebase
> 
> Cc: Jani Nikula <jani.nikula@intel.com>
> Cc: Ondrej Zary <linux@rainbow-software.org>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105468
> References: https://lists.freedesktop.org/archives/intel-gfx/2018-March/158408.html
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_bios.c     | 16 +++++++++++++---
>  drivers/gpu/drm/i915/intel_lvds.c     |  5 ++++-
>  drivers/gpu/drm/i915/intel_vbt_defs.h |  2 +-
>  3 files changed, 18 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
> index 62cc9d3e20f5..f3545b5aabbc 100644
> --- a/drivers/gpu/drm/i915/intel_bios.c
> +++ b/drivers/gpu/drm/i915/intel_bios.c
> @@ -518,9 +518,19 @@ parse_driver_features(struct drm_i915_private *dev_priv,
>  	if (!driver)
>  		return;
>  
> -	if (INTEL_GEN(dev_priv) >= 5 &&
> -	    driver->lvds_config == BDB_DRIVER_FEATURE_EDP)
> -		dev_priv->vbt.int_lvds_support = 0;
> +	if (INTEL_GEN(dev_priv) >= 5) {
> +		/*
> +		 * Note that we consider BDB_DRIVER_FEATURE_INT_SDVO_LVDS
> +		 * to mean "eDP". The VBT spec doesn't agree with that
> +		 * interpretation, but real world VBTs seem to.
> +		 */
> +		if (driver->lvds_config != BDB_DRIVER_FEATURE_INT_LVDS)
> +			dev_priv->vbt.int_lvds_support = 0;
> +	} else {
> +		if (driver->lvds_config != BDB_DRIVER_FEATURE_INT_LVDS &&
> +		    driver->lvds_config != BDB_DRIVER_FEATURE_INT_SDVO_LVDS)
> +			dev_priv->vbt.int_lvds_support = 0;

Ugh. Actually we can't do this. I have a 85x machine myself that
has an LVDS panel but the VBT LVDS config bits set to 0 :(

Looking at the revision history in some VBT spec, I see a note 
"0.92 | Add two definitions for VBT value of LVDS Active Config
(00b and 11b values defined) | 06/13/2005". Unfortunately no
information which VBT version this corresponds with.

I do have a 945gm machine with VBT version 134 that does have the
LVDS config bits correctly populated. I believe the 2005 date does
correspond pretty well with the release of 945 chipsets, so 945gm
might be the first platform where we can actually trust this.

So I think we either have to just scrap this patch or limit it
either to 945+ or VBT versions >= 134 (and we could refine that
later if we discover older versions that have the bits populated
already).

As to the bug report that started this whole thing, I think I'll
just go ahead an apply the DMI quirk patch as that's a 85x machine
and clearly we can't use the VBT information there.

> +	}
>  
>  	DRM_DEBUG_KMS("DRRS State Enabled:%d\n", driver->drrs_enabled);
>  	/*
> diff --git a/drivers/gpu/drm/i915/intel_lvds.c b/drivers/gpu/drm/i915/intel_lvds.c
> index 05d012358df8..5e5a77927369 100644
> --- a/drivers/gpu/drm/i915/intel_lvds.c
> +++ b/drivers/gpu/drm/i915/intel_lvds.c
> @@ -962,8 +962,11 @@ void intel_lvds_init(struct drm_i915_private *dev_priv)
>  		return;
>  
>  	/* Skip init on machines we know falsely report LVDS */
> -	if (dmi_check_system(intel_no_lvds))
> +	if (dmi_check_system(intel_no_lvds)) {
> +		WARN(!dev_priv->vbt.int_lvds_support,
> +		     "Useless DMI match. Internal LVDS support disabled by VBT\n");
>  		return;
> +	}
>  
>  	if (!dev_priv->vbt.int_lvds_support) {
>  		DRM_DEBUG_KMS("Internal LVDS support disabled by VBT\n");
> diff --git a/drivers/gpu/drm/i915/intel_vbt_defs.h b/drivers/gpu/drm/i915/intel_vbt_defs.h
> index 458468237b5f..39c804624179 100644
> --- a/drivers/gpu/drm/i915/intel_vbt_defs.h
> +++ b/drivers/gpu/drm/i915/intel_vbt_defs.h
> @@ -635,7 +635,7 @@ struct bdb_sdvo_lvds_options {
>  #define BDB_DRIVER_FEATURE_NO_LVDS		0
>  #define BDB_DRIVER_FEATURE_INT_LVDS		1
>  #define BDB_DRIVER_FEATURE_SDVO_LVDS		2
> -#define BDB_DRIVER_FEATURE_EDP			3
> +#define BDB_DRIVER_FEATURE_INT_SDVO_LVDS	3
>  
>  struct bdb_driver_features {
>  	u8 boot_dev_algorithm:1;
> -- 
> 2.16.1
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
diff mbox

Patch

diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
index 62cc9d3e20f5..f3545b5aabbc 100644
--- a/drivers/gpu/drm/i915/intel_bios.c
+++ b/drivers/gpu/drm/i915/intel_bios.c
@@ -518,9 +518,19 @@  parse_driver_features(struct drm_i915_private *dev_priv,
 	if (!driver)
 		return;
 
-	if (INTEL_GEN(dev_priv) >= 5 &&
-	    driver->lvds_config == BDB_DRIVER_FEATURE_EDP)
-		dev_priv->vbt.int_lvds_support = 0;
+	if (INTEL_GEN(dev_priv) >= 5) {
+		/*
+		 * Note that we consider BDB_DRIVER_FEATURE_INT_SDVO_LVDS
+		 * to mean "eDP". The VBT spec doesn't agree with that
+		 * interpretation, but real world VBTs seem to.
+		 */
+		if (driver->lvds_config != BDB_DRIVER_FEATURE_INT_LVDS)
+			dev_priv->vbt.int_lvds_support = 0;
+	} else {
+		if (driver->lvds_config != BDB_DRIVER_FEATURE_INT_LVDS &&
+		    driver->lvds_config != BDB_DRIVER_FEATURE_INT_SDVO_LVDS)
+			dev_priv->vbt.int_lvds_support = 0;
+	}
 
 	DRM_DEBUG_KMS("DRRS State Enabled:%d\n", driver->drrs_enabled);
 	/*
diff --git a/drivers/gpu/drm/i915/intel_lvds.c b/drivers/gpu/drm/i915/intel_lvds.c
index 05d012358df8..5e5a77927369 100644
--- a/drivers/gpu/drm/i915/intel_lvds.c
+++ b/drivers/gpu/drm/i915/intel_lvds.c
@@ -962,8 +962,11 @@  void intel_lvds_init(struct drm_i915_private *dev_priv)
 		return;
 
 	/* Skip init on machines we know falsely report LVDS */
-	if (dmi_check_system(intel_no_lvds))
+	if (dmi_check_system(intel_no_lvds)) {
+		WARN(!dev_priv->vbt.int_lvds_support,
+		     "Useless DMI match. Internal LVDS support disabled by VBT\n");
 		return;
+	}
 
 	if (!dev_priv->vbt.int_lvds_support) {
 		DRM_DEBUG_KMS("Internal LVDS support disabled by VBT\n");
diff --git a/drivers/gpu/drm/i915/intel_vbt_defs.h b/drivers/gpu/drm/i915/intel_vbt_defs.h
index 458468237b5f..39c804624179 100644
--- a/drivers/gpu/drm/i915/intel_vbt_defs.h
+++ b/drivers/gpu/drm/i915/intel_vbt_defs.h
@@ -635,7 +635,7 @@  struct bdb_sdvo_lvds_options {
 #define BDB_DRIVER_FEATURE_NO_LVDS		0
 #define BDB_DRIVER_FEATURE_INT_LVDS		1
 #define BDB_DRIVER_FEATURE_SDVO_LVDS		2
-#define BDB_DRIVER_FEATURE_EDP			3
+#define BDB_DRIVER_FEATURE_INT_SDVO_LVDS	3
 
 struct bdb_driver_features {
 	u8 boot_dev_algorithm:1;