[PATCH v2] i915: Add option to bypass vbt table.

[PATCH v2] i915: Add option to bypass vbt table.

[Mathias.Froehlich]

From: Mathias Fröhlich <Mathias.Froehlich@web.de>

Add an option to skip reading the mode entries from
the vbt bios tables.
This change enables the use of displays where the vbt table just
contains inappropriate values, but either the vesa defaults or
the video=... modes do something sensible with the attached display.

Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Signed-off-by: Mathias Froehlich <Mathias.Froehlich@web.de>
---
 drivers/gpu/drm/i915/i915_drv.c   |    4 ++--
 drivers/gpu/drm/i915/intel_bios.c |    5 +++++
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 308f819..0975895 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -89,8 +89,8 @@ MODULE_PARM_DESC(lvds_use_ssc,
 int i915_vbt_sdvo_panel_type __read_mostly = -1;
 module_param_named(vbt_sdvo_panel_type, i915_vbt_sdvo_panel_type, int, 0600);
 MODULE_PARM_DESC(vbt_sdvo_panel_type,
-		"Override selection of SDVO panel mode in the VBT "
-		"(default: auto)");
+		"Override/Ignore selection of SDVO panel mode in the VBT "
+		"(-2=ignore, -1=auto [default], index in VBT BIOS table)");
 
 static bool i915_try_reset __read_mostly = true;
 module_param_named(reset, i915_try_reset, bool, 0600);
diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
index 63880e2..7670b09 100644
--- a/drivers/gpu/drm/i915/intel_bios.c
+++ b/drivers/gpu/drm/i915/intel_bios.c
@@ -255,6 +255,11 @@ parse_sdvo_panel_data(struct drm_i915_private *dev_priv,
 	int index;
 
 	index = i915_vbt_sdvo_panel_type;
+	if (index == -2) {
+		DRM_DEBUG_KMS("Ignore SDVO panel mode from BIOS VBT tables.\n");
+		return;
+	}
+
 	if (index == -1) {
 		struct bdb_sdvo_lvds_options *sdvo_lvds_options;
 
-- 
1.7.1

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Re: [PATCH v2] i915: Add option to bypass vbt table.

[Daniel Vetter]

On Thu, Mar 01, 2012 at 06:44:35AM +0100, Mathias.Froehlich@gmx.net wrote:
> From: Mathias Fröhlich <Mathias.Froehlich@web.de>
> 
> Add an option to skip reading the mode entries from
> the vbt bios tables.
> This change enables the use of displays where the vbt table just
> contains inappropriate values, but either the vesa defaults or
> the video=... modes do something sensible with the attached display.
> 
> Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
> Signed-off-by: Mathias Froehlich <Mathias.Froehlich@web.de>

Can you elaborate a bit on why this is required? Is this for a machine
(like the chrome machines) that just lack a vbios? Or do we fail to parse
the vbt in some way?
-Daniel
-- 
Daniel Vetter
Mail: daniel@ffwll.ch
Mobile: +41 (0)79 365 57 48

Re: [PATCH v2] i915: Add option to bypass vbt table.

[Paul Menzel]

[-- Attachment #1.1: Type: text/plain, Size: 1384 bytes --]

Am Donnerstag, den 01.03.2012, 20:38 +0100 schrieb Daniel Vetter:
> On Thu, Mar 01, 2012 at 06:44:35AM +0100, Mathias.Froehlich@gmx.net wrote:
> > From: Mathias Fröhlich <Mathias.Froehlich@web.de>
> > 
> > Add an option to skip reading the mode entries from
> > the vbt bios tables.
> > This change enables the use of displays where the vbt table just
> > contains inappropriate values, but either the vesa defaults or
> > the video=... modes do something sensible with the attached display.
> > 
> > Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
> > Signed-off-by: Mathias Froehlich <Mathias.Froehlich@web.de>
> 
> Can you elaborate a bit on why this is required? Is this for a machine
> (like the chrome machines) that just lack a vbios? Or do we fail to parse
> the vbt in some way?

Pasted from Mathias’ message with the first patch iteration.

Am Mittwoch, den 29.02.2012, 20:34 +0100 schrieb Mathias Fröhlich:
> Attached is a small change to i915 that fixes a customer case that I had in my 
> day job.
> 
> The problem happens with an embedded board that contains vbt bios tables that 
> do not match the attached display.
> Using this change and the appropriate kernel boot command line they are able to 
> use an otherwise completely unusable secondary display on that embedded board.
> 
> Please review. 


Thanks,

Paul

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[-- Attachment #2: Type: text/plain, Size: 159 bytes --]

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Re: [PATCH v2] i915: Add option to bypass vbt table.

[Daniel Vetter]

On Thu, Mar 01, 2012 at 10:41:32PM +0100, Paul Menzel wrote:
> Am Donnerstag, den 01.03.2012, 20:38 +0100 schrieb Daniel Vetter:
> > On Thu, Mar 01, 2012 at 06:44:35AM +0100, Mathias.Froehlich@gmx.net wrote:
> > > From: Mathias Fröhlich <Mathias.Froehlich@web.de>
> > > 
> > > Add an option to skip reading the mode entries from
> > > the vbt bios tables.
> > > This change enables the use of displays where the vbt table just
> > > contains inappropriate values, but either the vesa defaults or
> > > the video=... modes do something sensible with the attached display.
> > > 
> > > Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
> > > Signed-off-by: Mathias Froehlich <Mathias.Froehlich@web.de>
> > 
> > Can you elaborate a bit on why this is required? Is this for a machine
> > (like the chrome machines) that just lack a vbios? Or do we fail to parse
> > the vbt in some way?
> 
> Pasted from Mathias’ message with the first patch iteration.

Ah, that explains things. I've added this to the commit message and queued
it for -next, thanks.
-Daniel

> 
> Am Mittwoch, den 29.02.2012, 20:34 +0100 schrieb Mathias Fröhlich:
> > Attached is a small change to i915 that fixes a customer case that I had in my 
> > day job.
> > 
> > The problem happens with an embedded board that contains vbt bios tables that 
> > do not match the attached display.
> > Using this change and the appropriate kernel boot command line they are able to 
> > use an otherwise completely unusable secondary display on that embedded board.
> > 
> > Please review. 
> 
> 
> Thanks,
> 
> Paul


-- 
Daniel Vetter
Mail: daniel@ffwll.ch
Mobile: +41 (0)79 365 57 48
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Re: [PATCH v2] i915: Add option to bypass vbt table.

[Mathias Fröhlich]

Hi,

On Thursday, March 01, 2012 23:23:43 Daniel Vetter wrote:
> Ah, that explains things. I've added this to the commit message and queued
> it for -next, thanks.

May be the next time I should also include the reason beyond the technical 
details in the commit message.
Thanks for queuing up!

Mathias