[PATCH] drm/i915: no LVDS on Intel SandyBridge SDVs

[PATCH] drm/i915: no LVDS on Intel SandyBridge SDVs

[Jesse Barnes]

Add a DMI match entry for the SDV to indicate it has no LVDS present.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

diff --git a/drivers/gpu/drm/i915/intel_lvds.c b/drivers/gpu/drm/i915/intel_lvds.c
index aa23070..2f383f0 100644
--- a/drivers/gpu/drm/i915/intel_lvds.c
+++ b/drivers/gpu/drm/i915/intel_lvds.c
@@ -719,6 +719,14 @@ static const struct dmi_system_id intel_no_lvds[] = {
 			DMI_MATCH(DMI_PRODUCT_NAME, "U800"),
 		},
 	},
+	{
+		.callback = intel_no_lvds_dmi_callback,
+		.ident = "Intel SandyBridge",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Intel Corporation"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "SandyBridge Platform"),
+		},
+	},
 
 	{ }	/* terminating entry */
 };

Re: [PATCH] drm/i915: no LVDS on Intel SandyBridge SDVs

[Chris Wilson]

On Mon, 20 Dec 2010 12:05:40 -0800, Jesse Barnes <jbarnes@virtuousgeek.org> wrote:
> Add a DMI match entry for the SDV to indicate it has no LVDS present.
> 
> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

https://bugzilla.kernel.org/show_bug.cgi?id=22042

Caveat tester.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre

Re: [PATCH] drm/i915: no LVDS on Intel SandyBridge SDVs

[Dave Airlie]

On Tue, Dec 21, 2010 at 6:05 AM, Jesse Barnes <jbarnes@virtuousgeek.org> wrote:
> Add a DMI match entry for the SDV to indicate it has no LVDS present.

Sounds wrong, generally the SDVs can get an LVDS panel plugged into
them, so they have an LVDS connector.

I'd worry that this would break something upstream that isn't an SDV.

Dave.

>
> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
>
> diff --git a/drivers/gpu/drm/i915/intel_lvds.c b/drivers/gpu/drm/i915/intel_lvds.c
> index aa23070..2f383f0 100644
> --- a/drivers/gpu/drm/i915/intel_lvds.c
> +++ b/drivers/gpu/drm/i915/intel_lvds.c
> @@ -719,6 +719,14 @@ static const struct dmi_system_id intel_no_lvds[] = {
>                        DMI_MATCH(DMI_PRODUCT_NAME, "U800"),
>                },
>        },
> +       {
> +               .callback = intel_no_lvds_dmi_callback,
> +               .ident = "Intel SandyBridge",
> +               .matches = {
> +                       DMI_MATCH(DMI_SYS_VENDOR, "Intel Corporation"),
> +                       DMI_MATCH(DMI_PRODUCT_NAME, "SandyBridge Platform"),
> +               },
> +       },
>
>        { }     /* terminating entry */
>  };
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> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
>

Re: [PATCH] drm/i915: no LVDS on Intel SandyBridge SDVs

[Jesse Barnes]

On Tue, 21 Dec 2010 12:43:38 +1000
Dave Airlie <airlied@gmail.com> wrote:

> On Tue, Dec 21, 2010 at 6:05 AM, Jesse Barnes <jbarnes@virtuousgeek.org> wrote:
> > Add a DMI match entry for the SDV to indicate it has no LVDS present.
> 
> Sounds wrong, generally the SDVs can get an LVDS panel plugged into
> them, so they have an LVDS connector.

Yeah I think there's actually a header on this board for LVDS so it
would be better to have a way to detect that.  I don't know what that
method would be though...

> I'd worry that this would break something upstream that isn't an SDV.

This DMI info is specific to SandyBridge SDVs, I don't think that part
of the BIOS is used as reference for other vendors.

-- 
Jesse Barnes, Intel Open Source Technology Center

Re: [PATCH] drm/i915: no LVDS on Intel SandyBridge SDVs

[Chris Wilson]

On Mon, 20 Dec 2010 18:53:14 -0800, Jesse Barnes <jbarnes@virtuousgeek.org> wrote:
> On Tue, 21 Dec 2010 12:43:38 +1000
> Dave Airlie <airlied@gmail.com> wrote:
> 
> > On Tue, Dec 21, 2010 at 6:05 AM, Jesse Barnes <jbarnes@virtuousgeek.org> wrote:
> > > Add a DMI match entry for the SDV to indicate it has no LVDS present.
> > 
> > Sounds wrong, generally the SDVs can get an LVDS panel plugged into
> > them, so they have an LVDS connector.
> 
> Yeah I think there's actually a header on this board for LVDS so it
> would be better to have a way to detect that.  I don't know what that
> method would be though...

I think once upon a time I found a reliable method in the docs:
intel_lvds_ddc_probe(). However that only seemed to work over GMBUS...

Jesse, can you try disabling bus->force_bit in intel_i2c.c and see if that
probe method still works?
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre

Re: [PATCH] drm/i915: no LVDS on Intel SandyBridge SDVs

[Keith Packard]

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On Tue, 21 Dec 2010 11:36:44 +0000, Chris Wilson <chris@chris-wilson.co.uk> wrote:

> I think once upon a time I found a reliable method in the docs:
> intel_lvds_ddc_probe(). However that only seemed to work over GMBUS...

That probably depends on the panel having DDC, which many don't, right?
Maybe we can assume the SDV panels do?

-- 
keith.packard@intel.com

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Re: [PATCH] drm/i915: no LVDS on Intel SandyBridge SDVs

[Chris Wilson]

On Tue, 21 Dec 2010 10:14:51 -0800, Keith Packard <keithp@keithp.com> wrote:
> On Tue, 21 Dec 2010 11:36:44 +0000, Chris Wilson <chris@chris-wilson.co.uk> wrote:
> 
> > I think once upon a time I found a reliable method in the docs:
> > intel_lvds_ddc_probe(). However that only seemed to work over GMBUS...
> 
> That probably depends on the panel having DDC, which many don't, right?
> Maybe we can assume the SDV panels do?

The test we do is simply whether the LVDS i2c pins are addressable. That
requires differentiating between an IO error and a NAK, which at present
is only possible using GMBUS. The reference to this method I found in the
BIOS writers' guide, but of course that doesn't actually explain how it
works (especially the significance of address 0xa0).
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre

Re: [PATCH] drm/i915: no LVDS on Intel SandyBridge SDVs

[Keith Packard]

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On Tue, 21 Dec 2010 19:55:15 +0000, Chris Wilson <chris@chris-wilson.co.uk> wrote:

> The test we do is simply whether the LVDS i2c pins are addressable. That
> requires differentiating between an IO error and a NAK, which at present
> is only possible using GMBUS. The reference to this method I found in the
> BIOS writers' guide, but of course that doesn't actually explain how it
> works (especially the significance of address 0xa0).

I can't see how that would work without an i2c receiver on the DDC
bus...

But, then, I've been surprised by DDC in the past, so perhaps it's worth
a test on a device that has LVDS but does not have EDID.

-- 
keith.packard@intel.com

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Re: [PATCH] drm/i915: no LVDS on Intel SandyBridge SDVs

[Chris Wilson]

On Tue, 21 Dec 2010 12:12:42 -0800, Keith Packard <keithp@keithp.com> wrote:
> On Tue, 21 Dec 2010 19:55:15 +0000, Chris Wilson <chris@chris-wilson.co.uk> wrote:
> 
> > The test we do is simply whether the LVDS i2c pins are addressable. That
> > requires differentiating between an IO error and a NAK, which at present
> > is only possible using GMBUS. The reference to this method I found in the
> > BIOS writers' guide, but of course that doesn't actually explain how it
> > works (especially the significance of address 0xa0).
> 
> I can't see how that would work without an i2c receiver on the DDC
> bus...
> 
> But, then, I've been surprised by DDC in the past, so perhaps it's worth
> a test on a device that has LVDS but does not have EDID.

It works as far back as I can test, a 915GM without a VBIOS or EDID.
I've had one person report that it can distinguish a phantom LVDS panel on
one g33 based all-in-one computer. Though not all hardware is equal, and
prudence suggests wider testing. ;-)
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre