2011-05-10 21:20:44

by Patrik Jakobsson

[permalink] [raw]
Subject: [PATCH] gma500: Add option to disable LVDS

This patch adds the option to load the driver without LVDS support. Some platforms with the gma500 have nothing hooked up to LVDS but only uses SDVO. LVDS is still detected and added as an encoder which causes SDVO mode-setting to fail.

Signed-off-by: Patrik Jakobsson <[email protected]>
---

diff --git a/drivers/staging/gma500/psb_drv.c b/drivers/staging/gma500/psb_drv.c
index 46ab028..f1c9f07 100644
--- a/drivers/staging/gma500/psb_drv.c
+++ b/drivers/staging/gma500/psb_drv.c
@@ -39,15 +39,18 @@ int drm_psb_debug;
static int drm_psb_trap_pagefaults;

int drm_psb_no_fb;
+int drm_psb_no_lvds;

static int psb_probe(struct pci_dev *pdev, const struct pci_device_id *ent);

MODULE_PARM_DESC(debug, "Enable debug output");
MODULE_PARM_DESC(no_fb, "Disable FBdev");
MODULE_PARM_DESC(trap_pagefaults, "Error and reset on MMU pagefaults");
+MODULE_PARM_DESC(no_lvds, "Disable LVDS");
module_param_named(debug, drm_psb_debug, int, 0600);
module_param_named(no_fb, drm_psb_no_fb, int, 0600);
module_param_named(trap_pagefaults, drm_psb_trap_pagefaults, int, 0600);
+module_param_named(no_lvds, drm_psb_no_lvds, int, 0600);


static struct pci_device_id pciidlist[] = {
@@ -663,7 +666,9 @@ static int psb_driver_load(struct drm_device *dev, unsigned long chipset)
drm_kms_helper_poll_init(dev);
}

- ret = psb_backlight_init(dev);
+ if (!drm_psb_no_lvds)
+ ret = psb_backlight_init(dev);
+
if (ret)
return ret;
#if 0
diff --git a/drivers/staging/gma500/psb_drv.h b/drivers/staging/gma500/psb_drv.h
index e19a454..4593c80 100644
--- a/drivers/staging/gma500/psb_drv.h
+++ b/drivers/staging/gma500/psb_drv.h
@@ -671,6 +671,7 @@ extern int psb_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf);
extern int drm_psb_debug;
extern int drm_psb_no_fb;
extern int drm_idle_check_interval;
+extern int drm_psb_no_lvds;

#define PSB_DEBUG_GENERAL(_fmt, _arg...) \
PSB_DEBUG(PSB_D_GENERAL, _fmt, ##_arg)
diff --git a/drivers/staging/gma500/psb_fb.c b/drivers/staging/gma500/psb_fb.c
index ae097cd..7c00952 100644
--- a/drivers/staging/gma500/psb_fb.c
+++ b/drivers/staging/gma500/psb_fb.c
@@ -719,7 +719,8 @@ static void psb_setup_outputs(struct drm_device *dev)
else
DRM_ERROR("DSI is not supported\n");
} else {
- psb_intel_lvds_init(dev, &dev_priv->mode_dev);
+ if (!drm_psb_no_lvds)
+ psb_intel_lvds_init(dev, &dev_priv->mode_dev);
psb_intel_sdvo_init(dev, SDVOB);
}


2011-05-10 21:44:47

by Alan

[permalink] [raw]
Subject: Re: [PATCH] gma500: Add option to disable LVDS

On Tue, 10 May 2011 23:20:38 +0200
Patrik Jakobsson <[email protected]> wrote:

> This patch adds the option to load the driver without LVDS support. Some platforms with the gma500 have nothing hooked up to LVDS but only uses SDVO. LVDS is still detected and added as an encoder which causes SDVO mode-setting to fail.
>
> Signed-off-by: Patrik Jakobsson <[email protected]>

What platform is this - I'd really like to keep such things automatic and
also if possible make the code handle the case not blow up. The user
shouldn't have to deal with such funnies.

Alan

2011-05-10 21:59:30

by Greg KH

[permalink] [raw]
Subject: Re: [PATCH] gma500: Add option to disable LVDS

On Tue, May 10, 2011 at 10:46:02PM +0100, Alan Cox wrote:
> On Tue, 10 May 2011 23:20:38 +0200
> Patrik Jakobsson <[email protected]> wrote:
>
> > This patch adds the option to load the driver without LVDS support. Some platforms with the gma500 have nothing hooked up to LVDS but only uses SDVO. LVDS is still detected and added as an encoder which causes SDVO mode-setting to fail.
> >
> > Signed-off-by: Patrik Jakobsson <[email protected]>
>
> What platform is this - I'd really like to keep such things automatic and
> also if possible make the code handle the case not blow up. The user
> shouldn't have to deal with such funnies.

I agree, there should be a way to automatically detect this, we don't
need another-module-parameter for something like this if at all
possible.

thanks,

greg k-h

2011-05-10 23:18:10

by Patrik Jakobsson

[permalink] [raw]
Subject: Re: [PATCH] gma500: Add option to disable LVDS

On Tue, May 10, 2011 at 11:46 PM, Alan Cox <[email protected]> wrote:
> On Tue, 10 May 2011 23:20:38 +0200
> Patrik Jakobsson <[email protected]> wrote:
>
>> This patch adds the option to load the driver without LVDS support. Some platforms with the gma500 have nothing hooked up to LVDS but only uses SDVO. LVDS is still detected and added as an encoder which causes SDVO mode-setting to fail.
>>
>> Signed-off-by: Patrik Jakobsson <[email protected]>
>
> What platform is this - I'd really like to keep such things automatic and
> also if possible make the code handle the case not blow up. The user
> shouldn't have to deal with such funnies.
>
> Alan
>

This is for the FIT-PC2.

I agree, it's not a good way to handle it, but since I haven't been
able to pinpoint the problem (and this is staging) it's something that
works for now. Perhaps a nicer way to get around it is by checking
against the dmi system id. That way it would be transparent to the
user. But you might prefer we fix the real problem instead of hacking
around it.

When both LVDS and SDVO is enabled the driver tries to set up both
pipes and LVDS only finds a bogus mode of 0x0 pixels. Not sure why
LVDS takes over instead of SDVO since it has valid modes, but my
screen just goes into powersave when no proper PLL can be set for the
bogus mode.

I'll do some more debugging tomorrow.

2011-05-11 15:50:29

by Alan

[permalink] [raw]
Subject: Re: [PATCH] gma500: Add option to disable LVDS

> pipes and LVDS only finds a bogus mode of 0x0 pixels. Not sure why
> LVDS takes over instead of SDVO since it has valid modes, but my
> screen just goes into powersave when no proper PLL can be set for the
> bogus mode.

Well that is hopeful. If we get a bogus 0x0 pixel mode it means it did
detect something invalid but for some reason we didn't punt on it.

Alan

2011-05-11 16:31:50

by Patrik Jakobsson

[permalink] [raw]
Subject: Re: [PATCH] gma500: Add option to disable LVDS

On Wed, May 11, 2011 at 10:10:22AM +0100, Alan Cox wrote:
> > pipes and LVDS only finds a bogus mode of 0x0 pixels. Not sure why
> > LVDS takes over instead of SDVO since it has valid modes, but my
> > screen just goes into powersave when no proper PLL can be set for the
> > bogus mode.
>
> Well that is hopeful. If we get a bogus 0x0 pixel mode it means it did
> detect something invalid but for some reason we didn't punt on it.
>
> Alan

I've tried setting mode_config.min_width and height to 1 to get rid of the
mode but no luck there.

Been probing the display registers and the only difference is that pipe b is
disabled when lvds is disabled.

As can be seen in the dmesg output, there are 5 correct modes for SDVO but the
display supports up to 1920x1200 so there is something wrong with the SDVO
probing. Will dig into that later this week.

Below is the output from a regdumper I wrote. LVDS is enabled at this point.

-------- gma500 regdump version 0.1 --------

Probing for hardware: Found gma500 and SCH

PCI config registers:
GMEM_BASE: 0xc0000000
GTT_BASE: 0xc0000000
GC 0x30
GMS: 0x3 (8 MB of pre-allocated framebuffer)
VD: 0x0 (VGA is enabled)
BSM: 0x3f800000
MSAC: 0x2 (256 MB aperture)
GCR: 0x1ff0006
GC2D: 0x1 (ratio is 2:1)
GCCR: 0x2 (ratio is 3:2)
ASLS: 0x3f6bccbd

Pipe A:
HTOTAL: 0x53f03ff (Active: 1024, Total: 1344)
HBLANK: 0x53f03ff (Start: 1024, End: 1344)
HSYNC: 0x49f0417 (Start: 1048, End: 1184)
VTOTAL: 0x32502ff (Active: 768, Total: 806)
VBLANK: 0x32502ff (Start: 768, End: 806)
VSYNC: 0x3080302 (Start: 771, End: 777)
PIPESRC: 0x3ff02ff (Width: 1024, Height: 768)
BCLRPAT: 0x0
VSYNCSHIFT: 0x0
PIPE_DSL: 423
PIPE_SLC: 0
PIPE_CONF: 0x80000000 (Enabled)
State: Disabled
Interlaced mode: No (Progressive)
Bits per color: 8 bits
PIPESTAT: 0x203

Pipe B:
HTOTAL: 0x31f027f (Active: 640, Total: 800)
HBLANK: 0x3170287 (Start: 648, End: 792)
HSYNC: 0x2ef028f (Start: 656, End: 752)
VTOTAL: 0x20c01df (Active: 480, Total: 525)
VBLANK: 0x20401e7 (Start: 488, End: 517)
VSYNC: 0x1eb01e9 (Start: 490, End: 492)
PIPESRC: 0x27f01df (Width: 640, Height: 480)
BCLRPAT: 0x0
VSYNCSHIFT: 0x0
PIPE_DSL: 185
PIPE_SLC: 0
PIPE_CONF: 0x80000000 (Enabled)
State: Disabled
Interlaced mode: No (Progressive)
Bits per color: 8 bits
PIPESTAT: 0x80000202

DPLL A:
VCO Enabled: Yes
SDVO Enabled: Yes
VGA Disabled: Yes
Mode select: DAC / SDVO / UDI / TV
P2 DIV: 0x0
P1 DIV: 0x1
Reference input select: DREFCLK (default is 96 MHz)

FPA0: 0x30b06
Freq doubler: Disabled
N divisor: 5
M1 divisor: 13
M2 divisor: 8

FPA1: 0x31108
N divisor: 5
M1 divisor: 19
M2 divisor: 10

DPLL B:
VCO Enabled: Yes
SDVO Enabled: No
VGA Disabled: No
Mode select: DAC / SDVO / UDI / TV
P2 DIV: 0x0
P1 DIV: 0x80
Reference input select: DREFCLK (default is 96 MHz)

FPB0: 0x31108
Freq doubler: Disabled
N divisor: 5
M1 divisor: 19
M2 divisor: 10

FPB1: 0x31108
N divisor: 5
M1 divisor: 19
M2 divisor: 10

SDVOB: 0x80480080
Enabled: Yes
Detected: No

SDVOC: 0x0
Enabled: No
Detected: No


Here's the dmesg with drm_debug=7, LVDS is also enabled here.

-----------------------------------------------------------

[ 165.101334] Linux agpgart interface v0.103
[ 165.260816] [drm] Initialized drm 1.1.0 20060810
[ 165.355994] psb_gfx: module is from the staging directory, the quality is unknown, you have been warned.
[ 165.380626] [drm:drm_pci_init],
[ 165.380737] pvrsrvkm 0000:00:02.0: irq 41 for MSI/MSI-X
[ 165.380752] [drm:drm_get_pci_dev],
[ 165.380777] pvrsrvkm 0000:00:02.0: setting latency timer to 64
[ 165.380830] [drm:drm_get_minor],
[ 165.381208] [drm:drm_get_minor], new minor assigned 64
[ 165.381219] [drm:drm_get_minor],
[ 165.382626] [drm:drm_get_minor], new minor assigned 0
[ 165.382863] [drm:psb_intel_opregion_init], OpRegion detected at 0x3f6bccbd
[ 165.382884] ioremap error for 0x3f6bc000-0x3f6bf000, requested 0x10, got 0x0
[ 165.383050] [drm:parse_lfp_panel_data], Found panel mode in BIOS VBT tables:
[ 165.383060] [drm:drm_mode_debug_printmodeline], Modeline 0:"0x0" 0 0 0 0 0 0 0 0 0 0 0x8 0x0
[ 165.383077] [drm:parse_backlight_data], lvds_options found at c00c15f2
[ 165.383491] GMMADR(region 0) start: 0xc0000000 (256M).
[ 165.383501] GTTADR(region 3) start: 0xb0000000 (can map 256M RAM), and actual RAM base 0x3ffc0000.
[ 165.383508] Stolen memory information
[ 165.383514] base in RAM: 0x3f800000
[ 165.383520] size: 7932K, calculated by (GTT RAM base) - (Stolen base), seems wrong
[ 165.383528] the correct size should be: 8M(dvmt mode=3)
[ 165.386044] [drm:psb_gtt_init], [: vram kernel virtual address 00000010
[ 165.386063] Set up 1983 stolen pages starting at 0x0003f800, GTT offset 0K
[ 165.387847] [drm] SGX core id = 0x01130000
[ 165.387854] [drm] SGX core rev major = 0x01, minor = 0x02
[ 165.387858] [drm] SGX core rev maintenance = 0x01, designer = 0x00
[ 165.400238] [drm] Supports vblank timestamp caching Rev 1 (10.10.2010).
[ 165.400255] [drm] No driver support for vblank timestamp query.
[ 165.400270] [drm:drm_irq_install], irq=41
[ 165.450788] [drm:drm_sysfs_connector_add], adding "LVDS-1" to sysfs
[ 165.450876] [drm:drm_sysfs_hotplug_event], generating hotplug event
[ 165.736102] [drm:drm_sysfs_connector_add], adding "DVI-D-1" to sysfs
[ 165.736184] [drm:drm_sysfs_hotplug_event], generating hotplug event
[ 165.768328] [drm:psb_intel_sdvo_init], SDVOB device VID/DID: 02:3C.06, clock range 25MHz - 200MHz, input 1: Y, input 2: N, output 1: Y, output 2: N
[ 165.821104] [drm:drm_helper_probe_single_connector_modes], [CONNECTOR:7:LVDS-1]
[ 165.869395] [drm:drm_helper_probe_single_connector_modes], [CONNECTOR:7:LVDS-1] probed modes :
[ 165.869404] [drm:drm_mode_debug_printmodeline], Modeline 12:"0x0" 0 0 0 0 0 0 0 0 0 0 0x8 0x0
[ 165.869415] [drm:drm_helper_probe_single_connector_modes], [CONNECTOR:10:DVI-D-1]
[ 165.883967] [drm:psb_intel_sdvo_detect], SDVO response 1 0
[ 165.916232] [drm:drm_helper_probe_single_connector_modes], [CONNECTOR:10:DVI-D-1] probed modes :
[ 165.916241] [drm:drm_mode_debug_printmodeline], Modeline 17:"1024x768" 60 65000 1024 1048 1184 1344 768 771 777 806 0x40 0xa
[ 165.916253] [drm:drm_mode_debug_printmodeline], Modeline 15:"800x600" 60 40000 800 840 968 1056 600 601 605 628 0x40 0x5
[ 165.916264] [drm:drm_mode_debug_printmodeline], Modeline 14:"800x600" 56 36000 800 824 896 1024 600 601 603 625 0x40 0x5
[ 165.916275] [drm:drm_mode_debug_printmodeline], Modeline 16:"848x480" 60 33750 848 864 976 1088 480 486 494 517 0x40 0x5
[ 165.916285] [drm:drm_mode_debug_printmodeline], Modeline 13:"640x480" 60 25175 640 656 752 800 480 489 492 525 0x40 0xa
[ 165.916296] [drm:drm_setup_crtcs],
[ 165.916302] [drm:drm_enable_connectors], connector 7 enabled? yes
[ 165.916308] [drm:drm_enable_connectors], connector 10 enabled? yes
[ 165.916314] [drm:drm_target_preferred], looking for cmdline mode on connector 7
[ 165.916320] [drm:drm_target_preferred], looking for preferred mode on connector 7
[ 165.916326] [drm:drm_target_preferred], found mode 0x0
[ 165.916331] [drm:drm_target_preferred], looking for cmdline mode on connector 10
[ 165.916337] [drm:drm_target_preferred], looking for preferred mode on connector 10
[ 165.916343] [drm:drm_target_preferred], found mode 1024x768
[ 165.916348] [drm:drm_setup_crtcs], picking CRTCs for 2048x2048 config
[ 165.916357] [drm:drm_setup_crtcs], desired mode 0x0 set on crtc 4
[ 165.916364] [drm:drm_setup_crtcs], desired mode 1024x768 set on crtc 3
[ 165.916372] [drm:psbfb_probe], psbfb_probe
[ 165.919014] [drm:psbfb_create], fb depth is 24
[ 165.919019] [drm:psbfb_create], pitch is 4096
[ 165.919025] allocated 1024x768 fb
[ 165.919193] fbcon: psbfb (fb0) is primary device
[ 165.921717] [drm:drm_crtc_helper_set_config],
[ 165.921726] [drm:drm_crtc_helper_set_config], [CRTC:3] [FB:20] #connectors=1 (x y) (0 0)
[ 165.921748] [drm:drm_crtc_helper_set_config], crtc has no fb, full mode set
[ 165.921756] [drm:drm_crtc_helper_set_config], modes are different, full mode set
[ 165.921764] [drm:drm_mode_debug_printmodeline], Modeline 0:"" 0 0 0 0 0 0 0 0 0 0 0x0 0x0
[ 165.921776] [drm:drm_mode_debug_printmodeline], Modeline 19:"1024x768" 60 65000 1024 1048 1184 1344 768 771 777 806 0x40 0xa
[ 165.921792] [drm:drm_crtc_helper_set_config], encoder changed, full mode switch
[ 165.921800] [drm:drm_crtc_helper_set_config], crtc changed, full mode switch
[ 165.921808] [drm:drm_crtc_helper_set_config], [CONNECTOR:10:DVI-D-1] to [CRTC:3]
[ 165.921817] [drm:drm_crtc_helper_set_config], attempting to set mode from userspace
[ 165.921824] [drm:drm_mode_debug_printmodeline], Modeline 19:"1024x768" 60 65000 1024 1048 1184 1344 768 771 777 806 0x40 0xa
[ 165.921845] [drm:drm_crtc_helper_set_mode], [CRTC:3]
[ 165.954960] [drm:psb_intel_crtc_mode_set], Mode for pipe A:
[ 165.954968] [drm:drm_mode_debug_printmodeline], Modeline 19:"1024x768" 60 65000 1024 1048 1184 1344 768 771 777 806 0x40 0xa
[ 165.975298] [drm:psb_intel_pipe_set_base], Writing base 00000000 00000000 0 0
[ 165.995146] [drm:drm_crtc_helper_set_mode], [ENCODER:11:TMDS-11] set [MODE:19:1024x768]
[ 166.243579] [drm:drm_calc_timestamping_constants], crtc 3: hwmode: htotal 1344, vtotal 806, vdisplay 768
[ 166.243588] [drm:drm_calc_timestamping_constants], crtc 3: clock 130000 kHz framedur 8332428 linedur 10338, pixeldur 7
[ 166.243599] [drm:drm_crtc_helper_set_config], Setting connector DPMS state to on
[ 166.243605] [drm:drm_crtc_helper_set_config], [CONNECTOR:10:DVI-D-1] set DPMS on
[ 166.263610] [drm:drm_crtc_helper_set_config],
[ 166.263614] [drm:drm_crtc_helper_set_config], [CRTC:4] [FB:20] #connectors=1 (x y) (0 0)
[ 166.263637] [drm:drm_crtc_helper_set_config], crtc has no fb, full mode set
[ 166.263643] [drm:drm_crtc_helper_set_config], encoder changed, full mode switch
[ 166.263648] [drm:drm_crtc_helper_set_config], crtc changed, full mode switch
[ 166.263653] [drm:drm_crtc_helper_set_config], [CONNECTOR:7:LVDS-1] to [CRTC:4]
[ 166.263659] [drm:drm_crtc_helper_set_config], [CONNECTOR:10:DVI-D-1] to [CRTC:3]
[ 166.263665] [drm:drm_crtc_helper_set_config], attempting to set mode from userspace
[ 166.263670] [drm:drm_mode_debug_printmodeline], Modeline 18:"0x0" 0 0 0 0 0 0 0 0 0 0 0x8 0x0
[ 166.263683] [drm:drm_crtc_helper_set_mode], [CRTC:4]
[ 166.283862] [drm:psb_intel_crtc_mode_set] *ERROR* Couldn't find PLL settings for mode!
[ 166.283868] [drm:drm_crtc_helper_set_mode], [ENCODER:8:LVDS-8] set [MODE:18:0x0]

2011-05-11 16:58:51

by Matthew Garrett

[permalink] [raw]
Subject: Re: [PATCH] gma500: Add option to disable LVDS

On Wed, May 11, 2011 at 01:18:07AM +0200, Patrik Jakobsson wrote:

> I agree, it's not a good way to handle it, but since I haven't been
> able to pinpoint the problem (and this is staging) it's something that
> works for now. Perhaps a nicer way to get around it is by checking
> against the dmi system id. That way it would be transparent to the
> user. But you might prefer we fix the real problem instead of hacking
> around it.

Assuming the VBT data is anything like 915, it should be possible to
parse LVDS presence that way.

--
Matthew Garrett | [email protected]

2011-05-11 16:20:07

by Kristoffer Ericson

[permalink] [raw]
Subject: Re: [PATCH] gma500: Add option to disable LVDS

On Wed, May 11, 2011 at 01:18:07AM +0200, Patrik Jakobsson wrote:
> On Tue, May 10, 2011 at 11:46 PM, Alan Cox <[email protected]> wrote:
> > On Tue, 10 May 2011 23:20:38 +0200
> > Patrik Jakobsson <[email protected]> wrote:
> >
> >> This patch adds the option to load the driver without LVDS support. Some platforms with the gma500 have nothing hooked up to LVDS but only uses SDVO. LVDS is still detected and added as an encoder which causes SDVO mode-setting to fail.
> >>
> >> Signed-off-by: Patrik Jakobsson <[email protected]>
> >
> > What platform is this - I'd really like to keep such things automatic and
> > also if possible make the code handle the case not blow up. The user
> > shouldn't have to deal with such funnies.
> >
> > Alan
> >
>
> This is for the FIT-PC2.
>
> I agree, it's not a good way to handle it, but since I haven't been
> able to pinpoint the problem (and this is staging) it's something that
> works for now. Perhaps a nicer way to get around it is by checking
> against the dmi system id. That way it would be transparent to the
> user. But you might prefer we fix the real problem instead of hacking
> around it.
>
> When both LVDS and SDVO is enabled the driver tries to set up both
> pipes and LVDS only finds a bogus mode of 0x0 pixels. Not sure why
> LVDS takes over instead of SDVO since it has valid modes, but my
> screen just goes into powersave when no proper PLL can be set for the
> bogus mode.
>
> I'll do some more debugging tomorrow.

Im getting similiar problems although not to that extreme. It defaults back to
lowest common resolution which seems to be 1024x768, so in that sense I would
appreciate being able to turn it off. That being said, its an issue which will
eventually go away and therefore theres little point in implementing a workaround.

Best wishes
Kristoffer

> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to [email protected]
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/

2011-05-11 16:59:59

by Patrik Jakobsson

[permalink] [raw]
Subject: Re: [PATCH] gma500: Add option to disable LVDS

On Wed, May 11, 2011 at 2:41 PM, Patrik Jakobsson
<[email protected]> wrote:
> On Wed, May 11, 2011 at 10:10:22AM +0100, Alan Cox wrote:
>> > pipes and LVDS only finds a bogus mode of 0x0 pixels. Not sure why
>> > LVDS takes over instead of SDVO since it has valid modes, but my
>> > screen just goes into powersave when no proper PLL can be set for the
>> > bogus mode.
>>
>> Well that is hopeful. If we get a bogus 0x0 pixel mode it means it did
>> detect something invalid but for some reason we didn't punt on it.
>>
>> Alan

> Here's the dmesg with drm_debug=7, LVDS is also enabled here.

> [ ?165.383050] [drm:parse_lfp_panel_data], Found panel mode in BIOS VBT tables:
> [ ?165.383060] [drm:drm_mode_debug_printmodeline], Modeline 0:"0x0" 0 0 0 0 0 0 0 0 0 0 0x8 0x0

The mode comes from the video bios table. When skipping the bios probe
I get a working framebuffer but the backlight code crashes so this
needs to be handled.

I'll send a patch that throws away that mode and skips backlight if
there is no lvds ouput.

-Patrik