[PATCH 0/2 v4] drm/i915: LVDS channel mode fixes

[PATCH 0/2 v4] drm/i915: LVDS channel mode fixes

[Takashi Iwai]

Hi,

this is the revised patch for fixing the wrong LVDS channel mode,
e.g. when booted while the lid is closed.  Also, a new module option
to override the LVDS channel mode is added in the second patch.

v1->v2: Fix the register for gen<=4
v2->v3: Check the resolution of the entry to be sure
v3->v4: Optimize the register reference; add a module option

thanks,

Takashi

[PATCH 1/2] drm/i915: Check VBIOS value for determining LVDS dual channel mode, too

[Takashi Iwai]

Currently i915 driver checks [PCH_]LVDS register bits to decide
whether to set up the dual-link or the single-link mode.  This relies
implicitly on that BIOS initializes the register properly at boot.
However, BIOS doesn't initialize it always.  When the machine is
booted with the closed lid, BIOS skips the LVDS reg initialization.
This ends up in blank output on a machine with a dual-link LVDS when
you open the lid after the boot.

This patch adds a workaround for that problem by checking the initial
LVDS register value in VBT.

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 drivers/gpu/drm/i915/i915_drv.h      |    1 +
 drivers/gpu/drm/i915/intel_bios.c    |   26 ++++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_display.c |   26 ++++++++++++++++++++------
 3 files changed, 47 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 9689ca3..8c8e488 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -376,6 +376,7 @@ typedef struct drm_i915_private {
 	unsigned int lvds_use_ssc:1;
 	unsigned int display_clock_mode:1;
 	int lvds_ssc_freq;
+	unsigned int bios_lvds_val; /* initial [PCH_]LVDS reg val in VBIOS */
 	struct {
 		int rate;
 		int lanes;
diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
index 63880e2..6b93f92 100644
--- a/drivers/gpu/drm/i915/intel_bios.c
+++ b/drivers/gpu/drm/i915/intel_bios.c
@@ -173,6 +173,27 @@ get_lvds_dvo_timing(const struct bdb_lvds_lfp_data *lvds_lfp_data,
 	return (struct lvds_dvo_timing *)(entry + dvo_timing_offset);
 }
 
+/* read the initial LVDS register value for the given panel mode */
+static unsigned int get_lvds_reg_val(const struct bdb_header *bdb,
+				     const struct bdb_lvds_lfp_data_ptrs *ptrs,
+				     int index,
+				     struct drm_display_mode *mode)
+{
+	unsigned int ofs;
+	const struct lvds_fp_timing *timing;
+
+	if (index >= ARRAY_SIZE(ptrs->ptr))
+		return 0;
+	ofs = ptrs->ptr[index].fp_timing_offset;
+	if (ofs + sizeof(*timing) > bdb->bdb_size)
+		return 0;
+	timing = (const struct lvds_fp_timing *)((const u8 *)bdb + ofs);
+	/* check the resolution, just to be sure */
+	if (timing->x_res != mode->hdisplay || timing->y_res != mode->vdisplay)
+		return 0;
+	return timing->lvds_reg_val;
+}
+
 /* Try to find integrated panel data */
 static void
 parse_lfp_panel_data(struct drm_i915_private *dev_priv,
@@ -243,6 +264,11 @@ parse_lfp_panel_data(struct drm_i915_private *dev_priv,
 			      "Normal Clock %dKHz, downclock %dKHz\n",
 			      panel_fixed_mode->clock, 10*downclock);
 	}
+
+	dev_priv->bios_lvds_val = get_lvds_reg_val(bdb, lvds_lfp_data_ptrs,
+						   lvds_options->panel_type,
+						   panel_fixed_mode);
+	DRM_DEBUG_KMS("VBT initial LVDS value %x\n", dev_priv->bios_lvds_val);
 }
 
 /* Try to find sdvo panel data */
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index f851db7..d7e6b76 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -356,6 +356,23 @@ static const intel_limit_t intel_limits_ironlake_display_port = {
 	.find_pll = intel_find_pll_ironlake_dp,
 };
 
+static bool is_dual_link_lvds(struct drm_i915_private *dev_priv,
+			      unsigned int reg)
+{
+	unsigned int val;
+	/* BIOS should set the proper LVDS register value at boot, but
+	 * in reality, it doesn't set the value when the lid is closed;
+	 * thus when a machine is booted with the lid closed, the LVDS
+	 * reg value can't be trusted.  So we need to check "the value
+	 * to be set" in VBT at first.
+	 */
+	if (dev_priv->bios_lvds_val)
+		val = dev_priv->bios_lvds_val;
+	else
+		val = I915_READ(reg);
+	return (val & LVDS_CLKB_POWER_MASK) == LVDS_CLKB_POWER_UP;
+}
+
 static const intel_limit_t *intel_ironlake_limit(struct drm_crtc *crtc,
 						int refclk)
 {
@@ -364,8 +381,7 @@ static const intel_limit_t *intel_ironlake_limit(struct drm_crtc *crtc,
 	const intel_limit_t *limit;
 
 	if (intel_pipe_has_type(crtc, INTEL_OUTPUT_LVDS)) {
-		if ((I915_READ(PCH_LVDS) & LVDS_CLKB_POWER_MASK) ==
-		    LVDS_CLKB_POWER_UP) {
+		if (is_dual_link_lvds(dev_priv, PCH_LVDS)) {
 			/* LVDS dual channel */
 			if (refclk == 100000)
 				limit = &intel_limits_ironlake_dual_lvds_100m;
@@ -393,8 +409,7 @@ static const intel_limit_t *intel_g4x_limit(struct drm_crtc *crtc)
 	const intel_limit_t *limit;
 
 	if (intel_pipe_has_type(crtc, INTEL_OUTPUT_LVDS)) {
-		if ((I915_READ(LVDS) & LVDS_CLKB_POWER_MASK) ==
-		    LVDS_CLKB_POWER_UP)
+		if (is_dual_link_lvds(dev_priv, LVDS))
 			/* LVDS with dual channel */
 			limit = &intel_limits_g4x_dual_channel_lvds;
 		else
@@ -531,8 +546,7 @@ intel_find_best_PLL(const intel_limit_t *limit, struct drm_crtc *crtc,
 		 * reliably set up different single/dual channel state, if we
 		 * even can.
 		 */
-		if ((I915_READ(LVDS) & LVDS_CLKB_POWER_MASK) ==
-		    LVDS_CLKB_POWER_UP)
+		if (is_dual_link_lvds(dev_priv, LVDS))
 			clock.p2 = limit->p2.p2_fast;
 		else
 			clock.p2 = limit->p2.p2_slow;
-- 
1.7.9.2

[PATCH 2/2] drm/i915: Add lvds_channel module option

[Takashi Iwai]

Add a new module optoin lvds_channel to specify the LVDS channel mode
explicitly instead of probing the LVDS register value set by BIOS.
This will be helpful when VBT is broken or incompatible with the
current code.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 drivers/gpu/drm/i915/i915_drv.c      |    6 ++++++
 drivers/gpu/drm/i915/i915_drv.h      |    1 +
 drivers/gpu/drm/i915/intel_display.c |    5 +++++
 3 files changed, 12 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 308f819..eee6804 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -80,6 +80,12 @@ MODULE_PARM_DESC(lvds_downclock,
 		"Use panel (LVDS/eDP) downclocking for power savings "
 		"(default: false)");
 
+int i915_lvds_channel __read_mostly;
+module_param_named(lvds_channel, i915_lvds_channel, int, 0400);
+MODULE_PARM_DESC(lvds_channel,
+		 "Specify LVDS channel mode "
+		 "(0=probe BIOS [default], 1=single-channel, 2=dual-channel)");
+
 int i915_panel_use_ssc __read_mostly = -1;
 module_param_named(lvds_use_ssc, i915_panel_use_ssc, int, 0600);
 MODULE_PARM_DESC(lvds_use_ssc,
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 8c8e488..1af2b53 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1014,6 +1014,7 @@ extern int i915_panel_ignore_lid __read_mostly;
 extern unsigned int i915_powersave __read_mostly;
 extern int i915_semaphores __read_mostly;
 extern unsigned int i915_lvds_downclock __read_mostly;
+extern int i915_lvds_channel __read_mostly;
 extern int i915_panel_use_ssc __read_mostly;
 extern int i915_vbt_sdvo_panel_type __read_mostly;
 extern int i915_enable_rc6 __read_mostly;
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index d7e6b76..87a7fb9 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -360,6 +360,11 @@ static bool is_dual_link_lvds(struct drm_i915_private *dev_priv,
 			      unsigned int reg)
 {
 	unsigned int val;
+
+	/* use the module option value if specified */
+	if (i915_lvds_channel > 0)
+		return i915_lvds_channel == 2;
+
 	/* BIOS should set the proper LVDS register value at boot, but
 	 * in reality, it doesn't set the value when the lid is closed;
 	 * thus when a machine is booted with the lid closed, the LVDS
-- 
1.7.9.2

Re: [PATCH 1/2] drm/i915: Check VBIOS value for determining LVDS dual channel mode, too

[Keith Packard]

<#part sign=pgpmime>
On Fri, 16 Mar 2012 22:41:12 +0100, Takashi Iwai <tiwai@suse.de> wrote:

> +/* read the initial LVDS register value for the given panel mode */
> +static unsigned int get_lvds_reg_val(const struct bdb_header *bdb,
> +				     const struct bdb_lvds_lfp_data_ptrs *ptrs,
> +				     int index,
> +				     struct drm_display_mode *mode)

To follow the style of intel_bios.c, I think it would make sense to have
the function:

static const struct lvds_dvo_timing *
get_lvds_fp_timing(const struct bdb_lvds_lfp_data *lvds_lfp_data,
        	   const struct bdb_lvds_lfp_data_ptrs *lvds_lfp_data_ptrs,
                   int index)

then use the results of this in parse_lfp_panel_data, instead of putting
the whole computation into this new function.

I'd also like to see this code only use the BDB value when the LVDS is
disabled at startup time; otherwise, we'll be changing the behavior for
all LVDS users, and as BIOS tables are notoriously unreliable, I fear
that we'll cause a lot more problems than we solve.

-- 
keith.packard@intel.com

Re: [PATCH 2/2] drm/i915: Add lvds_channel module option

[Eugeni Dodonov]

[-- Attachment #1.1: Type: text/plain, Size: 1334 bytes --]

On Fri, Mar 16, 2012 at 18:41, Takashi Iwai <tiwai@suse.de> wrote:

> Add a new module optoin lvds_channel to specify the LVDS channel mode
> explicitly instead of probing the LVDS register value set by BIOS.
> This will be helpful when VBT is broken or incompatible with the
> current code.
>
> Signed-off-by: Takashi Iwai <tiwai@suse.de>
> ---
>  drivers/gpu/drm/i915/i915_drv.c      |    6 ++++++
>  drivers/gpu/drm/i915/i915_drv.h      |    1 +
>  drivers/gpu/drm/i915/intel_display.c |    5 +++++
>  3 files changed, 12 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.c
> b/drivers/gpu/drm/i915/i915_drv.c
> index 308f819..eee6804 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -80,6 +80,12 @@ MODULE_PARM_DESC(lvds_downclock,
>                "Use panel (LVDS/eDP) downclocking for power savings "
>                "(default: false)");
>
> +int i915_lvds_channel __read_mostly;
> +module_param_named(lvds_channel, i915_lvds_channel, int, 0400);
>

As a minor bikeshedding, perhaps this variable would make more sense if
called 'i915_lvds_channel_mode' instead?

I am fine with either spelling though, it just looks more semantically
correct to me. But in any case,

Reviewed-by: Eugeni Dodonov <eugeni.dodonov@intel.com>

-- 
Eugeni Dodonov
<http://eugeni.dodonov.net/>

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Re: [PATCH 1/2] drm/i915: Check VBIOS value for determining LVDS dual channel mode, too

[Takashi Iwai]

At Fri, 16 Mar 2012 16:18:03 -0700,
Keith Packard wrote:
> 
> <#part sign=pgpmime>
> On Fri, 16 Mar 2012 22:41:12 +0100, Takashi Iwai <tiwai@suse.de> wrote:
> 
> > +/* read the initial LVDS register value for the given panel mode */
> > +static unsigned int get_lvds_reg_val(const struct bdb_header *bdb,
> > +				     const struct bdb_lvds_lfp_data_ptrs *ptrs,
> > +				     int index,
> > +				     struct drm_display_mode *mode)
> 
> To follow the style of intel_bios.c, I think it would make sense to have
> the function:
> 
> static const struct lvds_dvo_timing *
> get_lvds_fp_timing(const struct bdb_lvds_lfp_data *lvds_lfp_data,
>         	   const struct bdb_lvds_lfp_data_ptrs *lvds_lfp_data_ptrs,
>                    int index)
> 
> then use the results of this in parse_lfp_panel_data, instead of putting
> the whole computation into this new function.

Well, the LVDS reg data isn't in lvds_dvo_timing but in lvds_fp_timing,
thus you need to look at a different entry in anyway.

> I'd also like to see this code only use the BDB value when the LVDS is
> disabled at startup time; otherwise, we'll be changing the behavior for
> all LVDS users, and as BIOS tables are notoriously unreliable, I fear
> that we'll cause a lot more problems than we solve.

I skipped it to simplify the code, but that'd be safer, indeed.

(Though, the chance of getting a wrong value is fairly small since
 the function verifies whether the resolution of the entry matches
 with the given mode, too.)


thanks,

Takashi

Re: [PATCH 2/2] drm/i915: Add lvds_channel module option

[Takashi Iwai]

At Fri, 16 Mar 2012 22:51:22 -0300,
Eugeni Dodonov wrote:
> 
> [1  <text/plain; ISO-8859-1 (7bit)>]
> On Fri, Mar 16, 2012 at 18:41, Takashi Iwai <tiwai@suse.de> wrote:
> 
> > Add a new module optoin lvds_channel to specify the LVDS channel mode
> > explicitly instead of probing the LVDS register value set by BIOS.
> > This will be helpful when VBT is broken or incompatible with the
> > current code.
> >
> > Signed-off-by: Takashi Iwai <tiwai@suse.de>
> > ---
> >  drivers/gpu/drm/i915/i915_drv.c      |    6 ++++++
> >  drivers/gpu/drm/i915/i915_drv.h      |    1 +
> >  drivers/gpu/drm/i915/intel_display.c |    5 +++++
> >  3 files changed, 12 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_drv.c
> > b/drivers/gpu/drm/i915/i915_drv.c
> > index 308f819..eee6804 100644
> > --- a/drivers/gpu/drm/i915/i915_drv.c
> > +++ b/drivers/gpu/drm/i915/i915_drv.c
> > @@ -80,6 +80,12 @@ MODULE_PARM_DESC(lvds_downclock,
> >                "Use panel (LVDS/eDP) downclocking for power savings "
> >                "(default: false)");
> >
> > +int i915_lvds_channel __read_mostly;
> > +module_param_named(lvds_channel, i915_lvds_channel, int, 0400);
> >
> 
> As a minor bikeshedding, perhaps this variable would make more sense if
> called 'i915_lvds_channel_mode' instead?
> 
> I am fine with either spelling though, it just looks more semantically
> correct to me. But in any case,

OK, I'll fix in the next spin.


thanks,

Takashi

> 
> Reviewed-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
> 
> -- 
> Eugeni Dodonov
> <http://eugeni.dodonov.net/>
> [2  <text/html; ISO-8859-1 (quoted-printable)>]
> 

Re: [PATCH 1/2] drm/i915: Check VBIOS value for determining LVDS dual channel mode, too

[Keith Packard]

<#part sign=pgpmime>
On Sat, 17 Mar 2012 08:59:56 +0100, Takashi Iwai <tiwai@suse.de> wrote:

> Well, the LVDS reg data isn't in lvds_dvo_timing but in lvds_fp_timing,
> thus you need to look at a different entry in anyway.

Right, a parallel function which returns the lvds_fp_timing structure
instead of pulling the data out of it. Just makes the code look more
like the existing stuff. And, if we need more data from the
lvds_fp_timing in the future, we'll have it available directly.

> I skipped it to simplify the code, but that'd be safer, indeed.

Reducing the chances for regressions is my primary concern here; most
people boot their machines with the lid open, so if we avoid the new
code in that case, we'll be more likely to not break things.

-- 
keith.packard@intel.com

Re: [PATCH 1/2] drm/i915: Check VBIOS value for determining LVDS dual channel mode, too

[Takashi Iwai]

At Sat, 17 Mar 2012 12:01:17 -0700,
Keith Packard wrote:
> 
> <#part sign=pgpmime>
> On Sat, 17 Mar 2012 08:59:56 +0100, Takashi Iwai <tiwai@suse.de> wrote:
> 
> > Well, the LVDS reg data isn't in lvds_dvo_timing but in lvds_fp_timing,
> > thus you need to look at a different entry in anyway.
> 
> Right, a parallel function which returns the lvds_fp_timing structure
> instead of pulling the data out of it. Just makes the code look more
> like the existing stuff. And, if we need more data from the
> lvds_fp_timing in the future, we'll have it available directly.

Ah, OK I got your point now.  This makes sense.
I'll rewrite the patch tomorrow.


> > I skipped it to simplify the code, but that'd be safer, indeed.
> 
> Reducing the chances for regressions is my primary concern here; most
> people boot their machines with the lid open, so if we avoid the new
> code in that case, we'll be more likely to not break things.

Yes, that's my biggest concern too.
So I'd really appreciate if anyone else checks whether the patch
doesn't break, at least (and helps sometimes).


thanks,

Takashi

> 
> -- 
> keith.packard@intel.com
> 

Re: [PATCH 0/2 v4] drm/i915: LVDS channel mode fixes

[Adam Jackson]

[-- Attachment #1.1: Type: text/plain, Size: 514 bytes --]

On Fri, 2012-03-16 at 22:41 +0100, Takashi Iwai wrote:
> Hi,
> 
> this is the revised patch for fixing the wrong LVDS channel mode,
> e.g. when booted while the lid is closed.  Also, a new module option
> to override the LVDS channel mode is added in the second patch.
> 
> v1->v2: Fix the register for gen<=4
> v2->v3: Check the resolution of the entry to be sure
> v3->v4: Optimize the register reference; add a module option

For the series:

Reviewed-by: Adam Jackson <ajax@redhat.com>

- ajax

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