Re: [PATCH] drm/i915/bxt: Save/restore HOTPLUG_CTL during suspend/resume.

[Matt Roper <matthew.d.roper@intel.com>]

On Thu, Feb 04, 2016 at 07:17:08AM +0530, Thulasimani, Sivakumar wrote:
> 
> 
> On 2/4/2016 6:19 AM, Matt Roper wrote:
> >From: Bob Paauwe <bob.j.paauwe@intel.com>
> >
> >Broxton has some additional bits in the HOTPLUG_CTL register that
> >indicate whether the HPD sense lines need to be inverted or not for the
> >current platform.  The BIOS sets these bits to an appropriate value at
> >boot time, but the value is lost across suspend/resume.  We need to save
> >and restore the register so that hotplug and display detect works on
> >resume.
> i have a patch that is about to be upstreamed that will read and write these
> values based on vbt. Shuhangi did the basic testing last week so will
> ask her to send to mail list today.  i would prefer that patch where
> we know how and when to set these bits rather than just save
> & restore.

Sure, sounds good.  Can your patch handle cases where there is no VBT by
falling back to a save/restore?  Quite often in the embedded world, we
have very specialized boot firmware that doesn't resemble vbios/gop and
doesn't have any VBT info.


Matt

> 
> regards,
> Sivakumar
> >Signed-off-by: Bob Paauwe <bob.j.paauwe@intel.com>
> >[mattrope: Expand commit message]
> >Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
> >---
> >  drivers/gpu/drm/i915/i915_drv.h     | 1 +
> >  drivers/gpu/drm/i915/i915_suspend.c | 7 +++++++
> >  2 files changed, 8 insertions(+)
> >
> >diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> >index 77227a3..2278117 100644
> >--- a/drivers/gpu/drm/i915/i915_drv.h
> >+++ b/drivers/gpu/drm/i915/i915_drv.h
> >@@ -1061,6 +1061,7 @@ struct i915_suspend_saved_registers {
> >  	uint64_t saveFENCE[I915_MAX_NUM_FENCES];
> >  	u32 savePCH_PORT_HOTPLUG;
> >  	u16 saveGCDGMBUS;
> >+	u32 saveHOTPLUG;
> >  };
> >  struct vlv_s0ix_state {
> >diff --git a/drivers/gpu/drm/i915/i915_suspend.c b/drivers/gpu/drm/i915/i915_suspend.c
> >index 34e061a..efe1e77 100644
> >--- a/drivers/gpu/drm/i915/i915_suspend.c
> >+++ b/drivers/gpu/drm/i915/i915_suspend.c
> >@@ -59,6 +59,10 @@ static void i915_save_display(struct drm_device *dev)
> >  	/* save FBC interval */
> >  	if (HAS_FBC(dev) && INTEL_INFO(dev)->gen <= 4 && !IS_G4X(dev))
> >  		dev_priv->regfile.saveFBC_CONTROL = I915_READ(FBC_CONTROL);
> >+
> >+	if (IS_BROXTON(dev))
> >+		dev_priv->regfile.saveHOTPLUG = I915_READ(PCH_PORT_HOTPLUG);
> >+
> >  }
> >  static void i915_restore_display(struct drm_device *dev)
> >@@ -98,6 +102,9 @@ static void i915_restore_display(struct drm_device *dev)
> >  	if (HAS_FBC(dev) && INTEL_INFO(dev)->gen <= 4 && !IS_G4X(dev))
> >  		I915_WRITE(FBC_CONTROL, dev_priv->regfile.saveFBC_CONTROL);
> >+	if (IS_BROXTON(dev))
> >+		I915_WRITE(PCH_PORT_HOTPLUG, dev_priv->regfile.saveHOTPLUG);
> >+
> >  	i915_redisable_vga(dev);
> >  }
> 

-- 
Matt Roper
Graphics Software Engineer
IoTG Platform Enabling & Development
Intel Corporation
(916) 356-2795
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