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

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

On Wed, Feb 03, 2016 at 04:49:07PM -0800, 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.
> 
> Signed-off-by: Bob Paauwe <bob.j.paauwe@intel.com>
> [mattrope: Expand commit message]
> Signed-off-by: Matt Roper <matthew.d.roper@intel.com>

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=93915

> ---
>  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);
>  }
>  
> -- 
> 2.1.4
> 

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