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

["Thulasimani, Sivakumar" <sivakumar.thulasimani@intel.com>]

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.

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);
>   }
>   

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