[Intel-gfx] [PATCH 16/16] drm/i915: Preserve VGACNTR bits from the BIOS

[Thomas Richter]

On 15.08.2014 00:22, ville.syrjala at linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
>
> My Fujistsu-Siemens Lifebook S6010 doesn't like to resume from
> S3 unless VGACNTR has been restore to the original value. The BIOS
> value in this case was 0x0124008E. Setting the "VGA disable" bit
> doesn't interfere with the S3 resume fortunately.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

Works on the S6010 as advertized, though cannot test on the R31 since it
does not resume from S3 - it does not even reach the real-mode entry 
hook of the kernel.

Tested-by: Thomas Richter <richter at rus.uni-stuttgart.de>

> ---
>   drivers/gpu/drm/i915/i915_drv.h      | 2 ++
>   drivers/gpu/drm/i915/intel_display.c | 8 +++++++-
>   2 files changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index b1ed71e..e0f64e4 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1638,6 +1638,8 @@ struct drm_i915_private {
>   	 */
>   	struct workqueue_struct *dp_wq;
>
> +	uint32_t bios_vgacntr;
> +
>   	/* Old dri1 support infrastructure, beware the dragons ya fools entering
>   	 * here! */
>   	struct i915_dri1_state dri1;
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 92baf6f..f154993 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -12591,7 +12591,11 @@ static void i915_disable_vga(struct drm_device *dev)
>   	vga_put(dev->pdev, VGA_RSRC_LEGACY_IO);
>   	udelay(300);
>
> -	I915_WRITE(vga_reg, VGA_DISP_DISABLE);
> +	/*
> +	 * Fujitsu-Siemens Lifebook S6010 (830) has problems resuming
> +	 * from S3 without preserving (some of?) the other bits.
> +	 */
> +	I915_WRITE(vga_reg, dev_priv->bios_vgacntr | VGA_DISP_DISABLE);
>   	POSTING_READ(vga_reg);
>   }
>
> @@ -12680,6 +12684,8 @@ void intel_modeset_init(struct drm_device *dev)
>
>   	intel_shared_dpll_init(dev);
>
> +	/* save the BIOS value before clobbering it */
> +	dev_priv->bios_vgacntr = I915_READ(i915_vgacntrl_reg(dev));
>   	/* Just disable it once at startup */
>   	i915_disable_vga(dev);
>   	intel_setup_outputs(dev);
>