[Intel-gfx] [PATCH] drm/i915: Parsing VBT if size of VBT exceeds 6KB

[Chris Wilson]

On Mon, Dec 14, 2015 at 05:46:41PM +0530, Deepak M wrote:
> Currently the iomap for VBT works only if the size of the
> VBT is less than 6KB, but if the size of the VBT exceeds
> 6KB than the physical address and the size of the VBT to
> be iomapped is specified in the mailbox3 and is iomapped
> accordingly.
> 
> v3: -Splitted the patch into small ones
>     -Handeled memory unmap in intel_opregion_fini
>     -removed the new file created for opregion macro`s
> v4: Moving the vbt assignment after the opregion fields are assigned
> 
> Cc: Mika Kahola <mika.kahola at intel.com>
> Cc: Jani Nikula <jani.nikula at intel.com>
> Signed-off-by: Deepak M <m.deepak at intel.com>
> ---
> 
>  drivers/gpu/drm/i915/intel_opregion.c | 47 +++++++++++++++++++++++++----------
>  1 file changed, 34 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_opregion.c b/drivers/gpu/drm/i915/intel_opregion.c
> index 7908a1d..5116690 100644
> --- a/drivers/gpu/drm/i915/intel_opregion.c
> +++ b/drivers/gpu/drm/i915/intel_opregion.c
> @@ -856,6 +856,8 @@ void intel_opregion_fini(struct drm_device *dev)
>  	}
>  
>  	/* just clear all opregion memory pointers now */
> +	if (opregion->header->opregion_ver >= 2 && opregion->asle->rvda)
> +		memunmap(opregion->vbt);
>  	memunmap(opregion->header);
>  	opregion->header = NULL;
>  	opregion->acpi = NULL;
> @@ -933,7 +935,8 @@ int intel_opregion_setup(struct drm_device *dev)
>  	char buf[sizeof(OPREGION_SIGNATURE)];
>  	const struct vbt_header *vbt = NULL;
>  	int err = 0;
> -	void *base;
> +	void *base, *vbt_base;
> +	size_t size;
>  
>  	BUILD_BUG_ON(sizeof(struct opregion_header) != 0x100);
>  	BUILD_BUG_ON(sizeof(struct opregion_acpi) != 0x100);
> @@ -963,19 +966,7 @@ int intel_opregion_setup(struct drm_device *dev)
>  		goto err_out;
>  	}
>  
> -	vbt = validate_vbt(base + OPREGION_VBT_OFFSET,
> -				MAILBOX_4_SIZE, "OpRegion");
> -
> -	if (vbt == NULL) {
> -		err = -EINVAL;
> -		goto err_out;
> -	}
> -
> -	vbt = (const struct vbt_header *)(base + OPREGION_VBT_OFFSET);
> -	dev_priv->opregion.vbt_size = vbt->vbt_size;
> -
>  	opregion->header = base;
> -	opregion->vbt = base + OPREGION_VBT_OFFSET;
>  
>  	opregion->lid_state = base + ACPI_CLID;
>  	opregion->asle_ext = base + OPREGION_ASLE_EXT_OFFSET;
> @@ -998,6 +989,36 @@ int intel_opregion_setup(struct drm_device *dev)
>  		opregion->asle->ardy = ASLE_ARDY_NOT_READY;
>  	}
>  
> +	/*
> +	 * Non-zero value in rvda field is an indication to driver that a
> +	 * valid Raw VBT is stored in that address and driver should not refer
> +	 * to mailbox4 for getting VBT.
> +	 */
> +	if (opregion->header->opregion_ver >= 2 && opregion->asle->rvda) {
> +		size = opregion->asle->rvds;
> +		vbt_base = memremap(opregion->asle->rvda,
> +				size, MEMREMAP_WB);
> +	} else {
> +		size = MAILBOX_4_SIZE;
> +		vbt_base = base + OPREGION_VBT_OFFSET;
> +	}
> +
> +	vbt = validate_vbt(vbt_base, size, "OpRegion");
> +
> +	if (vbt == NULL) {
> +		err = -EINVAL;
> +		goto err_out;
> +	}
> +
> +	/* Assigning the vbt_size based on the VBT location */
> +	if (opregion->header->opregion_ver >= 2 && opregion->asle->rvda)
> +		dev_priv->opregion.vbt_size = opregion->asle->rvds;
> +	else {
> +		vbt = (const struct vbt_header *)(base + OPREGION_VBT_OFFSET);
i.e. vbt = vbt_base;

which is already done by vbt = validate_vbt;

> +		dev_priv->opregion.vbt_size = vbt->vbt_size;
> +	}

So this reduces down to:

/* Explanation why the new method cannot store the size in vbt->vbt_size */
if (vbt != opregion->asle->rvda)
	size = vbt->vbt_size;
dev_priv->opregion.vbt_size = size;
opregrion->vbt = vbt;

And the vbt_base variable is redundant.

Cut out the tautology and reduce the apparent complex
interdependence between paths.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre