Re: [PATCH] drm/i915/kbl: Fix DMC load on Kabylake.

[Jani Nikula <jani.nikula@linux.intel.com>]

On Wed, 09 Dec 2015, Rodrigo Vivi <rodrigo.vivi@intel.com> wrote:
> Kabylake A0 is based on Skylake H0.
>
> v2: Don't assume revid+7 and only load the one we are sure about.
>
> v3: Rebase on top of latest changes.
>
> Cc: Imre Deak <imre.deak@intel.com>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_csr.c | 18 +++++++++++++++---
>  1 file changed, 15 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_csr.c b/drivers/gpu/drm/i915/intel_csr.c
> index 6c6a669..7e5ce66 100644
> --- a/drivers/gpu/drm/i915/intel_csr.c
> +++ b/drivers/gpu/drm/i915/intel_csr.c
> @@ -181,8 +181,20 @@ static const struct stepping_info *intel_get_stepping_info(struct drm_device *de
>  {
>  	const struct stepping_info *si;
>  	unsigned int size;
> +	int revid = INTEL_REVID(dev);
>  
> -	if (IS_SKYLAKE(dev)) {
> +	/*
> +	 * FIXME: Kabylake derivated from Skylake H0, so SKL H0
> +	 * is the right firmware for KBL A0 (revid 0).
> +	 * We have no visibility yet how next KBL steppings will
> +	 * be handled by firmware, so let's just load one we know
> +	 * it works on the KBLs we have so far add support for
> +	 * the only current available KBL.
> +	 */

Really I'd just add 

static const struct stepping_info kbl_stepping_info[] = {
	{'H', '0'}, {'I', '0'}
};

with your comment above and an if (IS_KABYLAKE()) branch picking the
right array, and keep this function nice and void of special casing and
magic 7.

BR,
Jani.



> +	if (IS_KABYLAKE(dev))
> +		revid = 7;
> +
> +	if (IS_SKYLAKE(dev) || IS_KABYLAKE(dev)) {
>  		size = ARRAY_SIZE(skl_stepping_info);
>  		si = skl_stepping_info;
>  	} else if (IS_BROXTON(dev)) {
> @@ -192,8 +204,8 @@ static const struct stepping_info *intel_get_stepping_info(struct drm_device *de
>  		return NULL;
>  	}
>  
> -	if (INTEL_REVID(dev) < size)
> -		return si + INTEL_REVID(dev);
> +	if (revid < size)
> +		return si + revid;
>  
>  	return NULL;
>  }

-- 
Jani Nikula, Intel Open Source Technology Center
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