[Intel-gfx] [PATCH] [intel-gfx] drm/i915/intel_csr.c Fix DMC FW Loading issue on ICL.

[Imre Deak]

On Tue, Aug 28, 2018 at 10:44:56AM -0400, Jyoti Yadav wrote:
> From: Jyoti <jyoti.r.yadav at intel.com>
> 
> This patch resolves the DMC FW loading issue.
> Earlier DMC FW package have only one DMC FW for one stepping. But as such
> there is no such restriction from Package side.
> For ICL icl_dmc_ver1_07.bin binary package has DMC FW for 2 steppings.
> So while reading the dmc_offset from package header, for 1st stepping offset
> used to come 0x0 and was working fine till now.
> But for second stepping and other steppings, offset is non zero numaber and is
> in dwords. So we need to convert into bytes to fetch correct DMC FW from
> correct place.
> 
> Also there is no such restriction on DMC FW size. So removing that check also.
> ---
>  drivers/gpu/drm/i915/intel_csr.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_csr.c b/drivers/gpu/drm/i915/intel_csr.c
> index 1ec4f09..4590796 100644
> --- a/drivers/gpu/drm/i915/intel_csr.c
> +++ b/drivers/gpu/drm/i915/intel_csr.c
> @@ -359,6 +359,8 @@ static uint32_t *parse_csr_fw(struct drm_i915_private *dev_priv,
>  			  si->stepping);
>  		return NULL;
>  	}
> +	/* Convert dmc_offset into number of bytes. By default it is in dwords*/
> +	dmc_offset *= 4;

Yes, this looks correct based on the latest ICL binary. Not sure if
we ever had a binary with multiple FWs in it. BSpec says about this
offset:

"FW offset within the package"

while for other length fields it states explicitly if they are in
dwords. So this would need to be clarified in BSpec, could you file a
request for update there?

>  	readcount += dmc_offset;
>  
>  	/* Extract dmc_header information. */
> @@ -391,10 +393,6 @@ static uint32_t *parse_csr_fw(struct drm_i915_private *dev_priv,
>  
>  	/* fw_size is in dwords, so multiplied by 4 to convert into bytes. */
>  	nbytes = dmc_header->fw_size * 4;
> -	if (nbytes > CSR_MAX_FW_SIZE) {
> -		DRM_ERROR("DMC firmware too big (%u bytes)\n", nbytes);
> -		return NULL;
> -	}

There is a maximum size defined, we just didn't update it past GEN9:

GLK, CNL: 0x3FFF
GEN11+  : 0x5FFF

could you please update the check accordingly?

>  	csr->dmc_fw_size = dmc_header->fw_size;
>  
>  	dmc_payload = kmalloc(nbytes, GFP_KERNEL);
> -- 
> 1.9.1
>