[Intel-gfx] [PATCH 01/15] drm/i915/guc: Add support for data reporting in GuC responses

[Michel Thierry]

On 8/4/2017 9:26 AM, Michal Wajdeczko wrote:
> GuC may return additional data in the command status response.
> Format and meaning of this data is action specific.
> We will use this non-negative data as a new success return value.
> 
> Signed-off-by: Michal Wajdeczko <michal.wajdeczko at intel.com>
> Cc: Oscar Mateo <oscar.mateo at intel.com>
> Cc: Michel Thierry <michel.thierry at intel.com>
> Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
> ---
>   drivers/gpu/drm/i915/intel_guc_ct.c   | 14 +++++++-------
>   drivers/gpu/drm/i915/intel_guc_fwif.h |  6 ++++++
>   drivers/gpu/drm/i915/intel_uc.c       |  5 ++++-
>   3 files changed, 17 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_guc_ct.c b/drivers/gpu/drm/i915/intel_guc_ct.c
> index c4cbec1..1249868 100644
> --- a/drivers/gpu/drm/i915/intel_guc_ct.c
> +++ b/drivers/gpu/drm/i915/intel_guc_ct.c
> @@ -387,9 +387,9 @@ static int ctch_send(struct intel_guc *guc,
>   	err = wait_for_response(desc, fence, status);
>   	if (unlikely(err))
>   		return err;
> -	if (*status != INTEL_GUC_STATUS_SUCCESS)
> +	if (INTEL_GUC_RECV_TO_STATUS(*status) != INTEL_GUC_STATUS_SUCCESS)
>   		return -EIO;
> -	return 0;
> +	return INTEL_GUC_RECV_TO_DATA(*status);
>   }
>   
>   /*
> @@ -399,18 +399,18 @@ static int intel_guc_send_ct(struct intel_guc *guc, const u32 *action, u32 len)
>   {
>   	struct intel_guc_ct_channel *ctch = &guc->ct.host_channel;
>   	u32 status = ~0; /* undefined */
> -	int err;
> +	int ret;
>   
>   	mutex_lock(&guc->send_mutex);
>   
> -	err = ctch_send(guc, ctch, action, len, &status);
> -	if (unlikely(err)) {
> +	ret = ctch_send(guc, ctch, action, len, &status);
> +	if (unlikely(ret < 0)) {
>   		DRM_ERROR("CT: send action %#X failed; err=%d status=%#X\n",
> -			  action[0], err, status);
> +			  action[0], ret, status);
>   	}
>   
>   	mutex_unlock(&guc->send_mutex);
> -	return err;
> +	return ret;
>   }
>   
>   /**
> diff --git a/drivers/gpu/drm/i915/intel_guc_fwif.h b/drivers/gpu/drm/i915/intel_guc_fwif.h
> index 5fa2860..98c0560 100644
> --- a/drivers/gpu/drm/i915/intel_guc_fwif.h
> +++ b/drivers/gpu/drm/i915/intel_guc_fwif.h
> @@ -567,10 +567,16 @@ enum intel_guc_action {
>    * command in SS0. The response is distinguishable from a command
>    * by the fact that all the MASK bits are set. The remaining bits
>    * give more detail.
> + * Bits [16:27] are reserved for optional data reporting.
>    */
>   #define	INTEL_GUC_RECV_MASK	((u32)0xF0000000)
>   #define	INTEL_GUC_RECV_IS_RESPONSE(x)	((u32)(x) >= INTEL_GUC_RECV_MASK)
>   #define	INTEL_GUC_RECV_STATUS(x)	(INTEL_GUC_RECV_MASK | (x))
> +#define INTEL_GUC_RECV_DATA_SHIFT	16
> +#define INTEL_GUC_RECV_DATA_MASK	(0xFFF << INTEL_GUC_RECV_DATA_SHIFT)
> +#define INTEL_GUC_RECV_TO_STATUS(x)	((x) & ~ INTEL_GUC_RECV_DATA_MASK)

checkpatch should have complained about the blank space after '~'.

> +#define INTEL_GUC_RECV_TO_DATA(x)	(((x) & INTEL_GUC_RECV_DATA_MASK) >> \
> +					 INTEL_GUC_RECV_DATA_SHIFT)
>   
>   /* GUC will return status back to SOFT_SCRATCH_O_REG */
>   enum intel_guc_status {
> diff --git a/drivers/gpu/drm/i915/intel_uc.c b/drivers/gpu/drm/i915/intel_uc.c
> index 27e072c..ff25477 100644
> --- a/drivers/gpu/drm/i915/intel_uc.c
> +++ b/drivers/gpu/drm/i915/intel_uc.c
> @@ -502,7 +502,7 @@ int intel_guc_send_mmio(struct intel_guc *guc, const u32 *action, u32 len)
>   					   INTEL_GUC_RECV_MASK,
>   					   INTEL_GUC_RECV_MASK,
>   					   10, 10, &status);
> -	if (status != INTEL_GUC_STATUS_SUCCESS) {
> +	if (INTEL_GUC_RECV_TO_STATUS(status) != INTEL_GUC_STATUS_SUCCESS) {
>   		/*
>   		 * Either the GuC explicitly returned an error (which
>   		 * we convert to -EIO here) or no response at all was
> @@ -514,6 +514,9 @@ int intel_guc_send_mmio(struct intel_guc *guc, const u32 *action, u32 len)
>   		DRM_WARN("INTEL_GUC_SEND: Action 0x%X failed;"
>   			 " ret=%d status=0x%08X response=0x%08X\n",
>   			 action[0], ret, status, I915_READ(SOFT_SCRATCH(15)));
> +	} else {
> +		/* Use data encoded in status dword as return value */
> +		ret = INTEL_GUC_RECV_TO_DATA(status);
>   	}
>   
>   	intel_uncore_forcewake_put(dev_priv, guc->send_regs.fw_domains);
> 

Other than the blank space after that '~', it looks good to me.

Just a note, for other people reading this; there are 3 cases in which 
intel_guc_send return value is only checked for truthiness (i.e. 
__guc_allocate_doorbell, __guc_deallocate_doorbell and 
intel_guc_sample_forcewake callers are checking for 'if (err)').

I know none of the existing H2G commands will return any extra data, so 
intel_guc_send should be returning only negative numbers or zero (for now).

-Michel