Re: [PATCH v4 3/7] drm/i915/guc: add enable_guc_loading parameter

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 13/05/16 15:36, Dave Gordon wrote:
> Split the function of "enable_guc_submission" into two separate
> options.  The new one ("enable_guc_loading") controls only the
> *fetching and loading* of the GuC firmware image. The existing
> one is redefined to control only the *use* of the GuC for batch
> submission once the firmware is loaded.
>
> In addition, the degree of control has been refined from a simple
> bool to an integer key, allowing several options:
> -1 (default)     whatever the platform default is
>   0  DISABLE      don't load/use the GuC
>   1  BEST EFFORT  try to load/use the GuC, fallback if not available
>   2  REQUIRE      must load/use the GuC, else leave the GPU wedged
>
> The new platform default (as coded here) will be to attempt to
> load the GuC iff the device has a GuC that requires firmware,
> but not yet to use it for submission. A later patch will change
> to enable it if appropriate.
>
> v4:
>      Changed some error-message levels, mostly ERROR->INFO, per
>      review comments by Tvrtko Ursulin.
>
> Signed-off-by: Dave Gordon <david.s.gordon@intel.com>
> ---
>   drivers/gpu/drm/i915/i915_gem.c            |   1 -
>   drivers/gpu/drm/i915/i915_guc_submission.c |   4 +-
>   drivers/gpu/drm/i915/i915_params.c         |  14 +++-
>   drivers/gpu/drm/i915/i915_params.h         |   3 +-
>   drivers/gpu/drm/i915/intel_guc_loader.c    | 108 ++++++++++++++++-------------
>   5 files changed, 76 insertions(+), 54 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 2a7be71..2bf8743 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -4870,7 +4870,6 @@ int i915_gem_init_engines(struct drm_device *dev)
>   		ret = intel_guc_setup(dev);
>   		if (ret) {
>   			DRM_ERROR("Failed to initialize GuC, error %d\n", ret);

This error msg should go as well I think.

> -			ret = -EIO;
>   			goto out;
>   		}
>   	}
> diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c
> index 169242a..916cd67 100644
> --- a/drivers/gpu/drm/i915/i915_guc_submission.c
> +++ b/drivers/gpu/drm/i915/i915_guc_submission.c
> @@ -969,7 +969,7 @@ int intel_guc_suspend(struct drm_device *dev)
>   	struct intel_context *ctx;
>   	u32 data[3];
>
> -	if (!i915.enable_guc_submission)
> +	if (guc->guc_fw.guc_fw_load_status != GUC_FIRMWARE_SUCCESS)
>   		return 0;
>
>   	ctx = dev_priv->kernel_context;
> @@ -995,7 +995,7 @@ int intel_guc_resume(struct drm_device *dev)
>   	struct intel_context *ctx;
>   	u32 data[3];
>
> -	if (!i915.enable_guc_submission)
> +	if (guc->guc_fw.guc_fw_load_status != GUC_FIRMWARE_SUCCESS)
>   		return 0;

Will the above two do the right thing for the fw_path == NULL case? That 
is !HAS_GUC_UCODE && HAS_GUC_SCHED? Looks like load status will bt NONE 
in that case, GuC submission will be enabled and suspend and resume 
hooks will be skipped?

Maybe fetch and load status should be set to success on such platforms?

>
>   	ctx = dev_priv->kernel_context;
> diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
> index 383c076..6a5578c 100644
> --- a/drivers/gpu/drm/i915/i915_params.c
> +++ b/drivers/gpu/drm/i915/i915_params.c
> @@ -54,7 +54,8 @@ struct i915_params i915 __read_mostly = {
>   	.verbose_state_checks = 1,
>   	.nuclear_pageflip = 0,
>   	.edp_vswing = 0,
> -	.enable_guc_submission = false,
> +	.enable_guc_loading = -1,
> +	.enable_guc_submission = 0,
>   	.guc_log_level = -1,
>   	.enable_dp_mst = true,
>   	.inject_load_failure = 0,
> @@ -198,8 +199,15 @@ struct i915_params i915 __read_mostly = {
>   		 "(0=use value from vbt [default], 1=low power swing(200mV),"
>   		 "2=default swing(400mV))");
>
> -module_param_named_unsafe(enable_guc_submission, i915.enable_guc_submission, bool, 0400);
> -MODULE_PARM_DESC(enable_guc_submission, "Enable GuC submission (default:false)");
> +module_param_named_unsafe(enable_guc_loading, i915.enable_guc_loading, int, 0400);
> +MODULE_PARM_DESC(enable_guc_loading,
> +		"Enable GuC firmware loading "
> +		"(-1=auto [default], 0=never, 1=if available, 2=required)");
> +
> +module_param_named_unsafe(enable_guc_submission, i915.enable_guc_submission, int, 0400);
> +MODULE_PARM_DESC(enable_guc_submission,
> +		"Enable GuC submission "
> +		"(-1=auto, 0=never [default], 1=if available, 2=required)");
>
>   module_param_named(guc_log_level, i915.guc_log_level, int, 0400);
>   MODULE_PARM_DESC(guc_log_level,
> diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
> index 65e73dd..1323261 100644
> --- a/drivers/gpu/drm/i915/i915_params.h
> +++ b/drivers/gpu/drm/i915/i915_params.h
> @@ -45,6 +45,8 @@ struct i915_params {
>   	int enable_ips;
>   	int invert_brightness;
>   	int enable_cmd_parser;
> +	int enable_guc_loading;
> +	int enable_guc_submission;
>   	int guc_log_level;
>   	int use_mmio_flip;
>   	int mmio_debug;
> @@ -57,7 +59,6 @@ struct i915_params {
>   	bool load_detect_test;
>   	bool reset;
>   	bool disable_display;
> -	bool enable_guc_submission;
>   	bool verbose_state_checks;
>   	bool nuclear_pageflip;
>   	bool enable_dp_mst;
> diff --git a/drivers/gpu/drm/i915/intel_guc_loader.c b/drivers/gpu/drm/i915/intel_guc_loader.c
> index b14a3a3..3d33944 100644
> --- a/drivers/gpu/drm/i915/intel_guc_loader.c
> +++ b/drivers/gpu/drm/i915/intel_guc_loader.c
> @@ -391,49 +391,37 @@ int intel_guc_setup(struct drm_device *dev)
>   {
>   	struct drm_i915_private *dev_priv = dev->dev_private;
>   	struct intel_guc_fw *guc_fw = &dev_priv->guc.guc_fw;
> -	int retries, err = 0;
> +	const char *fw_path = guc_fw->guc_fw_path;
> +	int retries, ret, err = 0;
>
> -	if (!i915.enable_guc_submission)
> -		return 0;
> -
> -	DRM_DEBUG_DRIVER("GuC fw status: fetch %s, load %s\n",
> +	DRM_DEBUG_DRIVER("GuC fw status: path %s, fetch %s, load %s\n",
> +		fw_path,
>   		intel_guc_fw_status_repr(guc_fw->guc_fw_fetch_status),
>   		intel_guc_fw_status_repr(guc_fw->guc_fw_load_status));
>
> -	direct_interrupts_to_host(dev_priv);
> +	/* Loading forbidden, or no firmware to load? */
> +	if (!i915.enable_guc_loading)
> +		goto fail;
> +	if (fw_path == NULL)
> +		goto fail;
> +	if (*fw_path == '\0') {
> +		DRM_INFO("No GuC firmware known for this platform\n");
> +		goto fail;
> +	}
>
> -	if (guc_fw->guc_fw_fetch_status == GUC_FIRMWARE_NONE)
> -		return 0;
> +	/* Fetch failed, or already fetched but failed to load? */
> +	if (guc_fw->guc_fw_fetch_status != GUC_FIRMWARE_SUCCESS)
> +		goto fail;
> +	if (guc_fw->guc_fw_load_status == GUC_FIRMWARE_FAIL)
> +		goto fail;
>
> -	if (guc_fw->guc_fw_fetch_status == GUC_FIRMWARE_SUCCESS &&
> -	    guc_fw->guc_fw_load_status == GUC_FIRMWARE_FAIL)
> -		return -ENOEXEC;
> +	direct_interrupts_to_host(dev_priv);
>
>   	guc_fw->guc_fw_load_status = GUC_FIRMWARE_PENDING;
>
> -	DRM_DEBUG_DRIVER("GuC fw fetch status %s\n",
> -		intel_guc_fw_status_repr(guc_fw->guc_fw_fetch_status));
> -
> -	switch (guc_fw->guc_fw_fetch_status) {
> -	case GUC_FIRMWARE_FAIL:
> -		/* something went wrong :( */
> -		err = -EIO;
> -		goto fail;
> -
> -	case GUC_FIRMWARE_NONE:
> -	case GUC_FIRMWARE_PENDING:
> -	default:
> -		/* "can't happen" */
> -		WARN_ONCE(1, "GuC fw %s invalid guc_fw_fetch_status %s [%d]\n",
> -			guc_fw->guc_fw_path,
> -			intel_guc_fw_status_repr(guc_fw->guc_fw_fetch_status),
> -			guc_fw->guc_fw_fetch_status);
> -		err = -ENXIO;
> -		goto fail;
> -
> -	case GUC_FIRMWARE_SUCCESS:
> -		break;
> -	}
> +	DRM_DEBUG_DRIVER("GuC fw status: fetch %s, load %s\n",
> +		intel_guc_fw_status_repr(guc_fw->guc_fw_fetch_status),
> +		intel_guc_fw_status_repr(guc_fw->guc_fw_load_status));
>
>   	err = i915_guc_submission_init(dev);
>   	if (err)
> @@ -486,7 +474,6 @@ int intel_guc_setup(struct drm_device *dev)
>   	return 0;
>
>   fail:
> -	DRM_ERROR("GuC firmware load failed, err %d\n", err);
>   	if (guc_fw->guc_fw_load_status == GUC_FIRMWARE_PENDING)
>   		guc_fw->guc_fw_load_status = GUC_FIRMWARE_FAIL;
>
> @@ -494,7 +481,36 @@ int intel_guc_setup(struct drm_device *dev)
>   	i915_guc_submission_disable(dev);
>   	i915_guc_submission_fini(dev);
>
> -	return err;
> +	/*
> +	 * We've failed to load the firmware :(
> +	 *
> +	 * Decide whether to disable GuC submission and fall back to
> +	 * execlist mode, and whether to hide the error by returning
> +	 * zero or to return -EIO, which the caller will treat as a
> +	 * nonfatal error (i.e. it doesn't prevent driver load, but
> +	 * marks the GPU as wedged until reset).
> +	 */
> +	if (i915.enable_guc_loading > 1) {
> +		ret = -EIO;
> +	} else if (HAS_GUC_SCHED(dev) && !HAS_GUC_UCODE(dev)) {
> +		/* This GuC works even without firmware :) */
> +		return 0;
> +	} else if (i915.enable_guc_submission > 1) {
> +		ret = -EIO;
> +	} else {
> +		ret = 0;
> +	}
> +
> +	if (ret == -EIO)
> +		DRM_ERROR("GuC firmware load failed, err %d\n", err);
> +	else
> +		DRM_INFO("GuC firmware load failed, err %d\n", err);
> +
> +	if (i915.enable_guc_submission)
> +		DRM_INFO("falling back to execlist mode, ret %d\n", ret);

ret is always zero in this msg?

> +	i915.enable_guc_submission = 0;
> +
> +	return ret;
>   }
>
>   static void guc_fw_fetch(struct drm_device *dev, struct intel_guc_fw *guc_fw)
> @@ -635,8 +651,11 @@ void intel_guc_init(struct drm_device *dev)
>   	struct intel_guc_fw *guc_fw = &dev_priv->guc.guc_fw;
>   	const char *fw_path;
>
> -	if (!HAS_GUC_SCHED(dev))
> -		i915.enable_guc_submission = false;
> +	/* A negative value means "use platform default" */
> +	if (i915.enable_guc_loading < 0)
> +		i915.enable_guc_loading = HAS_GUC_UCODE(dev);
> +	if (i915.enable_guc_submission < 0)
> +		i915.enable_guc_submission = HAS_GUC_SCHED(dev);
>
>   	if (!HAS_GUC_UCODE(dev)) {
>   		fw_path = NULL;
> @@ -649,26 +668,21 @@ void intel_guc_init(struct drm_device *dev)
>   		guc_fw->guc_fw_major_wanted = 8;
>   		guc_fw->guc_fw_minor_wanted = 7;
>   	} else {
> -		i915.enable_guc_submission = false;
>   		fw_path = "";	/* unknown device */
>   	}
>
> -	if (!i915.enable_guc_submission)
> -		return;
> -
>   	guc_fw->guc_dev = dev;
>   	guc_fw->guc_fw_path = fw_path;
>   	guc_fw->guc_fw_fetch_status = GUC_FIRMWARE_NONE;
>   	guc_fw->guc_fw_load_status = GUC_FIRMWARE_NONE;
>
> +	/* Early (and silent) return if GuC loading is disabled */
> +	if (!i915.enable_guc_loading)
> +		return;
>   	if (fw_path == NULL)
>   		return;
> -
> -	if (*fw_path == '\0') {
> -		DRM_ERROR("No GuC firmware known for this platform\n");
> -		guc_fw->guc_fw_fetch_status = GUC_FIRMWARE_FAIL;
> +	if (*fw_path == '\0')
>   		return;
> -	}
>
>   	guc_fw->guc_fw_fetch_status = GUC_FIRMWARE_PENDING;
>   	DRM_DEBUG_DRIVER("GuC firmware pending, path %s\n", fw_path);
>

Regards,

Tvrtko
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