Re: [PATCH] drm/i915: add enable_guc_loading parameter

[Yu Dai <yu.dai@intel.com>]

LGTM.

Reviewed-by: Alex Dai <yu.dai@intel.com>

Thanks,
Alex

On 02/03/2016 04:56 AM, 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, to attempt to
> use it iff the device has a GuC that supports the submission protocol
> (with or without firmware), and to fall back to execlist mode if any
> required firmware cannot be found or fails to load.
>
> Signed-off-by: Dave Gordon <david.s.gordon@intel.com>
> Cc: Jani Nikula <jani.nikula@linux.intel.com>
> ---
>   drivers/gpu/drm/i915/i915_gem.c         |  1 -
>   drivers/gpu/drm/i915/i915_params.c      | 14 ++++-
>   drivers/gpu/drm/i915/i915_params.h      |  3 +-
>   drivers/gpu/drm/i915/intel_guc_loader.c | 99 ++++++++++++++++++---------------
>   4 files changed, 68 insertions(+), 49 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index a928823..cd7aada 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -4892,7 +4892,6 @@ int i915_gem_init_rings(struct drm_device *dev)
>   		ret = intel_guc_ucode_load(dev);
>   		if (ret) {
>   			DRM_ERROR("Failed to initialize GuC, error %d\n", ret);
> -			ret = -EIO;
>   			goto out;
>   		}
>   	}
> diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
> index 8b9f368..ad785ad 100644
> --- a/drivers/gpu/drm/i915/i915_params.c
> +++ b/drivers/gpu/drm/i915/i915_params.c
> @@ -55,7 +55,8 @@ 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 = -1,
>   	.guc_log_level = -1,
>   };
>   
> @@ -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_submission,
> +		"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 [default], 0=never, 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 5299290..7180261 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 reset;
>   	bool disable_display;
>   	bool disable_vtd_wa;
> -	bool enable_guc_submission;
>   	bool verbose_state_checks;
>   	bool nuclear_pageflip;
>   };
> diff --git a/drivers/gpu/drm/i915/intel_guc_loader.c b/drivers/gpu/drm/i915/intel_guc_loader.c
> index 3accd91..e7eb3db 100644
> --- a/drivers/gpu/drm/i915/intel_guc_loader.c
> +++ b/drivers/gpu/drm/i915/intel_guc_loader.c
> @@ -369,49 +369,37 @@ int intel_guc_ucode_load(struct drm_device *dev)
>   {
>   	struct drm_i915_private *dev_priv = dev->dev_private;
>   	struct intel_guc_fw *guc_fw = &dev_priv->guc.guc_fw;
> +	const char *fw_path = guc_fw->guc_fw_path;
>   	int 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_ERROR("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)
> @@ -440,6 +428,8 @@ int intel_guc_ucode_load(struct drm_device *dev)
>   	return 0;
>   
>   fail:
> +	DRM_DEBUG_DRIVER("GuC firmware load fail, err %d\n", err);
> +
>   	if (guc_fw->guc_fw_load_status == GUC_FIRMWARE_PENDING)
>   		guc_fw->guc_fw_load_status = GUC_FIRMWARE_FAIL;
>   
> @@ -447,6 +437,29 @@ int intel_guc_ucode_load(struct drm_device *dev)
>   	i915_guc_submission_disable(dev);
>   	i915_guc_submission_fini(dev);
>   
> +	/*
> +	 * 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) {
> +		err = -EIO;
> +	} else if (HAS_GUC_SCHED(dev) && !HAS_GUC_UCODE(dev)) {
> +		return 0;
> +	} else if (i915.enable_guc_submission > 1) {
> +		err = -EIO;
> +	} else {
> +		err = 0;
> +	}
> +
> +	i915.enable_guc_submission = 0;
> +
> +	DRM_DEBUG_DRIVER("falling back to execlist mode, err %d\n", err);
> +
>   	return err;
>   }
>   
> @@ -588,8 +601,11 @@ void intel_guc_ucode_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;
> @@ -598,26 +614,21 @@ void intel_guc_ucode_init(struct drm_device *dev)
>   		guc_fw->guc_fw_major_wanted = 4;
>   		guc_fw->guc_fw_minor_wanted = 3;
>   	} 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);

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