Re: [PATCH v6 3/7] drm/i915/guc: add enable_guc_loading parameter

[Nick Hoath <nicholas.hoath@xxxxxxxxx>]

On 20/05/2016 11:42, Tvrtko Ursulin wrote:
> From: Dave Gordon <david.s.gordon@xxxxxxxxx>
>
> 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.
>
> v5:
>      Dropped one more error message, disabled GuC submission on
>      hypothetical firmware-free devices [Tvrtko Ursulin].
>
> v6:
>      Logging tidy by Tvrtko Ursulin:
>       * Do not log falling back to execlists when wedging the GPU.
>       * Do not log fw load errors when load was disabled by user.
>       * Pass down some error code from fw load for log message to
>         make more sense.
>
> Signed-off-by: Dave Gordon <david.s.gordon@xxxxxxxxx>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxxxxxxx>
> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> (v5)
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Reviewed-by: Nick Hoath <nicholas.hoath@xxxxxxxxx> (v6)
> ---
>   drivers/gpu/drm/i915/i915_gem.c            |   5 +-
>   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    | 123 +++++++++++++++++------------
>   5 files changed, 89 insertions(+), 60 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 88dce5482f2f..1a3a07eca0d0 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -4868,11 +4868,8 @@ i915_gem_init_hw(struct drm_device *dev)
>   	/* We can't enable contexts until all firmware is loaded */
>   	if (HAS_GUC(dev)) {
>   		ret = intel_guc_setup(dev);
> -		if (ret) {
> -			DRM_ERROR("Failed to initialize GuC, error %d\n", ret);
> -			ret = -EIO;
> +		if (ret)
>   			goto out;
> -		}
>   	}
>
>   	/*
> diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c
> index 169242a8adff..916cd6778cf3 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;
>
>   	ctx = dev_priv->kernel_context;
> diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
> index cd74fb8e9387..21a323c01cdb 100644
> --- a/drivers/gpu/drm/i915/i915_params.c
> +++ b/drivers/gpu/drm/i915/i915_params.c
> @@ -53,7 +53,8 @@ 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,
> @@ -193,8 +194,15 @@ MODULE_PARM_DESC(edp_vswing,
>   		 "(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 dd0d0bbcc05b..658ce7379671 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 mmio_debug;
>   	int edp_vswing;
> @@ -56,7 +58,6 @@ 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 30ec8208dbbc..29273e5fee22 100644
> --- a/drivers/gpu/drm/i915/intel_guc_loader.c
> +++ b/drivers/gpu/drm/i915/intel_guc_loader.c
> @@ -402,50 +402,42 @@ 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;
>
> -	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);
> -
> -	if (guc_fw->guc_fw_fetch_status == GUC_FIRMWARE_NONE)
> -		return 0;
> -
> -	if (guc_fw->guc_fw_fetch_status == GUC_FIRMWARE_SUCCESS &&
> -	    guc_fw->guc_fw_load_status == GUC_FIRMWARE_FAIL)
> -		return -ENOEXEC;
> -
> -	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));
> +	/* Loading forbidden, or no firmware to load? */
> +	if (!i915.enable_guc_loading) {
> +		err = 0;
> +		goto fail;
> +	} else if (fw_path == NULL || *fw_path == '\0') {
> +		if (*fw_path == '\0')
> +			DRM_INFO("No GuC firmware known for this platform\n");
> +		err = -ENODEV;
> +		goto fail;
> +	}
>
> -	switch (guc_fw->guc_fw_fetch_status) {
> -	case GUC_FIRMWARE_FAIL:
> -		/* something went wrong :( */
> +	/* Fetch failed, or already fetched but failed to load? */
> +	if (guc_fw->guc_fw_fetch_status != GUC_FIRMWARE_SUCCESS) {
>   		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;
> +	} else if (guc_fw->guc_fw_load_status == GUC_FIRMWARE_FAIL) {
> +		err = -ENOEXEC;
>   		goto fail;
> -
> -	case GUC_FIRMWARE_SUCCESS:
> -		break;
>   	}
>
> +	direct_interrupts_to_host(dev_priv);
> +
> +	guc_fw->guc_fw_load_status = GUC_FIRMWARE_PENDING;
> +
> +	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)
>   		goto fail;
> @@ -463,7 +455,7 @@ int intel_guc_setup(struct drm_device *dev)
>   		 */
>   		err = i915_reset_guc(dev_priv);
>   		if (err) {
> -			DRM_ERROR("GuC reset failed, err %d\n", err);
> +			DRM_ERROR("GuC reset failed: %d\n", err);
>   			goto fail;
>   		}
>
> @@ -474,8 +466,8 @@ int intel_guc_setup(struct drm_device *dev)
>   		if (--retries == 0)
>   			goto fail;
>
> -		DRM_INFO("GuC fw load failed, err %d; will reset and "
> -			"retry %d more time(s)\n", err, retries);
> +		DRM_INFO("GuC fw load failed: %d; will reset and "
> +			 "retry %d more time(s)\n", err, retries);
>   	}
>
>   	guc_fw->guc_fw_load_status = GUC_FIRMWARE_SUCCESS;
> @@ -497,7 +489,6 @@ 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;
>
> @@ -505,7 +496,41 @@ fail:
>   	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 (i915.enable_guc_submission > 1) {
> +		ret = -EIO;
> +	} else {
> +		ret = 0;
> +	}
> +
> +	if (err == 0)
> +		DRM_INFO("GuC firmware load skipped\n");
> +	else if (ret == -EIO)
> +		DRM_ERROR("GuC firmware load failed: %d\n", err);
> +	else
> +		DRM_INFO("GuC firmware load failed: %d\n", err);
> +
> +	if (i915.enable_guc_submission) {
> +		if (fw_path == NULL)
> +			DRM_INFO("GuC submission without firmware not supported\n");
> +		if (ret == 0)
> +			DRM_INFO("Falling back to execlist mode\n");
> +		else
> +			DRM_ERROR("GuC init failed: %d\n", ret);
> +	}
> +	i915.enable_guc_submission = 0;
> +
> +	return ret;
>   }
>
>   static void guc_fw_fetch(struct drm_device *dev, struct intel_guc_fw *guc_fw)
> @@ -644,8 +669,11 @@ 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;
> @@ -658,26 +686,21 @@ 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);

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