Re: drm/i915/slpc: Add enable_slpc module parameter

[David Weinehall <tao@acc.umu.se>]

On Sat, Aug 20, 2016 at 10:39:04AM +0530, Sagar Arun Kamble wrote:
> From: Tom O'Rourke <Tom.O'Rourke@intel.com>
> 
> i915.enable_slpc is used to override the default for slpc usage.
> The expected values are -1=auto, 0=disabled [default], 1=enabled.
> 
> slpc_enable_sanitize() converts i915.enable_slpc to either 0 or 1.
> Interpretation of default value is based on HAS_SLPC(), after
> slpc_version_check().  This function also enforces the requirement
> that guc_submission is required for slpc.
> 
> intel_slpc_enabled() returns 1 if SLPC should be used.
> 
> v2: Add early call to sanitize enable_slpc in intel_guc_ucode_init
> 
> v5: Remove sanitize enable_slpc call before firmware version check
>     is performed. (ChrisW)
>     Version check is added in next patch and that will be done as
>     part of slpc_enable_sanitize function in the next patch. (Sagar)
>     Updated slpc option sanitize function call for platforms without
>     GuC support. This was caught by CI BAT.
> 
> Suggested-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
> Signed-off-by: Tom O'Rourke <Tom.O'Rourke@intel.com>
> Signed-off-by: Sagar Arun Kamble <sagar.a.kamble@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_params.c      |  6 ++++++
>  drivers/gpu/drm/i915/i915_params.h      |  1 +
>  drivers/gpu/drm/i915/intel_guc.h        |  6 ++++++
>  drivers/gpu/drm/i915/intel_guc_loader.c | 30 ++++++++++++++++++++++++++----
>  4 files changed, 39 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
> index 768ad89..72b3097 100644
> --- a/drivers/gpu/drm/i915/i915_params.c
> +++ b/drivers/gpu/drm/i915/i915_params.c
> @@ -36,6 +36,7 @@ struct i915_params i915 __read_mostly = {
>  	.enable_dc = -1,
>  	.enable_fbc = -1,
>  	.enable_execlists = -1,
> +	.enable_slpc = 0,
>  	.enable_hangcheck = true,
>  	.enable_ppgtt = -1,
>  	.enable_psr = -1,
> @@ -131,6 +132,11 @@ MODULE_PARM_DESC(enable_execlists,
>  	"Override execlists usage. "
>  	"(-1=auto [default], 0=disabled, 1=enabled)");
>  
> +module_param_named_unsafe(enable_slpc, i915.enable_slpc, int, 0400);
> +MODULE_PARM_DESC(enable_slpc,
> +	"Override single-loop-power-controller (slpc) usage. "
> +	"(-1=auto, 0=disabled [default], 1=enabled)");
> +
>  module_param_named_unsafe(enable_psr, i915.enable_psr, int, 0600);
>  MODULE_PARM_DESC(enable_psr, "Enable PSR "
>  		 "(0=disabled, 1=enabled - link mode chosen per-platform, 2=force link-standby mode, 3=force link-off mode) "
> diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
> index 3a0dd78..391c471 100644
> --- a/drivers/gpu/drm/i915/i915_params.h
> +++ b/drivers/gpu/drm/i915/i915_params.h
> @@ -39,6 +39,7 @@ struct i915_params {
>  	int enable_fbc;
>  	int enable_ppgtt;
>  	int enable_execlists;
> +	int enable_slpc;
>  	int enable_psr;
>  	unsigned int preliminary_hw_support;
>  	int disable_power_well;
> diff --git a/drivers/gpu/drm/i915/intel_guc.h b/drivers/gpu/drm/i915/intel_guc.h
> index 9e6b948..27a7459 100644
> --- a/drivers/gpu/drm/i915/intel_guc.h
> +++ b/drivers/gpu/drm/i915/intel_guc.h
> @@ -146,6 +146,12 @@ struct intel_guc {
>  	uint32_t last_seqno[I915_NUM_ENGINES];
>  };
>  
> +static inline int intel_slpc_enabled(void)
> +{
> +        WARN_ON(i915.enable_slpc < 0);
> +        return i915.enable_slpc;
> +}
> +
>  /* intel_guc_loader.c */
>  extern void intel_guc_init(struct drm_device *dev);
>  extern int intel_guc_setup(struct drm_device *dev);
> diff --git a/drivers/gpu/drm/i915/intel_guc_loader.c b/drivers/gpu/drm/i915/intel_guc_loader.c
> index 324812d..75b360f 100644
> --- a/drivers/gpu/drm/i915/intel_guc_loader.c
> +++ b/drivers/gpu/drm/i915/intel_guc_loader.c
> @@ -144,6 +144,25 @@ static void direct_interrupts_to_guc(struct drm_i915_private *dev_priv)
>  	}
>  }
>  
> +static void sanitize_slpc_option(struct drm_device *dev)
> +{
> +	/* Handle default case */
> +	if (i915.enable_slpc < 0)
> +		i915.enable_slpc = HAS_SLPC(dev);
> +
> +	/* slpc requires hardware support and compatible firmware */
> +	if (!HAS_SLPC(dev))
> +		i915.enable_slpc = 0;

I'd prefer if you pass dev_priv to HAS_SLPC
(and thus pass in drm_i915_private * to the function instead).

> +
> +	/* slpc requires guc loaded */
> +	if (!i915.enable_guc_loading)
> +		i915.enable_slpc = 0;
> +
> +	/* slpc requires guc submission */
> +	if (!i915.enable_guc_submission)
> +		i915.enable_slpc = 0;
> +}
> +
>  static u32 get_gttype(struct drm_i915_private *dev_priv)
>  {
>  	/* XXX: GT type based on PCI device ID? field seems unused by fw */
> @@ -728,18 +747,21 @@ void intel_guc_init(struct drm_device *dev)
>  	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 */
> +	/* Return if GuC loading is disabled sanitizing SLPC option */
>  	if (!i915.enable_guc_loading)
> -		return;
> +		goto out;
>  	if (fw_path == NULL)
> -		return;
> +		goto out;
>  	if (*fw_path == '\0')
> -		return;
> +		goto out;
>  
>  	guc_fw->guc_fw_fetch_status = GUC_FIRMWARE_PENDING;
>  	DRM_DEBUG_DRIVER("GuC firmware pending, path %s\n", fw_path);
>  	guc_fw_fetch(dev, guc_fw);
>  	/* status must now be FAIL or SUCCESS */
> +
> +out:
> +	sanitize_slpc_option(dev);
>  }
>  
>  /**

Reviewed-by: David Weinehall <david.weinehall@linux.intel.com>
-- 
 /) David Weinehall <tao@acc.umu.se> /) Northern lights wander      (\
//  Maintainer of the v2.0 kernel   //  Dance across the winter sky //
\)  http://www.acc.umu.se/~tao/    (/   Full colour fire           (/
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