Re: [PATCH v2 3/3] drm/i915: Add boot paramter to control rps boost at boot time.

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, Mar 13, 2014 at 09:30:18PM +0530, deepak.s@linux.intel.com wrote:
> From: Deepak S <deepak.s@intel.com>
> 
> We are adding a module paramter to control rps boost. By default, we
> enable the boost for better performace. Based on the need (perf/power)
> we can either enable/disable.
> 
> v2: Addressed rps default comment (Jani)
> 
> Signed-off-by: Deepak S <deepak.s@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.h    |  1 +
>  drivers/gpu/drm/i915/i915_gem.c    | 16 +++++++++++++++-
>  drivers/gpu/drm/i915/i915_params.c |  5 +++++
>  3 files changed, 21 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 607042b..7808319 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -2106,6 +2106,7 @@ struct i915_params {
>  	int panel_use_ssc;
>  	int vbt_sdvo_panel_type;
>  	int enable_rc6;
> +	int enable_rps_boost;

Should be bool like Jani said. And then it should be thrown somewhere
somewhere at the end of the structure next to the other bools.

>  	int enable_fbc;
>  	int enable_ppgtt;
>  	int enable_psr;
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 92b0b41..23a4700 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -1002,6 +1002,17 @@ static bool can_wait_boost(struct drm_i915_file_private *file_priv)
>  	return !atomic_xchg(&file_priv->rps_wait_boost, true);
>  }
>  
> +static int  intel_enable_rps_boost(struct drm_device *dev)
> +{
> +	/* No RPS Boost before Ironlake */

This comment is still wrong. I'd just drop it, everyone should know what
the gen check below means.

> +	if (INTEL_INFO(dev)->gen < 6)
> +		return 0;
> +
> +	/* Respect the kernel parameter if it is set */

This comment too seems rather obvious. I'd drop it as well.

> +	return i915.enable_rps_boost;
> +
> +}

This function is still just a wrapper for i915.enable_rps_boost since
__wait_seqno() already does the gen check. You could just check
i915.enable_rps_boost directly in __wait_seqno(). The other option is
to just drop the gen check from __wait_seqno() and just let this
function take care of it. Hmm. Yeah that might be the nicest choice in
fact.

> +
>  /**
>   * __wait_seqno - wait until execution of seqno has finished
>   * @ring: the ring expected to report seqno
> @@ -1042,8 +1053,11 @@ static int __wait_seqno(struct intel_ring_buffer *ring, u32 seqno,
>  
>  	timeout_expire = timeout ? jiffies + timespec_to_jiffies_timeout(timeout) : 0;
>  
> -	if (INTEL_INFO(dev)->gen >= 6 && can_wait_boost(file_priv)) {
> +	if (INTEL_INFO(dev)->gen >= 6 && can_wait_boost(file_priv) && 
> +			intel_enable_rps_boost(ring->dev)) {

Indentation is quite wrong. There's also trailing whitespace around
these parts. Please run patches through checkpatch.pl before submitting.

> +		
>  		gen6_rps_boost(dev_priv);
> +
>  		if (file_priv)
>  			mod_delayed_work(dev_priv->wq,
>  					 &file_priv->mm.idle_work,
> diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
> index a66ffb6..2d207e3 100644
> --- a/drivers/gpu/drm/i915/i915_params.c
> +++ b/drivers/gpu/drm/i915/i915_params.c
> @@ -34,6 +34,7 @@ struct i915_params i915 __read_mostly = {
>  	.panel_use_ssc = -1,
>  	.vbt_sdvo_panel_type = -1,
>  	.enable_rc6 = -1,
> +	.enable_rps_boost = 1,

true

>  	.enable_fbc = -1,
>  	.enable_hangcheck = true,
>  	.enable_ppgtt = -1,
> @@ -78,6 +79,10 @@ MODULE_PARM_DESC(enable_rc6,
>  	"For example, 3 would enable rc6 and deep rc6, and 7 would enable everything. "
>  	"default: -1 (use per-chip default)");
>  
> +module_param_named(enable_rps_boost, i915.enable_rps_boost, int, 0600);

bool

> +MODULE_PARM_DESC(enable_rps_boost,
> +		"Enable/Disable boost RPS frequency (default: enabled (1))");

default: true

> +
>  module_param_named(enable_fbc, i915.enable_fbc, int, 0600);
>  MODULE_PARM_DESC(enable_fbc,
>  	"Enable frame buffer compression for power savings "
> -- 
> 1.8.4.2
> 
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-- 
Ville Syrjälä
Intel OTC