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

Ville Syrjälä
2014-03-13T18:24:28Z

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