[Intel-gfx] [RFC] drm/i915: add slice shutdown debugfs interface

[Chris Wilson]

On Fri, Apr 07, 2017 at 03:41:41AM -0700, Dmitry Rogozhkin wrote:
> Slice shutdown override interface (i915_slice_enabled) permits
> to power on/off GPGPU slices in Gen8 and Gen9. This is helpful
> in performance investigations amd checking scalability across
> hw platforms.
> 
> Change-Id: I4f2fe5fefb8d1df4519fd0eb58237759c7d1a930
> Signed-off-by: Dmitry Rogozhkin <dmitry.v.rogozhkin at intel.com>
> CC: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> CC: Zhipeng Gong <zhipeng.gong at intel.com>
> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/i915_debugfs.c      | 36 +++++++++++++++++++++++++++++++-
>  drivers/gpu/drm/i915/i915_drv.h          |  1 +
>  drivers/gpu/drm/i915/intel_device_info.c |  1 +
>  drivers/gpu/drm/i915/intel_lrc.c         |  4 ++--
>  4 files changed, 39 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index d689e51..977bdb03 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -4812,6 +4812,39 @@ static int i915_hpd_storm_ctl_open(struct inode *inode, struct file *file)
>  	{"i915_drrs_status", i915_drrs_status, 0},
>  	{"i915_rps_boost_info", i915_rps_boost_info, 0},
>  };
> +
> +static int
> +i915_slice_enabled_get(void *data, u64 *val)
> +{
> +	struct drm_device *dev = data;

? data is the drm_i915_private pointer.

> +	struct drm_i915_private *dev_priv = to_i915(dev);
> +
> +	*val = INTEL_INFO(dev_priv)->sseu.slice_enabled;
> +	return 0;
> +}
> +
> +static int
> +i915_slice_enabled_set(void *data, u64 val)
> +{
> +	struct drm_device *dev = data;
> +	struct drm_i915_private *dev_priv = to_i915(dev);
> +	struct intel_device_info *info;
> +
> +	info = mkwrite_device_info(dev_priv);
> +	if (!IS_SKYLAKE(dev_priv) || !info->sseu.has_slice_pg)
> +		return -EINVAL;
> +
> +	if (val > hweight8(info->sseu.slice_mask))
> +		return -EINVAL;
> +
> +	info->sseu.slice_enabled = (u8)val;

Why the explicit cast?

> +	return 0;
> +}
> +
> +DEFINE_SIMPLE_ATTRIBUTE(i915_slice_enabled_fops,
> +			i915_slice_enabled_get, i915_slice_enabled_set,
> +			"%llu\n");
> +
>  #define I915_DEBUGFS_ENTRIES ARRAY_SIZE(i915_debugfs_list)
>  
>  static const struct i915_debugfs_files {
> @@ -4839,7 +4872,8 @@ static int i915_hpd_storm_ctl_open(struct inode *inode, struct file *file)
>  	{"i915_dp_test_type", &i915_displayport_test_type_fops},
>  	{"i915_dp_test_active", &i915_displayport_test_active_fops},
>  	{"i915_guc_log_control", &i915_guc_log_control_fops},
> -	{"i915_hpd_storm_ctl", &i915_hpd_storm_ctl_fops}
> +	{"i915_hpd_storm_ctl", &i915_hpd_storm_ctl_fops},
> +	{"i915_slice_enabled", &i915_slice_enabled_fops}
>  };
>  
>  int i915_debugfs_register(struct drm_i915_private *dev_priv)
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index bb6fc1e..7455d43 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -852,6 +852,7 @@ struct sseu_dev_info {
>  	u8 has_slice_pg:1;
>  	u8 has_subslice_pg:1;
>  	u8 has_eu_pg:1;
> +	u8 slice_enabled;
>  };
>  
>  static inline unsigned int sseu_subslice_total(const struct sseu_dev_info *sseu)
> diff --git a/drivers/gpu/drm/i915/intel_device_info.c b/drivers/gpu/drm/i915/intel_device_info.c
> index 7d01dfe..2eee76b 100644
> --- a/drivers/gpu/drm/i915/intel_device_info.c
> +++ b/drivers/gpu/drm/i915/intel_device_info.c
> @@ -412,6 +412,7 @@ void intel_device_info_runtime_init(struct drm_i915_private *dev_priv)
>  		gen9_sseu_info_init(dev_priv);
>  
>  	info->has_snoop = !info->has_llc;
> +	info->sseu.slice_enabled = hweight8(info->sseu.slice_mask);
>  
>  	DRM_DEBUG_DRIVER("slice mask: %04x\n", info->sseu.slice_mask);
>  	DRM_DEBUG_DRIVER("slice total: %u\n", hweight8(info->sseu.slice_mask));
> diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
> index 0dc1cc4..bc650df 100644
> --- a/drivers/gpu/drm/i915/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/intel_lrc.c
> @@ -1732,7 +1732,7 @@ int logical_xcs_ring_init(struct intel_engine_cs *engine)
>  	 * No explicit RPCS request is needed to ensure full
>  	 * slice/subslice/EU enablement prior to Gen9.
>  	*/
> -	if (INTEL_GEN(dev_priv) < 9)
> +	if (INTEL_GEN(dev_priv) < 8)

Unrelated?

>  		return 0;
>  
>  	/*
> @@ -1743,7 +1743,7 @@ int logical_xcs_ring_init(struct intel_engine_cs *engine)
>  	*/
>  	if (INTEL_INFO(dev_priv)->sseu.has_slice_pg) {
>  		rpcs |= GEN8_RPCS_S_CNT_ENABLE;
> -		rpcs |= hweight8(INTEL_INFO(dev_priv)->sseu.slice_mask) <<
> +		rpcs |= INTEL_INFO(dev_priv)->sseu.slice_enabled <<
>  			GEN8_RPCS_S_CNT_SHIFT;

logical_xcs_ring_init() is never called after debugfs is registered.
What is the connection to the debugfs interface?
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre