Re: [Intel-gfx] [PATCH] drm/i915: Add i915.enable_sagv modparam

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Wed, Mar 22, 2023 at 08:12:19PM +0200, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> Currently we have no sane way to forcibly disable SAGV, which
> makes debugging things a PITA. Manually poking at the pcode
> mailbox with it's various SAGV/QGV/PSF formats is no fun,
> and likely to be clobbered by the driver anyway.
> 
> Let's add a modparam for this.
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/display/skl_watermark.c | 4 ++++
>  drivers/gpu/drm/i915/i915_params.c           | 3 +++
>  drivers/gpu/drm/i915/i915_params.h           | 1 +
>  3 files changed, 8 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/skl_watermark.c b/drivers/gpu/drm/i915/display/skl_watermark.c
> index 50a9a6adbe32..ff70225c0263 100644
> --- a/drivers/gpu/drm/i915/display/skl_watermark.c
> +++ b/drivers/gpu/drm/i915/display/skl_watermark.c
> @@ -411,6 +411,9 @@ static bool intel_crtc_can_enable_sagv(const struct intel_crtc_state *crtc_state
>  	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
>  	struct drm_i915_private *i915 = to_i915(crtc->base.dev);
>  
> +	if (!i915->params.enable_sagv)
> +		return false;

would this be one more ifdef for xe?
should we hide this on a HAS_SAGV?

anyway, let's move on:

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>


> +
>  	if (DISPLAY_VER(i915) >= 12)
>  		return tgl_crtc_can_enable_sagv(crtc_state);
>  	else
> @@ -3696,6 +3699,7 @@ static int intel_sagv_status_show(struct seq_file *m, void *unused)
>  	};
>  
>  	seq_printf(m, "SAGV available: %s\n", str_yes_no(intel_has_sagv(i915)));
> +	seq_printf(m, "SAGV modparam: %s\n", str_enabled_disabled(i915->params.enable_sagv));
>  	seq_printf(m, "SAGV status: %s\n", sagv_status[i915->display.sagv.status]);
>  	seq_printf(m, "SAGV block time: %d usec\n", i915->display.sagv.block_time_us);
>  
> diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
> index ade744cccfea..66141906ea05 100644
> --- a/drivers/gpu/drm/i915/i915_params.c
> +++ b/drivers/gpu/drm/i915/i915_params.c
> @@ -121,6 +121,9 @@ i915_param_named_unsafe(enable_psr2_sel_fetch, bool, 0400,
>  	"(0=disabled, 1=enabled) "
>  	"Default: 0");
>  
> +i915_param_named_unsafe(enable_sagv, bool, 0600,
> +	"Enable system agent voltage/frequency scaling (SAGV) (default: true)");
> +
>  i915_param_named_unsafe(force_probe, charp, 0400,
>  	"Force probe options for specified supported devices. "
>  	"See CONFIG_DRM_I915_FORCE_PROBE for details.");
> diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
> index 3f51f90145b6..6798b5c2363d 100644
> --- a/drivers/gpu/drm/i915/i915_params.h
> +++ b/drivers/gpu/drm/i915/i915_params.h
> @@ -56,6 +56,7 @@ struct drm_printer;
>  	param(int, enable_psr, -1, 0600) \
>  	param(bool, psr_safest_params, false, 0400) \
>  	param(bool, enable_psr2_sel_fetch, true, 0400) \
> +	param(bool, enable_sagv, true, 0600) \
>  	param(int, disable_power_well, -1, 0400) \
>  	param(int, enable_ips, 1, 0600) \
>  	param(int, invert_brightness, 0, 0600) \
> -- 
> 2.39.2
>