Commit 9a0a4ec5 authored Nov 17, 2022 by Anusha Srivatsa

drm/i915/display: Add missing checks for cdclk crawling



cdclk_sanitize() function was written assuming vco was a signed integer.
vco gets assigned to -1 (essentially ~0) for the case where PLL
might be enabled and vco is not a frequency that will ever
get used. In such a scenario the right thing to do is disable the
PLL and re-enable it again with a valid frequency.
However the vco is declared as a unsigned variable.
With the above assumption, driver takes crawl path when not needed.
Add explicit check to not crawl in the case of an invalid PLL.

v2: Move the check from .h to .c (MattR)
- Move check to bxt_set_cdclk() instead of
intel_modeset_calc_cdclk() which is directly in
the path of the sanitize() function (Ville)

v3: remove unwanted parenthesis(Ville)

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Anusha Srivatsa <anusha.srivatsa@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221117230002.792096-1-anusha.srivatsa@intel.com

parent f322ed0d

drivers/gpu/drm/i915/display/intel_cdclk.c

+12 −1

Original line number	Diff line number	Diff line
		@@ -1717,6 +1717,16 @@ static void dg2_cdclk_squash_program(struct drm_i915_private *i915,
		intel_de_write(i915, CDCLK_SQUASH_CTL, squash_ctl);
		}

		static bool cdclk_pll_is_unknown(unsigned int vco)
		{
		/*
		* Ensure driver does not take the crawl path for the
		* case when the vco is set to ~0 in the
		* sanitize path.
		*/
		return vco == ~0;
		}

		static void bxt_set_cdclk(struct drm_i915_private *dev_priv,
		const struct intel_cdclk_config *cdclk_config,
		enum pipe pipe)
		@@ -1749,7 +1759,8 @@ static void bxt_set_cdclk(struct drm_i915_private *dev_priv,
		return;
		}

		if (HAS_CDCLK_CRAWL(dev_priv) && dev_priv->display.cdclk.hw.vco > 0 && vco > 0) {
		if (HAS_CDCLK_CRAWL(dev_priv) && dev_priv->display.cdclk.hw.vco > 0 && vco > 0 &&
		!cdclk_pll_is_unknown(dev_priv->display.cdclk.hw.vco)) {
		if (dev_priv->display.cdclk.hw.vco != vco)
		adlp_cdclk_pll_crawl(dev_priv, vco);
		} else if (DISPLAY_VER(dev_priv) >= 11)