On Fri, Nov 11, 2022 at 11:26:02AM -0800, Anusha Srivatsa wrote:
> 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)
>
> Cc: Ville Syrjälä <[email protected]>
> Cc: Matt Roper <[email protected]>
> Suggested-by: Ville Syrjälä <[email protected]>
> Signed-off-by: Anusha Srivatsa <[email protected]>
> ---
> drivers/gpu/drm/i915/display/intel_cdclk.c | 13 ++++++++++++-
> 1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.c
> b/drivers/gpu/drm/i915/display/intel_cdclk.c
> index 8a9031012d74..2d9b7ba58358 100644
> --- a/drivers/gpu/drm/i915/display/intel_cdclk.c
> +++ b/drivers/gpu/drm/i915/display/intel_cdclk.c
> @@ -1716,6 +1716,16 @@ 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);
Pointless parens.
> +}
> +
> static void bxt_set_cdclk(struct drm_i915_private *dev_priv,
> const struct intel_cdclk_config *cdclk_config,
> enum pipe pipe)
> @@ -1748,7 +1758,8 @@ 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))) {
More pointless parens
With those removed
Reviewed-by: Ville Syrjälä <[email protected]>
Though I think we should probably add the pll_is_enabled()
helper too, just make the code a bit more self explanatory.
> if (dev_priv->display.cdclk.hw.vco != vco)
> adlp_cdclk_pll_crawl(dev_priv, vco);
> } else if (DISPLAY_VER(dev_priv) >= 11)
> --
> 2.25.1
--
Ville Syrjälä
Intel
