> -----Original Message-----
> From: Lisovskiy, Stanislav <stanislav.lisovskiy@xxxxxxxxx>
> Sent: Monday, January 30, 2023 5:59 AM
> To: intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> Cc: Lisovskiy, Stanislav <stanislav.lisovskiy@xxxxxxxxx>; Saarinen, Jani
> <jani.saarinen@xxxxxxxxx>; Srivatsa, Anusha <anusha.srivatsa@xxxxxxxxx>
> Subject: [PATCH] drm/i915: Implement workaround for CDCLK PLL
> disable/enable
>
> It was reported that we might get a hung and loss of register access in some
> cases when CDCLK PLL is disabled and then enabled, while squashing is enabled.
> As a workaround it was proposed by HW team that SW should disable squashing
> when CDCLK PLL is being reenabled.
>
> v2: - Added WA number comment(Rodrigo Vivi)
>
> Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@xxxxxxxxx>
Reviewed-by: Anusha Srivatsa <anusha.srivatsa@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/intel_cdclk.c | 15 +++++++++++++--
> 1 file changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.c
> b/drivers/gpu/drm/i915/display/intel_cdclk.c
> index 7e16b655c833..8ae2b4c81f31 100644
> --- a/drivers/gpu/drm/i915/display/intel_cdclk.c
> +++ b/drivers/gpu/drm/i915/display/intel_cdclk.c
> @@ -1801,6 +1801,13 @@ static bool
> cdclk_compute_crawl_and_squash_midpoint(struct drm_i915_private *i91
> return true;
> }
>
> +static bool pll_enable_wa_needed(struct drm_i915_private *dev_priv) {
> + return ((IS_DG2(dev_priv) || IS_METEORLAKE(dev_priv))
> + && dev_priv->display.cdclk.hw.vco > 0
> + && HAS_CDCLK_SQUASH(dev_priv));
> +}
> +
> static void _bxt_set_cdclk(struct drm_i915_private *dev_priv,
> const struct intel_cdclk_config *cdclk_config,
> enum pipe pipe)
> @@ -1815,9 +1822,13 @@ static void _bxt_set_cdclk(struct drm_i915_private
> *dev_priv,
> !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)
> + } else if (DISPLAY_VER(dev_priv) >= 11) {
> + /* wa_15010685871: dg2, mtl */
> + if (pll_enable_wa_needed(dev_priv))
> + dg2_cdclk_squash_program(dev_priv, 0);
> +
> icl_cdclk_pll_update(dev_priv, vco);
> - else
> + } else
> bxt_cdclk_pll_update(dev_priv, vco);
>
> waveform = cdclk_squash_waveform(dev_priv, cdclk);
> --
> 2.37.3
