On Fri, Nov 19, 2021 at 03:13:47PM +0200, Mika Kahola wrote:
> To calculate CD clock with squasher unit, we set CD clock ratio to fixed value of 34.
> The CD clock value is read from CD clock squasher table.
>
> BSpec: 54034
>
> v2: Read ratio from register (Ville)
> Drop unnecessary local variable (Ville)
> Get CD clock from the given table
> v3: Calculate CD clock frequency based on waveform bit pattern (Ville)
> [v4: vsyrjala: Actually do a proper blind readout from the hardware]
> [v5: vsyrjala: Use has_cdclk_squasher()]
>
Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@xxxxxxxxx>
> Signed-off-by: Mika Kahola <mika.kahola@xxxxxxxxx>
> Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/intel_cdclk.c | 17 ++++++++++++++++-
> 1 file changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.c b/drivers/gpu/drm/i915/display/intel_cdclk.c
> index 560383e8c5b6..5fcb393079f7 100644
> --- a/drivers/gpu/drm/i915/display/intel_cdclk.c
> +++ b/drivers/gpu/drm/i915/display/intel_cdclk.c
> @@ -1466,6 +1466,7 @@ static void bxt_de_pll_readout(struct drm_i915_private *dev_priv,
> static void bxt_get_cdclk(struct drm_i915_private *dev_priv,
> struct intel_cdclk_config *cdclk_config)
> {
> + u32 squash_ctl = 0;
> u32 divider;
> int div;
>
> @@ -1503,7 +1504,21 @@ static void bxt_get_cdclk(struct drm_i915_private *dev_priv,
> return;
> }
>
> - cdclk_config->cdclk = DIV_ROUND_CLOSEST(cdclk_config->vco, div);
> + if (has_cdclk_squasher(dev_priv))
> + squash_ctl = intel_de_read(dev_priv, CDCLK_SQUASH_CTL);
> +
> + if (squash_ctl & CDCLK_SQUASH_ENABLE) {
> + u16 waveform;
> + int size;
> +
> + size = REG_FIELD_GET(CDCLK_SQUASH_WINDOW_SIZE_MASK, squash_ctl) + 1;
> + waveform = REG_FIELD_GET(CDCLK_SQUASH_WAVEFORM_MASK, squash_ctl) >> (16 - size);
> +
> + cdclk_config->cdclk = DIV_ROUND_CLOSEST(hweight16(waveform) *
> + cdclk_config->vco, size * div);
> + } else {
> + cdclk_config->cdclk = DIV_ROUND_CLOSEST(cdclk_config->vco, div);
> + }
>
> out:
> /*
> --
> 2.27.0
>
