> -----Original Message-----
> From: Ville Syrjälä <ville.syrj...@linux.intel.com>
> Sent: Wednesday, September 28, 2022 12:24 PM
> To: Srivatsa, Anusha <anusha.sriva...@intel.com>
> Cc: intel-gfx@lists.freedesktop.org
> Subject: Re: [Intel-gfx] [PATCH 2/2] drm/i915/display: Add CDCLK Support for
> MTL
>
> On Wed, Sep 28, 2022 at 12:04:15PM -0700, Anusha Srivatsa wrote:
> > As per bSpec MTL has 38.4 MHz Reference clock.
> > MTL does support squasher like DG2 but only for lower frequencies.
> > Change the has_cdclk_squasher() helper to reflect this.
> >
> > bxt_get_cdclk() is not properly calculating HW clock for MTL, because
> > the squash formula is only prepared for DG2.
> > Apart from adding the cdclk table, align cdclk support with the new
> > cdclk_crawl_and_squash() introduced in previous patch.
> >
> > BSpec: 65243
> > Cc: Radhakrishna Sripada <radhakrishna.srip...@intel.com>
> > Signed-off-by: Anusha Srivatsa <anusha.sriva...@intel.com>
> > ---
> > drivers/gpu/drm/i915/display/intel_cdclk.c | 95
> > +++++++++++++++++++++-
> > 1 file changed, 93 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.c
> > b/drivers/gpu/drm/i915/display/intel_cdclk.c
> > index f7bc1013b149..6271eed0d7cf 100644
> > --- a/drivers/gpu/drm/i915/display/intel_cdclk.c
> > +++ b/drivers/gpu/drm/i915/display/intel_cdclk.c
> > @@ -1222,7 +1222,7 @@ static void skl_cdclk_uninit_hw(struct
> > drm_i915_private *dev_priv)
> >
> > static bool has_cdclk_squasher(struct drm_i915_private *i915) {
> > - return IS_DG2(i915);
> > + return DISPLAY_VER(i915) >= 14 || IS_DG2(i915);
> > }
> >
> > struct intel_cdclk_vals {
> > @@ -1350,6 +1350,16 @@ static const struct intel_cdclk_vals
> dg2_cdclk_table[] = {
> > {}
> > };
> >
> > +static const struct intel_cdclk_vals mtl_cdclk_table[] = {
> > + { .refclk = 38400, .cdclk = 172800, .divider = 2, .ratio = 16, .waveform
> = 0xad5a },
> > + { .refclk = 38400, .cdclk = 192000, .divider = 2, .ratio = 16, .waveform
> = 0xb6b6 },
> > + { .refclk = 38400, .cdclk = 307200, .divider = 2, .ratio = 16, .waveform
> = 0x0000 },
> > + { .refclk = 38400, .cdclk = 480000, .divider = 2, .ratio = 25, .waveform
> = 0x0000 },
> > + { .refclk = 38400, .cdclk = 556800, .divider = 2, .ratio = 29, .waveform
> = 0x0000 },
> > + { .refclk = 38400, .cdclk = 652800, .divider = 2, .ratio = 34, .waveform
> = 0x0000 },
> > + {}
> > +};
> > +
> > static int bxt_calc_cdclk(struct drm_i915_private *dev_priv, int
> > min_cdclk) {
> > const struct intel_cdclk_vals *table =
> > dev_priv->display.cdclk.table; @@ -1479,6 +1489,76 @@ static void
> bxt_de_pll_readout(struct drm_i915_private *dev_priv,
> > cdclk_config->vco = ratio * cdclk_config->ref; }
> >
> > +static void mtl_get_cdclk(struct drm_i915_private *i915,
> > + struct intel_cdclk_config *cdclk_config) {
> > + const struct intel_cdclk_vals *table = i915->display.cdclk.table;
> > + u32 squash_ctl, divider, waveform;
> > + int div, i, ratio;
> > +
> > + bxt_de_pll_readout(i915, cdclk_config);
> > +
> > + cdclk_config->bypass = cdclk_config->ref / 2;
> > +
> > + if (cdclk_config->vco == 0) {
> > + cdclk_config->cdclk = cdclk_config->bypass;
> > + goto out;
> > + }
> > +
> > + divider = intel_de_read(i915, CDCLK_CTL) &
> BXT_CDCLK_CD2X_DIV_SEL_MASK;
> > + switch (divider) {
> > + case BXT_CDCLK_CD2X_DIV_SEL_1:
> > + div = 2;
> > + break;
> > + case BXT_CDCLK_CD2X_DIV_SEL_1_5:
> > + div = 3;
> > + break;
> > + case BXT_CDCLK_CD2X_DIV_SEL_2:
> > + div = 4;
> > + break;
> > + case BXT_CDCLK_CD2X_DIV_SEL_4:
> > + div = 8;
> > + break;
> > + default:
> > + MISSING_CASE(divider);
> > + return;
> > + }
> > +
> > + squash_ctl = intel_de_read(i915, CDCLK_SQUASH_CTL);
> > + if (squash_ctl & CDCLK_SQUASH_ENABLE)
> > + waveform = squash_ctl &
> CDCLK_SQUASH_WAVEFORM_MASK;
> > + else
> > + waveform = 0;
> > +
> > + ratio = cdclk_config->vco / cdclk_config->ref;
> > +
> > + for (i = 0, cdclk_config->cdclk = 0; table[i].refclk; i++) {
> > + if (table[i].refclk != cdclk_config->ref)
> > + continue;
> > +
> > + if (table[i].divider != div)
> > + continue;
> > +
> > + if (table[i].waveform != waveform)
> > + continue;
> > +
> > + if (table[i].ratio != ratio)
> > + continue;
> > +
> > + cdclk_config->cdclk = table[i].cdclk;
> > + break;
> > + }
>
> NAK. Readout must not depend on these tables. Otherwise it's not proper
> readout and bugs can slip through. What is the supposed problem with the
> already existing code?
IIRC we were getting wrong values with the existing mathematical calculations
for cdclk. This way we force to pick an entry from the table.
Anusha
> > +out:
> > + /*
> > + * Can't read this out :( Let's assume it's
> > + * at least what the CDCLK frequency requires.
> > + */
> > + cdclk_config->voltage_level =
> > + intel_cdclk_calc_voltage_level(i915, cdclk_config->cdclk); }
> > +
> > +
> > static void bxt_get_cdclk(struct drm_i915_private *dev_priv,
> > struct intel_cdclk_config *cdclk_config) { @@ -
> 3138,6 +3218,13
> > @@ u32 intel_read_rawclk(struct drm_i915_private *dev_priv)
> > return freq;
> > }
> >
> > +static const struct intel_cdclk_funcs mtl_cdclk_funcs = {
> > + .get_cdclk = mtl_get_cdclk,
> > + .set_cdclk = bxt_set_cdclk,
> > + .modeset_calc_cdclk = bxt_modeset_calc_cdclk,
> > + .calc_voltage_level = tgl_calc_voltage_level, };
> > +
> > static const struct intel_cdclk_funcs tgl_cdclk_funcs = {
> > .get_cdclk = bxt_get_cdclk,
> > .set_cdclk = bxt_set_cdclk,
> > @@ -3273,7 +3360,11 @@ static const struct intel_cdclk_funcs
> i830_cdclk_funcs = {
> > */
> > void intel_init_cdclk_hooks(struct drm_i915_private *dev_priv) {
> > - if (IS_DG2(dev_priv)) {
> > +
> > + if (IS_METEORLAKE(dev_priv)) {
> > + dev_priv->display.funcs.cdclk = &mtl_cdclk_funcs;
> > + dev_priv->display.cdclk.table = mtl_cdclk_table;
> > + } else if (IS_DG2(dev_priv)) {
> > dev_priv->display.funcs.cdclk = &tgl_cdclk_funcs;
> > dev_priv->display.cdclk.table = dg2_cdclk_table;
> > } else if (IS_ALDERLAKE_P(dev_priv)) {
> > --
> > 2.25.1
>
> --
> Ville Syrjälä
> Intel
