[Intel-gfx] [PATCH 2/3] drm/i915/display: Do both crawl and squash when changing cdclk
Matt Roper
matthew.d.roper at intel.com
Fri Nov 18 00:53:10 UTC 2022
On Thu, Nov 17, 2022 at 03:00:01PM -0800, Anusha Srivatsa wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
>
> For MTL, changing cdclk from between certain frequencies has
> both squash and crawl. Use the current cdclk config and
> the new(desired) cdclk config to construtc a mid cdclk config.
s/construtc/construct/
> Set the cdclk twice:
> - Current cdclk -> mid cdclk
> - mid cdclk -> desired cdclk
>
> Driver should not take some Pcode mailbox communication
> in the cdclk path for platforms that are Display version 14 and later.
>
> v2: Add check in intel_modeset_calc_cdclk() to avoid cdclk
> change via modeset for platforms that support squash_crawl sequences(Ville)
>
> v3: Add checks for:
> - scenario where only slow clock is used and
> cdclk is actually 0 (bringing up display).
> - PLLs are on before looking up the waveform.
> - Squash and crawl capability checks.(Ville)
>
> v4: Rebase
> - Move checks to be more consistent (Ville)
> - Add comments (Bala)
> v5:
> - Further small changes. Move checks around.
> - Make if-else better looking (Ville)
>
> v6: MTl should not follow PUnit mailbox communication as the rest of
> gen11+ platforms.(Anusha)
>
> Cc: Clint Taylor <Clinton.A.Taylor at intel.com>
> Cc: Balasubramani Vivekanandan <balasubramani.vivekanandan at intel.com>
> Signed-off-by: Anusha Srivatsa <anusha.srivatsa at intel.com>
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
> drivers/gpu/drm/i915/display/intel_cdclk.c | 181 +++++++++++++++++----
> 1 file changed, 150 insertions(+), 31 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.c b/drivers/gpu/drm/i915/display/intel_cdclk.c
> index 25d01271dc09..1280a08b9c72 100644
> --- a/drivers/gpu/drm/i915/display/intel_cdclk.c
> +++ b/drivers/gpu/drm/i915/display/intel_cdclk.c
> @@ -1727,37 +1727,79 @@ static bool cdclk_pll_is_unknown(unsigned int vco)
> return vco == ~0;
> }
>
> -static void bxt_set_cdclk(struct drm_i915_private *dev_priv,
> - const struct intel_cdclk_config *cdclk_config,
> - enum pipe pipe)
> +static int cdclk_squash_divider(u16 waveform)
> +{
> + return hweight16(waveform ?: 0xffff);
> +}
> +
> +static bool cdclk_compute_crawl_and_squash_midpoint(struct drm_i915_private *i915,
> + const struct intel_cdclk_config *old_cdclk_config,
> + const struct intel_cdclk_config *new_cdclk_config,
> + struct intel_cdclk_config *mid_cdclk_config)
> +{
> + u16 old_waveform, new_waveform, mid_waveform;
> + int size = 16;
> + int div = 2;
> +
> + /* Return for vco ~0 (-1) and follow complete PLL disable and enable */
I don't think the mention of ~0 / -1 here is helpful; we added the
helper function to hide those low-level implementation details. Just
say something high-level about what you're actually trying to do like
"If the PLL is in an unknown state, force a complete disable and
re-enable."
Aside from that (and the typo in the commit message),
Reviewed-by: Matt Roper <matthew.d.roper at intel.com>
> + if (cdclk_pll_is_unknown(old_cdclk_config->vco))
> + return false;
> +
> + /* Return if both Squash and Crawl are not present */
> + if (!HAS_CDCLK_CRAWL(i915) || !HAS_CDCLK_SQUASH(i915))
> + return false;
> +
> + old_waveform = cdclk_squash_waveform(i915, old_cdclk_config->cdclk);
> + new_waveform = cdclk_squash_waveform(i915, new_cdclk_config->cdclk);
> +
> + /* Return if Squash only or Crawl only is the desired action */
> + if (old_cdclk_config->vco == 0 || new_cdclk_config->vco == 0 ||
> + old_cdclk_config->vco == new_cdclk_config->vco ||
> + old_waveform == new_waveform)
> + return false;
> +
> + *mid_cdclk_config = *new_cdclk_config;
> +
> + /*
> + * Populate the mid_cdclk_config accordingly.
> + * - If moving to a higher cdclk, the desired action is squashing.
> + * The mid cdclk config should have the new (squash) waveform.
> + * - If moving to a lower cdclk, the desired action is crawling.
> + * The mid cdclk config should have the new vco.
> + */
> +
> + if (cdclk_squash_divider(new_waveform) > cdclk_squash_divider(old_waveform)) {
> + mid_cdclk_config->vco = old_cdclk_config->vco;
> + mid_waveform = new_waveform;
> + } else {
> + mid_cdclk_config->vco = new_cdclk_config->vco;
> + mid_waveform = old_waveform;
> + }
> +
> + mid_cdclk_config->cdclk = DIV_ROUND_CLOSEST(cdclk_squash_divider(mid_waveform) *
> + mid_cdclk_config->vco, size * div);
> +
> + /* make sure the mid clock came out sane */
> +
> + drm_WARN_ON(&i915->drm, mid_cdclk_config->cdclk <
> + min(old_cdclk_config->cdclk, new_cdclk_config->cdclk));
> + drm_WARN_ON(&i915->drm, mid_cdclk_config->cdclk >
> + i915->display.cdclk.max_cdclk_freq);
> + drm_WARN_ON(&i915->drm, cdclk_squash_waveform(i915, mid_cdclk_config->cdclk) !=
> + mid_waveform);
> +
> + return true;
> +}
> +
> +static void _bxt_set_cdclk(struct drm_i915_private *dev_priv,
> + const struct intel_cdclk_config *cdclk_config,
> + enum pipe pipe)
> {
> int cdclk = cdclk_config->cdclk;
> int vco = cdclk_config->vco;
> u32 val;
> u16 waveform;
> int clock;
> - int ret;
> -
> - /* Inform power controller of upcoming frequency change. */
> - if (DISPLAY_VER(dev_priv) >= 11)
> - ret = skl_pcode_request(&dev_priv->uncore, SKL_PCODE_CDCLK_CONTROL,
> - SKL_CDCLK_PREPARE_FOR_CHANGE,
> - SKL_CDCLK_READY_FOR_CHANGE,
> - SKL_CDCLK_READY_FOR_CHANGE, 3);
> - else
> - /*
> - * BSpec requires us to wait up to 150usec, but that leads to
> - * timeouts; the 2ms used here is based on experiment.
> - */
> - ret = snb_pcode_write_timeout(&dev_priv->uncore,
> - HSW_PCODE_DE_WRITE_FREQ_REQ,
> - 0x80000000, 150, 2);
> - if (ret) {
> - drm_err(&dev_priv->drm,
> - "Failed to inform PCU about cdclk change (err %d, freq %d)\n",
> - ret, cdclk);
> - return;
> - }
>
> 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)) {
> @@ -1793,11 +1835,62 @@ static void bxt_set_cdclk(struct drm_i915_private *dev_priv,
>
> if (pipe != INVALID_PIPE)
> intel_crtc_wait_for_next_vblank(intel_crtc_for_pipe(dev_priv, pipe));
> +}
> +
> +static void bxt_set_cdclk(struct drm_i915_private *dev_priv,
> + const struct intel_cdclk_config *cdclk_config,
> + enum pipe pipe)
> +{
> + struct intel_cdclk_config mid_cdclk_config;
> + int cdclk = cdclk_config->cdclk;
> + int ret = 0;
> +
> + /*
> + * Inform power controller of upcoming frequency change.
> + * Display versions 14 and beyond do not follow the PUnit
> + * mailbox communication, skip
> + * this step.
> + */
> + if (DISPLAY_VER(dev_priv) >= 14)
> + /* NOOP */;
> + else if (DISPLAY_VER(dev_priv) >= 11)
> + ret = skl_pcode_request(&dev_priv->uncore, SKL_PCODE_CDCLK_CONTROL,
> + SKL_CDCLK_PREPARE_FOR_CHANGE,
> + SKL_CDCLK_READY_FOR_CHANGE,
> + SKL_CDCLK_READY_FOR_CHANGE, 3);
> + else
> + /*
> + * BSpec requires us to wait up to 150usec, but that leads to
> + * timeouts; the 2ms used here is based on experiment.
> + */
> + ret = snb_pcode_write_timeout(&dev_priv->uncore,
> + HSW_PCODE_DE_WRITE_FREQ_REQ,
> + 0x80000000, 150, 2);
> +
> + if (ret) {
> + drm_err(&dev_priv->drm,
> + "Failed to inform PCU about cdclk change (err %d, freq %d)\n",
> + ret, cdclk);
> + return;
> + }
>
> - if (DISPLAY_VER(dev_priv) >= 11) {
> + if (cdclk_compute_crawl_and_squash_midpoint(dev_priv, &dev_priv->display.cdclk.hw,
> + cdclk_config, &mid_cdclk_config)) {
> + _bxt_set_cdclk(dev_priv, &mid_cdclk_config, pipe);
> + _bxt_set_cdclk(dev_priv, cdclk_config, pipe);
> + } else {
> + _bxt_set_cdclk(dev_priv, cdclk_config, pipe);
> + }
> +
> + if (DISPLAY_VER(dev_priv) >= 14)
> + /*
> + * NOOP - No Pcode communication needed for
> + * Display versions 14 and beyond
> + */;
> + else if (DISPLAY_VER(dev_priv) >= 11)
> ret = snb_pcode_write(&dev_priv->uncore, SKL_PCODE_CDCLK_CONTROL,
> cdclk_config->voltage_level);
> - } else {
> + else
> /*
> * The timeout isn't specified, the 2ms used here is based on
> * experiment.
> @@ -1808,7 +1901,6 @@ static void bxt_set_cdclk(struct drm_i915_private *dev_priv,
> HSW_PCODE_DE_WRITE_FREQ_REQ,
> cdclk_config->voltage_level,
> 150, 2);
> - }
>
> if (ret) {
> drm_err(&dev_priv->drm,
> @@ -1965,6 +2057,28 @@ void intel_cdclk_uninit_hw(struct drm_i915_private *i915)
> skl_cdclk_uninit_hw(i915);
> }
>
> +static bool intel_cdclk_can_crawl_and_squash(struct drm_i915_private *i915,
> + const struct intel_cdclk_config *a,
> + const struct intel_cdclk_config *b)
> +{
> + u16 old_waveform;
> + u16 new_waveform;
> +
> + drm_WARN_ON(&i915->drm, cdclk_pll_is_unknown(a->vco));
> +
> + if (a->vco == 0 || b->vco == 0)
> + return false;
> +
> + if (!HAS_CDCLK_CRAWL(i915) || !HAS_CDCLK_SQUASH(i915))
> + return false;
> +
> + old_waveform = cdclk_squash_waveform(i915, a->cdclk);
> + new_waveform = cdclk_squash_waveform(i915, b->cdclk);
> +
> + return a->vco != b->vco &&
> + old_waveform != new_waveform;
> +}
> +
> static bool intel_cdclk_can_crawl(struct drm_i915_private *dev_priv,
> const struct intel_cdclk_config *a,
> const struct intel_cdclk_config *b)
> @@ -2771,9 +2885,14 @@ int intel_modeset_calc_cdclk(struct intel_atomic_state *state)
> pipe = INVALID_PIPE;
> }
>
> - if (intel_cdclk_can_squash(dev_priv,
> - &old_cdclk_state->actual,
> - &new_cdclk_state->actual)) {
> + if (intel_cdclk_can_crawl_and_squash(dev_priv,
> + &old_cdclk_state->actual,
> + &new_cdclk_state->actual)) {
> + drm_dbg_kms(&dev_priv->drm,
> + "Can change cdclk via crawling and squashing\n");
> + } else if (intel_cdclk_can_squash(dev_priv,
> + &old_cdclk_state->actual,
> + &new_cdclk_state->actual)) {
> drm_dbg_kms(&dev_priv->drm,
> "Can change cdclk via squashing\n");
> } else if (intel_cdclk_can_crawl(dev_priv,
> --
> 2.25.1
>
--
Matt Roper
Graphics Software Engineer
VTT-OSGC Platform Enablement
Intel Corporation
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