Re: [PATCH 6/8] drm/i915/xe2lpd: Support MDCLK:CDCLK ratio changes

["Lisovskiy, Stanislav" <stanislav.lisovskiy@intel.com>]

On Mon, Mar 04, 2024 at 03:30:25PM -0300, Gustavo Sousa wrote:
> Commit 394b4b7df9f7 ("drm/i915/lnl: Add CDCLK table") and commit
> 3d3696c0fed1 ("drm/i915/lnl: Start using CDCLK through PLL") started
> adding support for CDCLK programming support for Xe2LPD. One final piece
> is missing, which is the programming necessary for changed in the ratio
> between MDCLK and CDCLK. Let's do that now.
> 
> BSpec instructs us to update MBUS_CTL and DBUF_CTL_S* registers when the
> ratio between MDCLK and CDCLK changes. The updates must be done before
> changing the CDCLK when decreasing the frequency; or after it when
> increasing the frequency.
> 
> Ratio-related updates to MBUS_CTL also depend on the state of MBus
> joining, so they are performed by either CDCLK change sequence or by
> changes in MBus joining. Since one might happen independently of the
> other, we need to make sure that both logics see the necessary state
> values when programming that register. MBus joining logic needs to know
> the MDCLK:CDCLK ratio and that's already provided via mdclk_cdclk_ratio
> field of struct intel_dbuf_state.
> 
> For the CDCLK logic, we need to have something similar: we need to
> propagate the status of MBus joining to struct intel_cdclk_state. Do
> that by adding the field joined_mbus to struct intel_cdclk_config.
> (Preferably, that field would be added to intel_cdclk_state, however
> currently only intel_cdclk_config is passed down to the functions that
> do the register programming. We might revisit this decision if we find
> that refactoring the code to pass the whole intel_cdclk_state is worth
> it.)
> 
> Bspec: 68864, 68868, 69090, 69482
> Signed-off-by: Gustavo Sousa <gustavo.sousa@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_cdclk.c    | 31 ++++++++++++++
>  drivers/gpu/drm/i915/display/intel_cdclk.h    |  3 ++
>  drivers/gpu/drm/i915/display/skl_watermark.c  | 40 +++++++++++++++----
>  drivers/gpu/drm/i915/display/skl_watermark.h  |  1 +
>  .../gpu/drm/i915/display/skl_watermark_regs.h | 18 +++++----
>  5 files changed, 77 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.c b/drivers/gpu/drm/i915/display/intel_cdclk.c
> index 04a6e9806254..12753589072d 100644
> --- a/drivers/gpu/drm/i915/display/intel_cdclk.c
> +++ b/drivers/gpu/drm/i915/display/intel_cdclk.c
> @@ -40,6 +40,7 @@
>  #include "intel_psr.h"
>  #include "intel_vdsc.h"
>  #include "skl_watermark.h"
> +#include "skl_watermark_regs.h"
>  #include "vlv_sideband.h"
>  
>  /**
> @@ -1683,6 +1684,8 @@ static void bxt_get_cdclk(struct drm_i915_private *dev_priv,
>  	}
>  
>   out:
> +	if (DISPLAY_VER(dev_priv) >= 20)
> +		cdclk_config->joined_mbus = intel_de_read(dev_priv, MBUS_CTL) & MBUS_JOIN;
>  	/*
>  	 * Can't read this out :( Let's assume it's
>  	 * at least what the CDCLK frequency requires.
> @@ -1908,6 +1911,14 @@ u8 intel_mdclk_cdclk_ratio(struct drm_i915_private *i915,
>  	}
>  }
>  
> +static void xe2lpd_mdclk_cdclk_ratio_program(struct drm_i915_private *i915,
> +					     const struct intel_cdclk_config *cdclk_config)
> +{
> +	intel_dbuf_mdclk_cdclk_ratio_update(i915,
> +					    intel_mdclk_cdclk_ratio(i915, cdclk_config),
> +					    cdclk_config->joined_mbus);
> +}
> +
>  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,
> @@ -2089,6 +2100,9 @@ static void bxt_set_cdclk(struct drm_i915_private *dev_priv,
>  		return;
>  	}
>  
> +	if (DISPLAY_VER(dev_priv) >= 20 && cdclk < dev_priv->display.cdclk.hw.cdclk)
> +		xe2lpd_mdclk_cdclk_ratio_program(dev_priv, cdclk_config);
> +
>  	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);
> @@ -2097,6 +2111,9 @@ static void bxt_set_cdclk(struct drm_i915_private *dev_priv,
>  		_bxt_set_cdclk(dev_priv, cdclk_config, pipe);
>  	}
>  
> +	if (DISPLAY_VER(dev_priv) >= 20 && cdclk > dev_priv->display.cdclk.hw.cdclk)
> +		xe2lpd_mdclk_cdclk_ratio_program(dev_priv, cdclk_config);
> +
>  	if (DISPLAY_VER(dev_priv) >= 14)
>  		/*
>  		 * NOOP - No Pcode communication needed for
> @@ -3179,6 +3196,20 @@ int intel_cdclk_atomic_check(struct intel_atomic_state *state,
>  	return 0;
>  }
>  
> +int intel_cdclk_state_set_joined_mbus(struct intel_atomic_state *state, bool joined_mbus)
> +{
> +	struct intel_cdclk_state *cdclk_state;
> +
> +	cdclk_state = intel_atomic_get_cdclk_state(state);
> +	if (IS_ERR(cdclk_state))
> +		return PTR_ERR(cdclk_state);
> +
> +	cdclk_state->actual.joined_mbus = joined_mbus;
> +	cdclk_state->logical.joined_mbus = joined_mbus;
> +
> +	return intel_atomic_lock_global_state(&cdclk_state->base);

Shouldn't we actually lock global state already before we modify
the cdclk_state?


Stan

> +}
> +
>  int intel_cdclk_init(struct drm_i915_private *dev_priv)
>  {
>  	struct intel_cdclk_state *cdclk_state;
> diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.h b/drivers/gpu/drm/i915/display/intel_cdclk.h
> index 8e6e302bd599..e358234bfe26 100644
> --- a/drivers/gpu/drm/i915/display/intel_cdclk.h
> +++ b/drivers/gpu/drm/i915/display/intel_cdclk.h
> @@ -18,6 +18,8 @@ struct intel_crtc_state;
>  struct intel_cdclk_config {
>  	unsigned int cdclk, vco, ref, bypass;
>  	u8 voltage_level;
> +	/* This field is only valid for Xe2LPD and above. */
> +	bool joined_mbus;
>  };
>  
>  struct intel_cdclk_state {
> @@ -74,6 +76,7 @@ void intel_cdclk_get_cdclk(struct drm_i915_private *dev_priv,
>  			   struct intel_cdclk_config *cdclk_config);
>  int intel_cdclk_atomic_check(struct intel_atomic_state *state,
>  			     bool *need_cdclk_calc);
> +int intel_cdclk_state_set_joined_mbus(struct intel_atomic_state *state, bool joined_mbus);
>  struct intel_cdclk_state *
>  intel_atomic_get_cdclk_state(struct intel_atomic_state *state);
>  
> diff --git a/drivers/gpu/drm/i915/display/skl_watermark.c b/drivers/gpu/drm/i915/display/skl_watermark.c
> index 4410e21888ad..bc341abcab2f 100644
> --- a/drivers/gpu/drm/i915/display/skl_watermark.c
> +++ b/drivers/gpu/drm/i915/display/skl_watermark.c
> @@ -12,6 +12,7 @@
>  #include "intel_atomic.h"
>  #include "intel_atomic_plane.h"
>  #include "intel_bw.h"
> +#include "intel_cdclk.h"
>  #include "intel_crtc.h"
>  #include "intel_de.h"
>  #include "intel_display.h"
> @@ -2601,10 +2602,17 @@ skl_compute_ddb(struct intel_atomic_state *state)
>  			return ret;
>  	}
>  
> -	if (HAS_MBUS_JOINING(i915))
> +	if (HAS_MBUS_JOINING(i915)) {
>  		new_dbuf_state->joined_mbus =
>  			adlp_check_mbus_joined(new_dbuf_state->active_pipes);
>  
> +		if (old_dbuf_state->joined_mbus != new_dbuf_state->joined_mbus) {
> +			ret = intel_cdclk_state_set_joined_mbus(state, new_dbuf_state->joined_mbus);
> +			if (ret)
> +				return ret;
> +		}
> +	}
> +
>  	for_each_intel_crtc(&i915->drm, crtc) {
>  		enum pipe pipe = crtc->pipe;
>  
> @@ -3545,12 +3553,14 @@ int intel_dbuf_state_set_mdclk_cdclk_ratio(struct intel_atomic_state *state, u8
>  	return intel_atomic_lock_global_state(&dbuf_state->base);
>  }
>  
> -static void intel_dbuf_mdclk_cdclk_ratio_update(struct drm_i915_private *i915,
> -						u8 ratio,
> -						bool joined_mbus)
> +void intel_dbuf_mdclk_cdclk_ratio_update(struct drm_i915_private *i915, u8 ratio, bool joined_mbus)
>  {
>  	enum dbuf_slice slice;
>  
> +	if (DISPLAY_VER(i915) >= 20)
> +		intel_de_rmw(i915, MBUS_CTL, MBUS_TRANSLATION_THROTTLE_MIN_MASK,
> +			     MBUS_TRANSLATION_THROTTLE_MIN(ratio - 1));
> +
>  	if (joined_mbus)
>  		ratio *= 2;
>  
> @@ -3568,7 +3578,9 @@ static void update_mbus_pre_enable(struct intel_atomic_state *state)
>  {
>  	struct drm_i915_private *i915 = to_i915(state->base.dev);
>  	u32 mbus_ctl;
> -	const struct intel_dbuf_state *dbuf_state =
> +	const struct intel_dbuf_state *old_dbuf_state =
> +		intel_atomic_get_old_dbuf_state(state);
> +	const struct intel_dbuf_state *new_dbuf_state =
>  		intel_atomic_get_new_dbuf_state(state);
>  
>  	if (!HAS_MBUS_JOINING(i915))
> @@ -3578,7 +3590,7 @@ static void update_mbus_pre_enable(struct intel_atomic_state *state)
>  	 * TODO: Implement vblank synchronized MBUS joining changes.
>  	 * Must be properly coordinated with dbuf reprogramming.
>  	 */
> -	if (dbuf_state->joined_mbus)
> +	if (new_dbuf_state->joined_mbus)
>  		mbus_ctl = MBUS_HASHING_MODE_1x4 | MBUS_JOIN |
>  			MBUS_JOIN_PIPE_SELECT_NONE;
>  	else
> @@ -3589,8 +3601,20 @@ static void update_mbus_pre_enable(struct intel_atomic_state *state)
>  		     MBUS_HASHING_MODE_MASK | MBUS_JOIN |
>  		     MBUS_JOIN_PIPE_SELECT_MASK, mbus_ctl);
>  
> -	intel_dbuf_mdclk_cdclk_ratio_update(i915, dbuf_state->mdclk_cdclk_ratio,
> -					    dbuf_state->joined_mbus);
> +	if (DISPLAY_VER(i915) >= 20 &&
> +	    old_dbuf_state->mdclk_cdclk_ratio != new_dbuf_state->mdclk_cdclk_ratio) {
> +		/*
> +		 * For Xe2LPD and beyond, when there is a change in the ratio
> +		 * between MDCLK and CDCLK, updates to related registers need to
> +		 * happen at a specific point in the CDCLK change sequence. In
> +		 * that case, we defer to the call to
> +		 * intel_dbuf_mdclk_cdclk_ratio_update() to the CDCLK logic.
> +		 */
> +		return;
> +	}
> +
> +	intel_dbuf_mdclk_cdclk_ratio_update(i915, new_dbuf_state->mdclk_cdclk_ratio,
> +					    new_dbuf_state->joined_mbus);
>  }
>  
>  void intel_dbuf_pre_plane_update(struct intel_atomic_state *state)
> diff --git a/drivers/gpu/drm/i915/display/skl_watermark.h b/drivers/gpu/drm/i915/display/skl_watermark.h
> index fed4d12df584..3a90741cab06 100644
> --- a/drivers/gpu/drm/i915/display/skl_watermark.h
> +++ b/drivers/gpu/drm/i915/display/skl_watermark.h
> @@ -76,6 +76,7 @@ int intel_dbuf_state_set_mdclk_cdclk_ratio(struct intel_atomic_state *state, u8
>  
>  void intel_dbuf_pre_plane_update(struct intel_atomic_state *state);
>  void intel_dbuf_post_plane_update(struct intel_atomic_state *state);
> +void intel_dbuf_mdclk_cdclk_ratio_update(struct drm_i915_private *i915, u8 ratio, bool joined_mbus);
>  void intel_mbus_dbox_update(struct intel_atomic_state *state);
>  
>  #endif /* __SKL_WATERMARK_H__ */
> diff --git a/drivers/gpu/drm/i915/display/skl_watermark_regs.h b/drivers/gpu/drm/i915/display/skl_watermark_regs.h
> index 20b30c9a6613..269163fa3350 100644
> --- a/drivers/gpu/drm/i915/display/skl_watermark_regs.h
> +++ b/drivers/gpu/drm/i915/display/skl_watermark_regs.h
> @@ -32,14 +32,16 @@
>  #define MBUS_BBOX_CTL_S1		_MMIO(0x45040)
>  #define MBUS_BBOX_CTL_S2		_MMIO(0x45044)
>  
> -#define MBUS_CTL			_MMIO(0x4438C)
> -#define MBUS_JOIN			REG_BIT(31)
> -#define MBUS_HASHING_MODE_MASK		REG_BIT(30)
> -#define MBUS_HASHING_MODE_2x2		REG_FIELD_PREP(MBUS_HASHING_MODE_MASK, 0)
> -#define MBUS_HASHING_MODE_1x4		REG_FIELD_PREP(MBUS_HASHING_MODE_MASK, 1)
> -#define MBUS_JOIN_PIPE_SELECT_MASK	REG_GENMASK(28, 26)
> -#define MBUS_JOIN_PIPE_SELECT(pipe)	REG_FIELD_PREP(MBUS_JOIN_PIPE_SELECT_MASK, pipe)
> -#define MBUS_JOIN_PIPE_SELECT_NONE	MBUS_JOIN_PIPE_SELECT(7)
> +#define MBUS_CTL				_MMIO(0x4438C)
> +#define   MBUS_JOIN				REG_BIT(31)
> +#define   MBUS_HASHING_MODE_MASK		REG_BIT(30)
> +#define   MBUS_HASHING_MODE_2x2			REG_FIELD_PREP(MBUS_HASHING_MODE_MASK, 0)
> +#define   MBUS_HASHING_MODE_1x4			REG_FIELD_PREP(MBUS_HASHING_MODE_MASK, 1)
> +#define   MBUS_JOIN_PIPE_SELECT_MASK		REG_GENMASK(28, 26)
> +#define   MBUS_JOIN_PIPE_SELECT(pipe)		REG_FIELD_PREP(MBUS_JOIN_PIPE_SELECT_MASK, pipe)
> +#define   MBUS_JOIN_PIPE_SELECT_NONE		MBUS_JOIN_PIPE_SELECT(7)
> +#define   MBUS_TRANSLATION_THROTTLE_MIN_MASK	REG_GENMASK(15, 13)
> +#define   MBUS_TRANSLATION_THROTTLE_MIN(val)	REG_FIELD_PREP(MBUS_TRANSLATION_THROTTLE_MIN_MASK, val)
>  
>  /* Watermark register definitions for SKL */
>  #define _CUR_WM_A_0		0x70140
> -- 
> 2.44.0
>