Re: [PATCH v3 2/3] mmc: dw_mmc-rockchip: Add v2 tuning support

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Hi Detlev

在 2024/8/15 6:34, Detlev Casanova 写道:
From: Shawn Lin <shawn.lin@xxxxxxxxxxxxxx>

v2 tuning will inherit pre-stage loader's phase settings for the first
time, and do re-tune if necessary.
Re-tune will still try the rough degrees, for instance, 90, 180, 270,
360 but continue to do the fine tuning if sample window isn't good
enough.

Signed-off-by: Shawn Lin <shawn.lin@xxxxxxxxxxxxxx>
Signed-off-by: Detlev Casanova <detlev.casanova@xxxxxxxxxxxxx>
---
  drivers/mmc/host/dw_mmc-rockchip.c | 49 ++++++++++++++++++++++++++++++
  1 file changed, 49 insertions(+)

diff --git a/drivers/mmc/host/dw_mmc-rockchip.c b/drivers/mmc/host/dw_mmc-rockchip.c
index b07190ba4b7ac..367633f4e8892 100644
--- a/drivers/mmc/host/dw_mmc-rockchip.c
+++ b/drivers/mmc/host/dw_mmc-rockchip.c
@@ -24,6 +24,8 @@ struct dw_mci_rockchip_priv_data {
  	struct clk		*sample_clk;
  	int			default_sample_phase;
  	int			num_phases;
+	bool			use_v2_tuning;
+	int			last_degree;
  };
static void dw_mci_rk3288_set_ios(struct dw_mci *host, struct mmc_ios *ios)
@@ -134,6 +136,42 @@ static void dw_mci_rk3288_set_ios(struct dw_mci *host, struct mmc_ios *ios)
  #define TUNING_ITERATION_TO_PHASE(i, num_phases) \
  		(DIV_ROUND_UP((i) * 360, num_phases))
+static int dw_mci_v2_execute_tuning(struct dw_mci_slot *slot, u32 opcode)
+{
+	struct dw_mci *host = slot->host;
+	struct dw_mci_rockchip_priv_data *priv = host->priv;
+	struct mmc_host *mmc = slot->mmc;
+	u32 degrees[4] = {90, 180, 270, 360};
+	int i;
+	static bool inherit = true;
+
+	if (inherit) {
+		inherit = false;
+		i = clk_get_phase(priv->sample_clk) / 90 - 1;
+		goto done;
+	}
+
+	/* v2 only support 4 degrees in theory */
+	for (i = 0; i < ARRAY_SIZE(degrees); i++) {
+		if (degrees[i] == priv->last_degree)
+			continue;
+
+		clk_set_phase(priv->sample_clk, degrees[i]);
+		if (!mmc_send_tuning(mmc, opcode, NULL))
+			break;
+	}
+
+	if (i == ARRAY_SIZE(degrees)) {
+		dev_warn(host->dev, "All phases bad!");
+		return -EIO;
+	}
+
+done:
+	dev_info(host->dev, "Successfully tuned phase to %d\n", degrees[i]);
+	priv->last_degree = degrees[i];
+	return 0;
+}
+
  static int dw_mci_rk3288_execute_tuning(struct dw_mci_slot *slot, u32 opcode)
  {
  	struct dw_mci *host = slot->host;
@@ -157,6 +195,13 @@ static int dw_mci_rk3288_execute_tuning(struct dw_mci_slot *slot, u32 opcode)
  		return -EIO;
  	}
+ if (priv->use_v2_tuning) {
+		ret = dw_mci_v2_execute_tuning(slot, opcode);
+		if (!ret)
+			return 0;
+		/* Otherwise we continue using fine tuning */
+	}
+
  	ranges = kmalloc_array(priv->num_phases / 2 + 1,
  			       sizeof(*ranges), GFP_KERNEL);
  	if (!ranges)
@@ -277,6 +322,10 @@ static int dw_mci_rk3288_parse_dt(struct dw_mci *host)
  					&priv->default_sample_phase))
  		priv->default_sample_phase = 0;
+ priv->use_v2_tuning =
+		of_device_is_compatible(host->dev->of_node,
+					"rockchip,rk3576-dw-mshc");
+

v2 is a kind of software decision instead of hardware dependency.
So in theory, any SoC can claim to use it via DT.

  	priv->drv_clk = devm_clk_get(host->dev, "ciu-drive");
  	if (IS_ERR(priv->drv_clk))
  		dev_dbg(host->dev, "ciu-drive not available\n");




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