Hi Stephen/Adrian,

On 11/15/2016 1:07 AM, Stephen Boyd wrote:

On 11/14, Ritesh Harjani wrote:

quoted

@@ -577,6 +578,90 @@ static unsigned int sdhci_msm_get_min_clock(struct sdhci_host *host)
 	return SDHCI_MSM_MIN_CLOCK;
 }

+/**
+ * __sdhci_msm_set_clock - sdhci_msm clock control.
+ *
+ * Description:
+ * Implement MSM version of sdhci_set_clock.
+ * This is required since MSM controller does not
+ * use internal divider and instead directly control
+ * the GCC clock as per HW recommendation.
+ **/
+void __sdhci_msm_set_clock(struct sdhci_host *host, unsigned int clock)
+{
+	u16 clk;
+	unsigned long timeout;
+
+	/*
+	 * Keep actual_clock as zero -
+	 * - since there is no divider used so no need of having actual_clock.
+	 * - MSM controller uses SDCLK for data timeout calculation. If
+	 *   actual_clock is zero, host->clock is taken for calculation.
+	 */
+	host->mmc->actual_clock = 0;
+
+	sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL);
+
+	if (clock == 0)
+		return;
+
+	/*
+	 * MSM controller do not use clock divider.
+	 * Thus read SDHCI_CLOCK_CONTROL and only enable
+	 * clock with no divider value programmed.
+	 */
+	clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
+
+	clk |= SDHCI_CLOCK_INT_EN;
+	sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
+
+	/* Wait max 20 ms */
+	timeout = 20;
+	while (!((clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL))
+		& SDHCI_CLOCK_INT_STABLE)) {
+		if (timeout == 0) {
+			pr_err("%s: Internal clock never stabilised\n",
+			       mmc_hostname(host->mmc));
+			return;
+		}
+		timeout--;
+		mdelay(1);
+	}
+
+	clk |= SDHCI_CLOCK_CARD_EN;
+	sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);

This is almost a copy/paste of sdhci_set_clock(). Can we make
sdhci_set_clock() call a __sdhci_set_clock() function that takes
unsigned int clock, and also a flag indicating if we want to set
the internal clock divider or not? Then we can call
__sdhci_set_clock() from sdhci_set_clock() with (clock, true) as
arguments and (clock, false).

Adrian,
Could you please comment here ?

quoted

+}
+
+/* sdhci_msm_set_clock - Called with (host->lock) spinlock held. */
+static void sdhci_msm_set_clock(struct sdhci_host *host, unsigned int clock)
+{
+	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+	struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host);
+	int rc;
+
+	if (!clock) {
+		msm_host->clk_rate = clock;
+		goto out;
+	}
+
+	spin_unlock_irq(&host->lock);
+	if (clock != msm_host->clk_rate) {

Why do we need to check here? Can't we call clk_set_rate()
Unconditionally?

Since it may so happen that above layers may call for ->set_clock
function with same requested clock more than once, hence we cache the 
host->clock here.
Also, since requested clock (host->clock) can be say 400Mhz but the 
actual pltfm supported clock would be say 384MHz.

quoted

+		rc = clk_set_rate(msm_host->clk, clock);
+		if (rc) {
+			pr_err("%s: Failed to set clock at rate %u\n",
+			       mmc_hostname(host->mmc), clock);
+			spin_lock_irq(&host->lock);
+			goto out;

Or replace the above two lines with goto err;

Ok, I will have another label out_lock instead of err.

quoted

+		}
+		msm_host->clk_rate = clock;
+		pr_debug("%s: Setting clock at rate %lu\n",
+			 mmc_hostname(host->mmc), clk_get_rate(msm_host->clk));
+	}

And put an err label here.

will put the label here as out_lock;

quoted

+	spin_lock_irq(&host->lock);
+out:
+	__sdhci_msm_set_clock(host, clock);
+}
+
 static const struct of_device_id sdhci_msm_dt_match[] = {
 	{ .compatible = "qcom,sdhci-msm-v4" },
 	{},

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