Hi Stephen/Adrian,
On 11/15/2016 1:07 AM, Stephen Boyd wrote:
On 11/14, Ritesh Harjani wrote:
@@ -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 ?
+}
+
+/* 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.
+ 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.
+ }
+ 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;
+ 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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