scsi: ufs: set the device reference clock setting
UFS host supplies the reference clock to UFS device and UFS device
specification allows host to provide one of the 4 frequencies (19.2 MHz,
26 MHz, 38.4 MHz, 52 MHz) for reference clock. Host should set the
device reference clock frequency setting in the device based on what
frequency it is supplying to UFS device.
Change-Id: Idc544aa0ad29a9c3df8cd6caf6883e44f8685974
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 68c6de8..e0ac4a3 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -6841,6 +6841,61 @@
}
/**
+ * ufshcd_set_dev_ref_clk - set the device bRefClkFreq
+ * @hba: per-adapter instance
+ *
+ * Read the current value of the bRefClkFreq attribute from device and update it
+ * if host is supplying different reference clock frequency than one mentioned
+ * in bRefClkFreq attribute.
+ *
+ * Returns zero on success, non-zero error value on failure.
+ */
+static int ufshcd_set_dev_ref_clk(struct ufs_hba *hba)
+{
+ int err = 0;
+ int ref_clk = -1;
+ static const char * const ref_clk_freqs[] = {"19.2 MHz", "26 MHz",
+ "38.4 MHz", "52 MHz"};
+
+ err = ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_READ_ATTR,
+ QUERY_ATTR_IDN_REF_CLK_FREQ, 0, 0, &ref_clk);
+
+ if (err) {
+ dev_err(hba->dev, "%s: failed reading bRefClkFreq. err = %d\n",
+ __func__, err);
+ goto out;
+ }
+
+ if ((ref_clk < 0) || (ref_clk > REF_CLK_FREQ_52_MHZ)) {
+ dev_err(hba->dev, "%s: invalid ref_clk setting = %d\n",
+ __func__, ref_clk);
+ err = -EINVAL;
+ goto out;
+ }
+
+ if (ref_clk == hba->dev_ref_clk_freq)
+ goto out; /* nothing to update */
+
+ err = ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_WRITE_ATTR,
+ QUERY_ATTR_IDN_REF_CLK_FREQ, 0, 0,
+ &hba->dev_ref_clk_freq);
+
+ if (err)
+ dev_err(hba->dev, "%s: bRefClkFreq setting to %s failed\n",
+ __func__, ref_clk_freqs[hba->dev_ref_clk_freq]);
+ else
+ /*
+ * It is good to print this out here to debug any later failures
+ * related to gear switch.
+ */
+ dev_info(hba->dev, "%s: bRefClkFreq setting to %s succeeded\n",
+ __func__, ref_clk_freqs[hba->dev_ref_clk_freq]);
+
+out:
+ return err;
+}
+
+/**
* ufshcd_probe_hba - probe hba to detect device and initialize
* @hba: per-adapter instance
*
@@ -6896,6 +6951,11 @@
"%s: Failed getting max supported power mode\n",
__func__);
} else {
+ /*
+ * Set the right value to bRefClkFreq before attempting to
+ * switch to HS gears.
+ */
+ ufshcd_set_dev_ref_clk(hba);
ret = ufshcd_config_pwr_mode(hba, &hba->max_pwr_info.info);
if (ret) {
dev_err(hba->dev, "%s: Failed setting power mode, err = %d\n",