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scsi: ufs: read the device bRefClkFreq attribute

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Device reference clock is a crucial parameter, as
it would fail to work in HS, if its value is different than 19.2 MHz.
This is why we should read its value upon start-up and notify
its value as a debug message.
We don't want to "blindly" configure this attribute as well, as this is
a one-time-programmable parameter and should be considered carefully
before setting it.

Change-Id: Ia2cc0f18fae1189949c30b5b2a65b763c1c46fb1
Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>
This commit is contained in:
Yaniv Gardi 2013-10-30 08:38:16 +02:00 • committed by David Keitel
parent 956d591558
commit 014e61878a
1 changed files with 43 additions and 0 deletions
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43
drivers/scsi/ufs/ufshcd.c
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@ -4413,6 +4413,41 @@ out:
return ret;
}
/**
* ufshcd_get_device_ref_clk - get the device bRefClkFreq
* @hba: per-adapter instance
*
* Returns zero on success, non-zero error value on failure.
*/
static int ufshcd_get_device_ref_clk(struct ufs_hba *hba)
{
int err = 0;
int val = -1;
int retries;
char *arr[] = {"19.2 MHz", "26 MHz", "38.4 MHz", "52 MHz"};
for (retries = QUERY_REQ_RETRIES; retries > 0; retries--) {
/* write attribute */
err = ufshcd_query_attr(hba, UPIU_QUERY_OPCODE_READ_ATTR,
QUERY_ATTR_IDN_REF_CLK_FREQ, 0, 0, &val);
if (!err)
break;
dev_dbg(hba->dev, "%s: failed with error %d\n", __func__, err);
}
if (err || val >= sizeof(arr) || val < 0) {
dev_err(hba->dev, "%s: err = %d, val = %d",
__func__, err, val);
goto out;
}
dev_info(hba->dev, "%s: bRefClkFreq = %s", __func__, arr[val]);
out:
return err;
}
/**
* ufshcd_probe_hba - probe hba to detect device and initialize
* @hba: per-adapter instance
@ -4440,6 +4475,14 @@ static int ufshcd_probe_hba(struct ufs_hba *hba)
if (ret)
goto out;
ret = ufshcd_get_device_ref_clk(hba);
if (ret) {
dev_err(hba->dev,
"%s: Failed reading bRefClkFreq attribute\n",
__func__);
ret = 0;
}
/* UFS device is also active now */
ufshcd_set_ufs_dev_active(hba);
ufshcd_force_reset_auto_bkops(hba);