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Commit c87a002d authored by Yaniv Gardi's avatar Yaniv Gardi
Browse files

scsi: ufs: read the device bRefClkFreq attribute 



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: default avatarYaniv Gardi <ygardi@codeaurora.org>
parent 0ebc9c40

drivers/scsi/ufs/ufshcd.c

+43 −0
Original line number Diff line number Diff line
@@ -3768,6 +3768,41 @@ static void ufshcd_init_icc_levels(struct ufs_hba *hba) 
			__func__, icc_level , 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
@@ -3793,6 +3828,14 @@ 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);