Re: [PATCH V9 1/2] scsi: ufs: set the device reference clock setting

From: Sayali Lokhande
Date: Fri Aug 24 2018 - 01:24:39 EST


On 8/23/2018 10:49 PM, Evan Green wrote:
On Tue, Aug 21, 2018 at 3:18 AM Sayali Lokhande <sayalil@xxxxxxxxxxxxxx> wrote:
From: Subhash Jadavani <subhashj@xxxxxxxxxxxxxx>

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.

Signed-off-by: Subhash Jadavani <subhashj@xxxxxxxxxxxxxx>
Signed-off-by: Can Guo <cang@xxxxxxxxxxxxxx>
Signed-off-by: Sayali Lokhande <sayalil@xxxxxxxxxxxxxx>
---
drivers/scsi/ufs/ufs.h | 14 ++++++++
drivers/scsi/ufs/ufshcd.c | 92 +++++++++++++++++++++++++++++++++++++++++++++++
drivers/scsi/ufs/ufshcd.h | 2 ++
3 files changed, 108 insertions(+)

diff --git a/drivers/scsi/ufs/ufs.h b/drivers/scsi/ufs/ufs.h
index 14e5bf7..a2e76b1 100644
--- a/drivers/scsi/ufs/ufs.h
+++ b/drivers/scsi/ufs/ufs.h
@@ -378,6 +378,20 @@ enum query_opcode {
UPIU_QUERY_OPCODE_TOGGLE_FLAG = 0x8,
};

+/* bRefClkFreq attribute values */
+enum ufs_ref_clk_freq {
+ REF_CLK_FREQ_19_2_MHZ = 0,
+ REF_CLK_FREQ_26_MHZ = 1,
+ REF_CLK_FREQ_38_4_MHZ = 2,
+ REF_CLK_FREQ_52_MHZ = 3,
+ REF_CLK_FREQ_INVAL = -1,
+};
+
+struct ufs_ref_clk {
+ u32 freq_hz;
+ enum ufs_ref_clk_freq val;
+};
+
/* Query response result code */
enum {
QUERY_RESULT_SUCCESS = 0x00,
diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index c5b1bf1..e946844 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -6296,6 +6296,91 @@ static void ufshcd_def_desc_sizes(struct ufs_hba *hba)
hba->desc_size.hlth_desc = QUERY_DESC_HEALTH_DEF_SIZE;
}

+static struct ufs_ref_clk ufs_ref_clk_freqs[] = {
+ {19200000, REF_CLK_FREQ_19_2_MHZ},
+ {26000000, REF_CLK_FREQ_26_MHZ},
+ {38400000, REF_CLK_FREQ_38_4_MHZ},
+ {52000000, REF_CLK_FREQ_52_MHZ},
+ {0, REF_CLK_FREQ_INVAL},
+};
+
+static inline enum ufs_ref_clk_freq
+ufs_get_bref_clk_for_ref_clk_freq_hz(u32 freq)
This name is a little hairy. Maybe ufs_get_bref_clk_from_hz, or
ufs_hz_to_bref_clk?
Done. ufs_get_bref_clk_from_hz() sounds good. Will update.
+{
+ int i = 0;
+
+ while (ufs_ref_clk_freqs[i].freq_hz != freq) {
+ if (!ufs_ref_clk_freqs[i].freq_hz)
+ return REF_CLK_FREQ_INVAL;
+ i++;
+ }
+
+ return ufs_ref_clk_freqs[i].val;
+}
+
+void ufshcd_parse_dev_ref_clk_freq(struct ufs_hba *hba)
+{
+ struct device *dev = hba->dev;
+ struct device_node *np = dev->of_node;
+ struct clk *refclk = NULL;
+ u32 freq = 0;
+
+ if (!np)
+ return;
+
+ hba->dev_ref_clk_freq = REF_CLK_FREQ_INVAL;
+
+ refclk = of_clk_get_by_name(np, "ref_clk");
+ if (!refclk)
+ return;
+
+ freq = clk_get_rate(refclk);
+ if (freq > REF_CLK_FREQ_52_MHZ) {
freq is in Hertz, but the enum value will be something like 3. I think
you should just call your function below, and then check the return
value of it for the error case you're trying to do here.
Agree. I should be checking hba->dev_ref_clk_freq instead of freq (which is in hz). Will update.
+ dev_err(hba->dev,
+ "%s: invalid ref_clk setting = %d\n",
+ __func__, freq);
+ return;
+ }
+
+ hba->dev_ref_clk_freq =
+ ufs_get_bref_clk_for_ref_clk_freq_hz(freq);
+}
+
+static int ufshcd_set_dev_ref_clk(struct ufs_hba *hba)
+{
+ int err = 0;
You don't need to initialize this since you immediately assign it below.
Done.
+ int ref_clk = -1;
+ u32 freq = (u32)hba->dev_ref_clk_freq;
Is the cast necessary?
Not necessary. Will be removed.
+
+ 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 == 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, &freq);
+
+ if (err)
+ dev_err(hba->dev, "%s: bRefClkFreq setting to %u Hz failed\n",
+ __func__, ufs_ref_clk_freqs[freq].freq_hz);
+ /*
+ * It is good to print this out here to debug any later failures
+ * related to gear switch.
+ */
+ dev_dbg(hba->dev, "%s: bRefClkFreq setting to %u Hz succeeded\n",
+ __func__, ufs_ref_clk_freqs[freq].freq_hz);
In the error case you print out both the failed message and the success message?
Agree. Will add goto out; in error case above.
+
+out:
+ return err;
+}
+
/**
* ufshcd_probe_hba - probe hba to detect device and initialize
* @hba: per-adapter instance
@@ -6361,6 +6446,12 @@ static int ufshcd_probe_hba(struct ufs_hba *hba)
"%s: Failed getting max supported power mode\n",
__func__);
} else {
+ /*
+ * Set the right value to bRefClkFreq before attempting to
+ * switch to HS gears.
+ */
+ if (hba->dev_ref_clk_freq != REF_CLK_FREQ_INVAL)
+ 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",
@@ -7693,6 +7784,7 @@ int ufshcd_alloc_host(struct device *dev, struct ufs_hba **hba_handle)

INIT_LIST_HEAD(&hba->clk_list_head);

+ ufshcd_parse_dev_ref_clk_freq(hba);
I get an uncomfortable feeling about calling this function from
alloc_host, given that everybody else calls their parse functions from
ufshcd_pltfrm_init. I wonder if you should just initialize the new
member here in alloc_host to the invalid value, and then move the call
to the parse function where you had it before in ufshcd_pltfrm_init.
That way you don't have the problems in the previous series with
leaving the value uninitialized, but you're also not calling of_
functions from alloc_host, which seems like an abuse of alloc_host.
Agree. Will only initialize the ref_clk in alloc_host() and move the actual parse() call in pltfrm_init as before.
-Evan