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SubjectRe: [PATCH V7 1/2] scsi: ufs: set the device reference clock setting
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Hi Evan,

On 8/6/2018 10:56 PM, Evan Green wrote:
> Hi Sayali,
>
> On Wed, Aug 1, 2018 at 1:49 AM Sayali Lokhande <sayalil@codeaurora.org> wrote:
>> From: Subhash Jadavani <subhashj@codeaurora.org>
>>
>> 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@codeaurora.org>
>> Signed-off-by: Can Guo <cang@codeaurora.org>
>> Signed-off-by: Sayali Lokhande <sayalil@codeaurora.org>
>> ---
>> drivers/scsi/ufs/ufs.h | 8 ++++
>> drivers/scsi/ufs/ufshcd-pltfrm.c | 2 +
>> drivers/scsi/ufs/ufshcd.c | 84 ++++++++++++++++++++++++++++++++++++++++
>> drivers/scsi/ufs/ufshcd.h | 2 +
>> 4 files changed, 96 insertions(+)
>>
>> diff --git a/drivers/scsi/ufs/ufs.h b/drivers/scsi/ufs/ufs.h
>> index 14e5bf7..89e0a33 100644
>> --- a/drivers/scsi/ufs/ufs.h
>> +++ b/drivers/scsi/ufs/ufs.h
>> @@ -378,6 +378,14 @@ enum query_opcode {
>> UPIU_QUERY_OPCODE_TOGGLE_FLAG = 0x8,
>> };
>>
>> +/* bRefClkFreq attribute values */
>> +enum ref_clk_freq {
>> + REF_CLK_FREQ_19_2_MHZ = 19200000,
>> + REF_CLK_FREQ_26_MHZ = 26000000,
>> + REF_CLK_FREQ_38_4_MHZ = 38400000,
>> + REF_CLK_FREQ_52_MHZ = 52000000,
>> +};
>> +
>> /* Query response result code */
>> enum {
>> QUERY_RESULT_SUCCESS = 0x00,
>> diff --git a/drivers/scsi/ufs/ufshcd-pltfrm.c b/drivers/scsi/ufs/ufshcd-pltfrm.c
>> index e82bde0..0953563 100644
>> --- a/drivers/scsi/ufs/ufshcd-pltfrm.c
>> +++ b/drivers/scsi/ufs/ufshcd-pltfrm.c
>> @@ -343,6 +343,8 @@ int ufshcd_pltfrm_init(struct platform_device *pdev,
>> pm_runtime_set_active(&pdev->dev);
>> pm_runtime_enable(&pdev->dev);
>>
>> + ufshcd_parse_dev_ref_clk_freq(hba);
>> +
>> ufshcd_init_lanes_per_dir(hba);
>>
>> err = ufshcd_init(hba, mmio_base, irq);
>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>> index c5b1bf1..619313b 100644
>> --- a/drivers/scsi/ufs/ufshcd.c
>> +++ b/drivers/scsi/ufs/ufshcd.c
>> @@ -6296,6 +6296,84 @@ static void ufshcd_def_desc_sizes(struct ufs_hba *hba)
>> hba->desc_size.hlth_desc = QUERY_DESC_HEALTH_DEF_SIZE;
>> }
>>
>> +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;
>> +
>> + if (!np)
>> + return;
>> +
>> + refclk = of_clk_get_by_name(np, "ref_clk");
>> + if (refclk)
>> + hba->dev_ref_clk_freq = clk_get_rate(refclk);
>> + else if (!refclk ||
>> + (hba->dev_ref_clk_freq > REF_CLK_FREQ_52_MHZ)) {
> What is this logic? The !refclk condition will always be true since
> you're in the else case of if (refclk). Also, even if the second part
> were executed somehow, you haven't assigned dev_ref_clk_freq yet, so
> how can its value be anything other than 0? Maybe that whole
> conditional was just not supposed to be an "else" at all, but a
> standalone if?
Agree. Will update.
>> + dev_err(hba->dev,
>> + "%s: invalid ref_clk setting = %u\n",
>> + __func__, hba->dev_ref_clk_freq);
> There's probably no need to complain if the clock simply couldn't be
> found, only if an unexpected value was found.
Agree. Will update.
>> + hba->dev_ref_clk_freq = 0;
>> + }
>> +}
>> +
>> +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;
>> + }
>> +
>> + switch (hba->dev_ref_clk_freq) {
>> + case REF_CLK_FREQ_19_2_MHZ:
>> + hba->dev_ref_clk_freq = 0x0;
>> + break;
>> + case REF_CLK_FREQ_26_MHZ:
>> + hba->dev_ref_clk_freq = 0x1;
>> + break;
>> + case REF_CLK_FREQ_38_4_MHZ:
>> + hba->dev_ref_clk_freq = 0x2;
>> + break;
>> + case REF_CLK_FREQ_52_MHZ:
>> + hba->dev_ref_clk_freq = 0x3;
>> + break;
>> + default:
>> + dev_err(hba->dev,
>> + "%s: invalid ref_clk setting = %u\n",
>> + __func__, hba->dev_ref_clk_freq);
>> + goto out;
>> + }
> Please don't assign two different things (frequency in Hertz and
> bref_clk value) into the same structure member.
>
> I think rather than having this switch statement you should iterate
> through a table that contains elements of {freq_hz, bref_clk, string}.
> I think you should do this up in ufshcd_parse_dev_ref_clk_freq so that
> you don't have to redo that calculation on every rescan. Then store
> the final bRefClkFreq value (or -1 if no definitive answer could be
> reached) in your new structure member. Then all this function does is
> 1) Nothing if dev_ref_clk_freq is -1, or 2) read and maybe write the
> attribute.
Agree. Will update.
>> +
>> + 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]);
>> + /*
>> + * 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 %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
>> @@ -6361,6 +6439,12 @@ 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)
>> + 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",
>> diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
>> index 8110dcd..101a75c 100644
>> --- a/drivers/scsi/ufs/ufshcd.h
>> +++ b/drivers/scsi/ufs/ufshcd.h
>> @@ -548,6 +548,7 @@ struct ufs_hba {
>> void *priv;
>> unsigned int irq;
>> bool is_irq_enabled;
>> + u32 dev_ref_clk_freq;
> If you followed my suggestion of this storing _only_ the bRefClkFreq
> value or -1 if unset, then this would need to be signed, and
> initialized somewhere so that 0 wasn't accidentally taken to be a
> parsed value.
Will check and update (if necessary).
>> /* Interrupt aggregation support is broken */
>> #define UFSHCD_QUIRK_BROKEN_INTR_AGGR 0x1
>> @@ -746,6 +747,7 @@ static inline void ufshcd_rmwl(struct ufs_hba *hba, u32 mask, u32 val, u32 reg)
>> int ufshcd_wait_for_register(struct ufs_hba *hba, u32 reg, u32 mask,
>> u32 val, unsigned long interval_us,
>> unsigned long timeout_ms, bool can_sleep);
>> +void ufshcd_parse_dev_ref_clk_freq(struct ufs_hba *hba);
>>
>> static inline void check_upiu_size(void)
>> {
>> --
>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
>> a Linux Foundation Collaborative Project
>>

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