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Subject: Re: [PATCH V8 1/2] scsi: ufs: set the device reference clock setting
To:     Sayali Lokhande <sayalil@codeaurora.org>, subhashj@codeaurora.org,
        cang@codeaurora.org, vivek.gautam@codeaurora.org,
        rnayak@codeaurora.org, vinholikatti@gmail.com,
        jejb@linux.vnet.ibm.com, martin.petersen@oracle.com,
        asutoshd@codeaurora.org, evgreen@chromium.org,
        riteshh@codeaurora.org
Cc:     linux-scsi@vger.kernel.org,
        open list <linux-kernel@vger.kernel.org>
References: <1533805799-5831-1-git-send-email-sayalil@codeaurora.org>
 <1533805799-5831-2-git-send-email-sayalil@codeaurora.org>
 <4efbbb33-95ec-c631-57d4-ca9898e6d475@intel.com>
 <1756f41e-6280-8a14-bc83-e4dab8fa4d9c@codeaurora.org>
From:   Adrian Hunter <adrian.hunter@intel.com>
Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki,
 Business Identity Code: 0357606 - 4, Domiciled in Helsinki
Message-ID: <5b30fb6c-0cb2-f0be-3df6-918963db6369@intel.com>
Date:   Thu, 16 Aug 2018 14:28:36 +0300
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On 16/08/18 13:44, Sayali Lokhande wrote:
> 
> On 8/13/2018 6:06 PM, Adrian Hunter wrote:
>> On 09/08/18 12:09, Sayali Lokhande 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           | 21 ++++++++++
>>>   drivers/scsi/ufs/ufshcd-pltfrm.c |  2 +
>>>   drivers/scsi/ufs/ufshcd.c        | 89
>>> ++++++++++++++++++++++++++++++++++++++++
>>>   drivers/scsi/ufs/ufshcd.h        |  2 +
>>>   4 files changed, 114 insertions(+)
>>>
>>> diff --git a/drivers/scsi/ufs/ufs.h b/drivers/scsi/ufs/ufs.h
>>> index 14e5bf7..c555ac0 100644
>>> --- a/drivers/scsi/ufs/ufs.h
>>> +++ b/drivers/scsi/ufs/ufs.h
>>> @@ -378,6 +378,27 @@ enum query_opcode {
>>>       UPIU_QUERY_OPCODE_TOGGLE_FLAG    = 0x8,
>>>   };
>>>   +/* bRefClkFreq attribute values */
>>> +enum ref_clk_freq_hz {
>>> +    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,
>>> +};
>>> +
>>> +enum bref_clk_freq {
>>> +    bREF_CLK_FREQ_0, /* 19.2 MHz */
>>> +    bREF_CLK_FREQ_1, /* 26 MHz */
>>> +    bREF_CLK_FREQ_2, /* 38.4 MHz */
>>> +    bREF_CLK_FREQ_3, /* 52 MHz */
>>> +    bREF_CLK_FREQ_INVAL,
>>> +};
>>> +
>>> +struct ufs_ref_clk {
>>> +    enum ref_clk_freq_hz freq_hz;
>>> +    enum bref_clk_freq val;
>>> +};
>>> +
>>>   /* 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..0cbdde7 100644
>>> --- a/drivers/scsi/ufs/ufshcd.c
>>> +++ b/drivers/scsi/ufs/ufshcd.c
>>> @@ -6296,6 +6296,89 @@ 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[] = {
>>> +    {REF_CLK_FREQ_19_2_MHZ, bREF_CLK_FREQ_0},
>>> +    {REF_CLK_FREQ_26_MHZ, bREF_CLK_FREQ_1},
>>> +    {REF_CLK_FREQ_38_4_MHZ, bREF_CLK_FREQ_2},
>>> +    {REF_CLK_FREQ_52_MHZ, bREF_CLK_FREQ_3},
>>> +};
>>> +
>>> +static inline enum bref_clk_freq
>>> +ufs_get_bref_clk_for_ref_clk_freq_hz(u32 freq)
>>> +{
>>> +    enum bref_clk_freq val;
>>> +
>>> +    for (val = bREF_CLK_FREQ_0; val <= bREF_CLK_FREQ_3; val++)
>>> +        if (ufs_ref_clk_freqs[val].freq_hz == freq)
>>> +            return val;
>>> +
>>> +    /* if no match found, return invalid*/
>>> +    return bREF_CLK_FREQ_INVAL;
>>> +}
>>> +
>>> +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 = bREF_CLK_FREQ_INVAL;
>>> +
>>> +    refclk = of_clk_get_by_name(np, "ref_clk");
>> What about users that don't use DT?
> If there is no DT entry present for ref_clk, we simply set to
> bREF_CLK_FREQ_INVAL and thus ref clk will not be changed. It will maintain
> the Manufacturer default value whatever is set by the ufs device vendor.

I meant there is no way for non-DT uses to specify the ref_clk.

>>
>>> +    if (!refclk)
>>> +        return;
>>> +
>>> +    freq = clk_get_rate(refclk);
>>> +    if (freq > REF_CLK_FREQ_52_MHZ) {
>>> +        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;
>>> +    int ref_clk = -1;
>>> +
>>> +    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,
>>> +            &hba->dev_ref_clk_freq);
>>> +
>>> +    if (err)
>>> +        dev_err(hba->dev, "%s: bRefClkFreq setting to %d Hz failed\n",
>>> +        __func__, ufs_ref_clk_freqs[hba->dev_ref_clk_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 %d Hz succeeded\n",
>>> +        __func__, ufs_ref_clk_freqs[hba->dev_ref_clk_freq].freq_hz);
>>> +
>>> +out:
>>> +    return err;
>>> +}
>>> +
>>>   /**
>>>    * ufshcd_probe_hba - probe hba to detect device and initialize
>>>    * @hba: per-adapter instance
>>> @@ -6361,6 +6444,12 @@ 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 < bREF_CLK_FREQ_INVAL)
>> hba->dev_ref_clk_freq does not always get initialized
> In ufshcd_parse_dev_ref_clk_freq() function we are initializing the
> hba->dev_ref_clk_freqto inval as default.

Not if there is no DT

>                                           This parse function will be always
> called in init

Not if the driver isn't ufshcd-pltfrm

>                and thus dev_ref_clk_freq should always get initialized to
> called in init and thus dev_ref_clk_freq should always get initialized to
> defult inval or valid setting if found (in between 19.2 MHz to 52MHz).
>>
>>> +            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;
>>>         /* 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)
>>>   {
>>>
> 
>