Re: [PATCH V3 1/3] scsi: ufs: set the device reference clock setting

From: Adrian Hunter
Date: Thu Jun 21 2018 - 05:21:10 EST

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In reply to: sayali: "RE: [PATCH V3 1/3] scsi: ufs: set the device reference clock setting"
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On 21/06/18 12:11, sayali wrote:
> Hi Adrian,
>
> Please check my comment inline.
>
> Thanks,
> Sayali
> -----Original Message-----
> From: Adrian Hunter [mailto:adrian.hunter@xxxxxxxxx]
> Sent: Wednesday, June 20, 2018 12:56 PM
> To: Sayali Lokhande <sayalil@xxxxxxxxxxxxxx>; subhashj@xxxxxxxxxxxxxx; cang@xxxxxxxxxxxxxx; vivek.gautam@xxxxxxxxxxxxxx; rnayak@xxxxxxxxxxxxxx; vinholikatti@xxxxxxxxx; jejb@xxxxxxxxxxxxxxxxxx; martin.petersen@xxxxxxxxxx; asutoshd@xxxxxxxxxxxxxx; evgreen@xxxxxxxxxxxx; riteshh@xxxxxxxxxxxxxx
> Cc: linux-scsi@xxxxxxxxxxxxxxx; Rob Herring <robh+dt@xxxxxxxxxx>; Mark Rutland <mark.rutland@xxxxxxx>; Mathieu Malaterre <malat@xxxxxxxxxx>; open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS <devicetree@xxxxxxxxxxxxxxx>; open list <linux-kernel@xxxxxxxxxxxxxxx>
> Subject: Re: [PATCH V3 1/3] scsi: ufs: set the device reference clock setting
>
> On 14/06/18 16:03, Sayali Lokhande 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>
>
> I have repeated my V2 comments below. Please address these when you post V4. Also please provide a change log for each patch version.
>
>> ---
>> .../devicetree/bindings/ufs/ufshcd-pltfrm.txt | 7 +++
>> drivers/scsi/ufs/ufs.h | 9 ++++
>> drivers/scsi/ufs/ufshcd-pltfrm.c | 24 ++++++++++
>> drivers/scsi/ufs/ufshcd.c | 52 ++++++++++++++++++++++
>> drivers/scsi/ufs/ufshcd.h | 1 +
>> 5 files changed, 93 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt
>> b/Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt
>> index c39dfef..4522434 100644
>> --- a/Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt
>> +++ b/Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt
>> @@ -41,6 +41,12 @@ Optional properties:
>> -lanes-per-direction : number of lanes available per direction - either 1 or 2.
>> Note that it is assume same number of lanes is used both
>> directions at once. If not specified, default is 2 lanes per direction.
>> +- dev-ref-clk-freq : Specify the device reference clock frequency, must be one of the following:
>> + 0: 19.2 MHz
>> + 1: 26 MHz
>> + 2: 38.4 MHz
>> + 3: 52 MHz
>> + Defaults to 26 MHz if not specified.
>>
>> Note: If above properties are not defined it can be assumed that the
>> supply regulators or clocks are always on.
>> @@ -66,4 +72,5 @@ Example:
>> freq-table-hz = <100000000 200000000>, <0 0>, <0 0>;
>> phys = <&ufsphy1>;
>> phy-names = "ufsphy";
>> + dev-ref-clk-freq = <0>; /* reference clock freq: 19.2 MHz */
>> };
>> diff --git a/drivers/scsi/ufs/ufs.h b/drivers/scsi/ufs/ufs.h index
>> 14e5bf7..e15deb0 100644
>> --- a/drivers/scsi/ufs/ufs.h
>> +++ b/drivers/scsi/ufs/ufs.h
>> @@ -378,6 +378,15 @@ enum query_opcode {
>> UPIU_QUERY_OPCODE_TOGGLE_FLAG = 0x8,
>> };
>>
>> +/* bRefClkFreq attribute values */
>> +enum ref_clk_freq {
>> + REF_CLK_FREQ_19_2_MHZ = 0x0,
>> + REF_CLK_FREQ_26_MHZ = 0x1,
>> + REF_CLK_FREQ_38_4_MHZ = 0x2,
>> + REF_CLK_FREQ_52_MHZ = 0x3,
>> + REF_CLK_FREQ_MAX = REF_CLK_FREQ_52_MHZ,
>> +};
>> +
>> /* 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..6c877f3 100644
>> --- a/drivers/scsi/ufs/ufshcd-pltfrm.c
>> +++ b/drivers/scsi/ufs/ufshcd-pltfrm.c
>> @@ -221,6 +221,28 @@ static int ufshcd_parse_regulator_info(struct ufs_hba *hba)
>> return err;
>> }
>>
>> +static void ufshcd_parse_dev_ref_clk_freq(struct ufs_hba *hba) {
>> + struct device *dev = hba->dev;
>> + struct device_node *np = dev->of_node;
>> + int ret;
>> +
>> + if (!np)
>> + return;
>> +
>> + ret = of_property_read_u32(np, "dev-ref-clk-freq",
>> + &hba->dev_ref_clk_freq);
>
> This setting is useful for any UFSHC driver. Please move it to ufshcd.c and use device_property_read_u32().
> [Sayali]: Ok. Will update this in next patch set.
>
>> + if (ret ||
>> + (hba->dev_ref_clk_freq < 0) ||
>
> u32 cannot be < 0
> [Sayali]: Will remove this check.
>
>> + (hba->dev_ref_clk_freq > REF_CLK_FREQ_52_MHZ)) {
>> + dev_err(hba->dev,
>> + "%s: invalid ref_clk setting = %d, set to default\n",
>> + __func__, hba->dev_ref_clk_freq);
>> + /* default setting */
>> + hba->dev_ref_clk_freq = REF_CLK_FREQ_26_MHZ;
>
> No, the default must be to leave the value unchanged.
> [Sayali]: As per UFS device specification , bRefClkFreq attribute's default value corresponds to 26 MHz (Manufacturer Default Value). Thus we should set it to default (26MHz) if it's not already set.

No, bRefClkFreq is not volatile and a different value may have already been
programmed to the device. You must not overwrite it if there is no
property. Also writing 26MHz when the property value is invalid makes no sense.

>
>> + }
>> +}
>> +
>> #ifdef CONFIG_PM
>> /**
>> * ufshcd_pltfrm_suspend - suspend power management function @@
>> -343,6 +365,8 @@ 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..4abc7ae 100644
>> --- a/drivers/scsi/ufs/ufshcd.c
>> +++ b/drivers/scsi/ufs/ufshcd.c
>> @@ -6297,6 +6297,53 @@ static void ufshcd_def_desc_sizes(struct
>> ufs_hba *hba) }
>>
>> /**
>> + * ufshcd_set_dev_ref_clk - set the device bRefClkFreq
>> + * @hba: per-adapter instance
>> + *
>> + * Read the current value of the bRefClkFreq attribute from device
>> +and update it
>> + * if host is supplying different reference clock frequency than one
>> +mentioned
>> + * in bRefClkFreq attribute.
>> + *
>> + * Returns zero on success, non-zero error value on failure.
>> + */
>> +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;
>> + }
>> +
>> + 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 +6408,11 @@ 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.
>> + */
>> + 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..b026ad8 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
>>
>
>
>

Next message: Wei Xu: "Re: KVM guest sometimes failed to boot because of kernel stack overflow if KPTI is enabled on a hisilicon ARM64 platform."
Previous message: Jon Hunter: "Re: [PATCH v2 6/8] serial: Add Tegra Combined UART driver"
In reply to: sayali: "RE: [PATCH V3 1/3] scsi: ufs: set the device reference clock setting"
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