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Date: Thu, 23 Aug 2018 10:19:11 -0700
From: Evan Green <evgreen@...omium.org>
To: sayalil@...eaurora.org
Cc: subhashj@...eaurora.org, cang@...eaurora.org,
vivek.gautam@...eaurora.org,
Rajendra Nayak <rnayak@...eaurora.org>,
Vinayak Holikatti <vinholikatti@...il.com>,
jejb@...ux.vnet.ibm.com, martin.petersen@...cle.com,
asutoshd@...eaurora.org, riteshh@...eaurora.org,
adrian.hunter@...el.com, linux-scsi@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH V9 1/2] scsi: ufs: set the device reference clock setting
On Tue, Aug 21, 2018 at 3:18 AM Sayali Lokhande <sayalil@...eaurora.org> wrote:
>
> From: Subhash Jadavani <subhashj@...eaurora.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@...eaurora.org>
> Signed-off-by: Can Guo <cang@...eaurora.org>
> Signed-off-by: Sayali Lokhande <sayalil@...eaurora.org>
> ---
> 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?
> +{
> + 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.
> + 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.
> + int ref_clk = -1;
> + u32 freq = (u32)hba->dev_ref_clk_freq;
Is the cast necessary?
> +
> + 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?
> +
> +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.
-Evan
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