-----Original Message----- From: Adrian Hunter [mailto:adrian.hunter@xxxxxxxxx] Sent: Friday, June 01, 2018 6:48 PM To: sayali <sayalil@xxxxxxxxxxxxxx>; subhashj@xxxxxxxxxxxxxx; cang@xxxxxxxxxxxxxx; vivek.gautam@xxxxxxxxxxxxxx; rnayak@xxxxxxxxxxxxxx; vinholikatti@xxxxxxxxx; jejb@xxxxxxxxxxxxxxxxxx; martin.petersen@xxxxxxxxxx; asutoshd@xxxxxxxxxxxxxx; evgreen@xxxxxxxxxxxx Cc: linux-scsi@xxxxxxxxxxxxxxx; 'open list' <linux-kernel@xxxxxxxxxxxxxxx> Subject: Re: [PATCH V1 1/3] scsi: ufs: set the device reference clock setting On 01/06/18 16:11, sayali wrote: > Hi Adrain, > > Updated my comments inline. Please check. > > Thanks, > Sayali > -----Original Message----- > From: Adrian Hunter [mailto:adrian.hunter@xxxxxxxxx] > Sent: Friday, June 01, 2018 5:59 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 > Cc: linux-scsi@xxxxxxxxxxxxxxx; open list > <linux-kernel@xxxxxxxxxxxxxxx> > Subject: Re: [PATCH V1 1/3] scsi: ufs: set the device reference clock > setting > > On 01/06/18 13:42, 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> >> [cang@xxxxxxxxxxxxxx: Resolved trivial merge conflicts] >> Signed-off-by: Can Guo <cang@xxxxxxxxxxxxxx> >> Signed-off-by: Sayali Lokhande <sayalil@xxxxxxxxxxxxxx> >> --- >> drivers/scsi/ufs/ufs.h | 9 +++++++ >> drivers/scsi/ufs/ufshcd.c | 62 >> +++++++++++++++++++++++++++++++++++++++++++++++ >> drivers/scsi/ufs/ufshcd.h | 1 + >> 3 files changed, 72 insertions(+) >> >> 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.c b/drivers/scsi/ufs/ufshcd.c >> index c5b1bf1..3669bc4 100644 >> --- a/drivers/scsi/ufs/ufshcd.c >> +++ b/drivers/scsi/ufs/ufshcd.c >> @@ -6297,6 +6297,63 @@ static void ufshcd_def_desc_sizes(struct >> ufs_hba *hba) } >> >> /** >> + * ufshcd_set_dev_ref_clk - set the device bRefClkFreq >> + * @hba: per-adapter instance >> + * @ref_clk_freq: refrerence clock frequency to be set >> + * >> + * 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, u32 >> +ref_clk_freq) { >> + int err = 0; >> + int ref_clk = -1; >> + static const char * const ref_clk_freqs[] = {"19.2 MHz", "26 MHz", >> + "38.4 MHz", "52 MHz"}; >> + >> + hba->dev_ref_clk_freq = ref_clk_freq; >> + 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 < 0) || (ref_clk > REF_CLK_FREQ_52_MHZ)) { > > If you used u32 ref_clk then you wouldn't have to check < 0, also you should use REF_CLK_FREQ_MAX not REF_CLK_FREQ_52_MHZ, but really why is this check needed anyway? > [Sayali] Here ref_clk is defined as integer with value -1. We are then reading bRefClkFreq attribute from device into ref_clk and hence the sanity check is required before we update/write bRefClkFreq attribute. But why sanity check a value that is going to be overwritten? [Sayali] Agreed. I need not check the ref_clk(which is the current setting), but still I should add check for new setting " ref_clk_freq" that is passed and going to be written (like ref_clk_freq < REF_CLK_FREQ_MAX). Will update in next patchset. > >> + dev_err(hba->dev, "%s: invalid ref_clk setting = %d\n", >> + __func__, ref_clk); >> + err = -EINVAL; >> + 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]); >> + else >> + /* >> + * It is good to print this out here to debug any later failures >> + * related to gear switch. >> + */ >> + dev_info(hba->dev, "%s: bRefClkFreq setting to %s succeeded\n", >> + __func__, ref_clk_freqs[hba->dev_ref_clk_freq]); > > Why not make this dev_dbg and print always even when there is no update. > [Sayali] Agreed. Will update in next patchsets. > >> + >> +out: >> + return err; >> +} >> + >> +/** >> * ufshcd_probe_hba - probe hba to detect device and initialize >> * @hba: per-adapter instance >> * >> @@ -6361,6 +6418,11 @@ 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, REF_CLK_FREQ_19_2_MHZ); >> 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 >> > > >
