Re: [PATCH v6 10/10] scsi: ufs: ufs-qcom: Add support for UFS device version detection

Can Guo
2023-11-30T08:22:02Z

On 11/30/2023 3:25 PM, Manivannan Sadhasivam wrote:
> On Wed, Nov 29, 2023 at 12:28:35AM -0800, Can Guo wrote:
>> From: "Bao D. Nguyen" <quic_nguyenb@quicinc.com>
>>
>> A spare register in UFS host controller is used to indicate the UFS device
>> version. The spare register is populated by bootloader for now, but in
>> future it will be populated by HW automatically during link startup with
>> its best efforts in any boot stages prior to Linux.
>>
>> During host driver init, read the spare register, if it is not populated
>> with a UFS device version, go ahead with the dual init mechanism. If a UFS
>> device version is in there, use the UFS device version together with host
>> controller's HW version to decide the proper PHY gear which should be used
>> to configure the UFS PHY without going through the second init.
>>
>> Signed-off-by: Bao D. Nguyen <quic_nguyenb@quicinc.com>
>> Signed-off-by: Can Guo <quic_cang@quicinc.com>
>> ---
>> drivers/ufs/host/ufs-qcom.c | 23 ++++++++++++++++++-----
>> drivers/ufs/host/ufs-qcom.h | 2 ++
>> 2 files changed, 20 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c
>> index 9c0ebbc..e94dea2 100644
>> --- a/drivers/ufs/host/ufs-qcom.c
>> +++ b/drivers/ufs/host/ufs-qcom.c
>> @@ -1068,15 +1068,28 @@ static void ufs_qcom_advertise_quirks(struct ufs_hba *hba)
>> static void ufs_qcom_set_phy_gear(struct ufs_qcom_host *host)
>> {
>> struct ufs_host_params *host_params = &host->host_params;
>> + u32 val, dev_major = 0;
>
> No need to initialize dev_major.

True.

>
>>
>> host->phy_gear = host_params->hs_tx_gear;
>>
>> - /*
>> - * Power up the PHY using the minimum supported gear (UFS_HS_G2).
>> - * Switching to max gear will be performed during reinit if supported.
>> - */
>> - if (host->hw_ver.major < 0x4)
>> + if (host->hw_ver.major < 0x4) {
>> + /*
>> + * Power up the PHY using the minimum supported gear (UFS_HS_G2).
>> + * Switching to max gear will be performed during reinit if supported.
>> + */
>> host->phy_gear = UFS_HS_G2;
>> + } else {
>
> Can you please add a comment here to describe what is happening?

Will do.

>
>> + val = ufshcd_readl(host->hba, REG_UFS_DEBUG_SPARE_CFG);
>> + dev_major = FIELD_GET(GENMASK(7, 4), val);
>
> It'd be good to add a macro for GENMASK().

OK

>
>> +
>> + /* UFS device version populated, no need to do init twice */
>
> "Since the UFS device version is populated, let's remove the REINIT quirk as the
> negotiated gear won't change during boot. So there is no need to do reinit."
>

Nice comment.

>> + if (dev_major != 0)
>
> 0x0

Done

>
>> + host->hba->quirks &= ~UFSHCD_QUIRK_REINIT_AFTER_MAX_GEAR_SWITCH;
>> +
>> + /* For UFS 3.1 and older, apply HS-G4 PHY gear to save power */
>> + if (dev_major < 0x4 && dev_major > 0)
>
> if (dev_major > 0x0 && dev_major < 0x4)
>

Sure.

Thanks,
Can Guo.

> - Mani
>
>> + host->phy_gear = UFS_HS_G4;
>> + }
>> }
>>
>> static void ufs_qcom_set_host_params(struct ufs_hba *hba)
>> diff --git a/drivers/ufs/host/ufs-qcom.h b/drivers/ufs/host/ufs-qcom.h
>> index 11419eb..d12fc5a 100644
>> --- a/drivers/ufs/host/ufs-qcom.h
>> +++ b/drivers/ufs/host/ufs-qcom.h
>> @@ -54,6 +54,8 @@ enum {
>> UFS_AH8_CFG = 0xFC,
>>
>> REG_UFS_CFG3 = 0x271C,
>> +
>> + REG_UFS_DEBUG_SPARE_CFG = 0x284C,
>> };
>>
>> /* QCOM UFS host controller vendor specific debug registers */
>> --
>> 2.7.4
>>
>>
>