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

Eric Chanudet
2023-11-29T19:04:43Z

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;
>
> 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 {
> + val = ufshcd_readl(host->hba, REG_UFS_DEBUG_SPARE_CFG);
> + dev_major = FIELD_GET(GENMASK(7, 4), val);
> +
> + /* UFS device version populated, no need to do init twice */

This change documents the content of the register as "UFS device
version", both inline in the code and in the commit description. Earlier
in this series[1], Mani mentioned it was the gear info:
> > [...]populating a spare register in the bootloader with the max gear
> > info that the bootloader has already found[...]

Is it the gear number as in HS-G4? Or the version as in UFS controller
revision 3.1?

[1] https://lore.kernel.org/all/20231018124741.GA47321@thinkpad/

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

--
Eric Chanudet