Re: [PATCH v5 04/10] scsi: ufs: ufs-qcom: Limit negotiated gear to selected PHY gear

Manivannan Sadhasivam
2023-11-28T05:46:10Z

On Thu, Nov 23, 2023 at 12:46:24AM -0800, Can Guo wrote:
> In the dual init scenario, the initial PHY gear is set to HS-G2, and the
> first Power Mode Change (PMC) is meant to find the best matching PHY gear
> for the 2nd init. However, for the first PMC, if the negotiated gear (say
> HS-G4) is higher than the initial PHY gear, we cannot go ahead let PMC to
> the negotiated gear happen, because the programmed UFS PHY settings may not
> support the negotiated gear. Fix it by overwriting the negotiated gear with
> the PHY gear.
>

I don't quite understand this patch. If the phy_gear is G2 initially and the
negotiated gear is G4, then as per this change,

phy_gear = G4;
negotiated gear = G2;

Could you please explain how this make sense?

- Mani

> Signed-off-by: Can Guo <quic_cang@quicinc.com>
> ---
> drivers/ufs/host/ufs-qcom.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c
> index cc0eb37..d4edf58 100644
> --- a/drivers/ufs/host/ufs-qcom.c
> +++ b/drivers/ufs/host/ufs-qcom.c
> @@ -920,8 +920,13 @@ static int ufs_qcom_pwr_change_notify(struct ufs_hba *hba,
> * because, the PHY gear settings are backwards compatible and we only need to
> * change the PHY gear settings while scaling to higher gears.
> */
> - if (dev_req_params->gear_tx > host->phy_gear)
> + if (dev_req_params->gear_tx > host->phy_gear) {
> + u32 old_phy_gear = host->phy_gear;
> +
> host->phy_gear = dev_req_params->gear_tx;
> + dev_req_params->gear_tx = old_phy_gear;
> + dev_req_params->gear_rx = old_phy_gear;
> + }
>
> /* enable the device ref clock before changing to HS mode */
> if (!ufshcd_is_hs_mode(&hba->pwr_info) &&
> --
> 2.7.4
>

--
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