Messages in this thread | | | Date | Thu, 9 Nov 2023 12:07:37 +0800 | Subject | Re: [PATCH v2 3/7] scsi: ufs: ufs-qcom: Allow the first init start with the maximum supported gear | From | Can Guo <> |
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Hi Mani,
On 11/9/2023 11:47 AM, Manivannan Sadhasivam wrote: > On Wed, Nov 08, 2023 at 04:21:52PM +0800, Can Guo wrote: >> Hi Mani, >> >> On 11/8/2023 1:23 PM, Manivannan Sadhasivam wrote: >>> On Mon, Nov 06, 2023 at 08:46:09PM -0800, Can Guo wrote: >>>> From: Can Guo <quic_cang@quicinc.com> >>>> >>>> During host driver init, the phy_gear is set to the minimum supported gear >>>> (HS_G2). Then, during the first power mode change, the negotiated gear, say >>>> HS-G4, is updated to the phy_gear variable so that in the second init the >>>> updated phy_gear can be used to program the PHY. >>>> >>>> But the current code only allows update the phy_gear to a higher value. If >>>> one wants to start the first init with the maximum support gear, say HS-G4, >>>> the phy_gear is not updated to HS-G3 if the device only supports HS-G3. >>>> >>> >>> Can you elaborate when this can happen? AFAICS, there are 3 possibilities of >>> initial phy gear with this series: >>> >>> 1. If ufshc is < 5.0, then G2 will be used. >>> 2. If ufshc is >= 5.0 and if the version is populated in register, then that >>> gear will be used. Most likely that gear can be G4/G5 depending on the device >>> connected. >>> 3. If ufshc is >=5.0 and version is not populated, then G4 will be used. >>> >>> In all the above cases, I do not see any necessity to switch the phy gear >>> setting to lower one while scaling. Since the gears are backwards compatible, >>> we always use one phy gear sequence. Moreover, we only have 2 init sequences. >>> >>> Please correct me if I'm missing anything. >>> >>> - Mani >> In the next patch, I am setting the initial PHY gear to max HS gear read >> from UFS host cap register, so that we don't need to keep updating the >> initial value for host->phy_gear for different HW versions in future. FYI, >> for HW ver 5 and 6, it is HS-G5. In future, the max gear might become HS-G6 >> or higher on newer HW verions. >> >> I the case #3, if HS-G5 is set to host->phy_gear, the first init uses HS-G5, >> then after negotiation if the agreed gear is HS-G4, we need to update >> host->phy_gear to HS-G4 (a lower value) such that we use a power saving PHY >> gear settings during the 2nd init. >> >> If the commit message is making you confused, I can update it in next >> version. Please let me if I made any mistakes here. >> > > I see redundancy while setting the phy_gear and it is leading to confusion. > In ufs_qcom_set_host_params(), first you are setting phy_gear based on > ufs_qcom_get_hs_gear(), then changing it again with the version check for v5. > > I don't see a necessity for "host->phy_gear = host_params->hs_tx_gear", since in > the later check, you are covering both version <5 and >=5. In the case of HW version >= 5, we are only overwriting the PHY gear only if the UFS device cannot support HS-G5. Hence, we need to give host->phy_gear an initial value.
> > Btw, it would be better to move this logic to a separate function like > ufs_qcom_get_phy_gear() to align with ufs_qcom_get_hs_gear(). > OK, will do in next version.
Thanks, Can Guo. > - Mani > >> Thanks, >> Can Guo. >
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