linux-kernel - Re: [PATCH v6 04/10] scsi: ufs: ufs-qcom: Allow the first init start with the maximum supported gear

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Date:   Thu, 30 Nov 2023 15:44:09 +0800
From:   Can Guo <quic_cang@...cinc.com>
To:     Manivannan Sadhasivam <mani@...nel.org>
CC:     <bvanassche@....org>, <adrian.hunter@...el.com>,
        <cmd4@...lcomm.com>, <beanhuo@...ron.com>, <avri.altman@....com>,
        <junwoo80.lee@...sung.com>, <martin.petersen@...cle.com>,
        <linux-scsi@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v6 04/10] scsi: ufs: ufs-qcom: Allow the first init start
 with the maximum supported gear



On 11/30/2023 2:42 PM, Manivannan Sadhasivam wrote:
> On Wed, Nov 29, 2023 at 12:28:29AM -0800, Can Guo wrote:
>> 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.
>>
>> The original check added there is intend to make sure the phy_gear won't be
>> updated when gear is scaled down (during clock scaling). Update the check
>> so that one can start the first init with the maximum support gear without
>> breaking the original fix by checking the ufshcd_state, that is, allow
>> update to phy_gear only if power mode change is invoked from
>> ufshcd_probe_hba().
>>
>> This change is a preparation patch for the next patches in the same series.
> 
> If you happen to respin the series, please remove this line. When the patches
> get merged, there will be no concept of patches/series as all will be git
> commits.
> 
> You can have this information in the comment section (below --- line) though.
> 

Sure, will remove it in next version.

Thanks,
Can Guo.

>>
>> Signed-off-by: Can Guo <quic_cang@...cinc.com>
> 
> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> 
> - Mani
> 
>> ---
>>   drivers/ufs/host/ufs-qcom.c | 9 +++++----
>>   1 file changed, 5 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c
>> index 9a90019..81056b9 100644
>> --- a/drivers/ufs/host/ufs-qcom.c
>> +++ b/drivers/ufs/host/ufs-qcom.c
>> @@ -916,11 +916,12 @@ static int ufs_qcom_pwr_change_notify(struct ufs_hba *hba,
>>   		}
>>   
>>   		/*
>> -		 * Update phy_gear only when the gears are scaled to a higher value. This is
>> -		 * because, the PHY gear settings are backwards compatible and we only need to
>> -		 * change the PHY gear settings while scaling to higher gears.
>> +		 * During UFS driver probe, always update the PHY gear to match the negotiated
>> +		 * gear, so that, if quirk UFSHCD_QUIRK_REINIT_AFTER_MAX_GEAR_SWITCH is enabled,
>> +		 * the second init can program the optimal PHY settings. This allows one to start
>> +		 * the first init with either the minimum or the maximum support gear.
>>   		 */
>> -		if (dev_req_params->gear_tx > host->phy_gear)
>> +		if (hba->ufshcd_state == UFSHCD_STATE_RESET)
>>   			host->phy_gear = dev_req_params->gear_tx;
>>   
>>   		/* enable the device ref clock before changing to HS mode */
>> -- 
>> 2.7.4
>>
>>
>