linux-kernel - Re: [PATCH v5 06/10] scsi: ufs: ufs-qcom: Limit HS-G5 Rate-A to hosts with HW version 5

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Date:   Tue, 28 Nov 2023 15:48:02 +0800
From:   Can Guo <quic_cang@...cinc.com>
To:     Manivannan Sadhasivam <mani@...nel.org>
CC:     <bvanassche@....org>, <adrian.hunter@...el.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 v5 06/10] scsi: ufs: ufs-qcom: Limit HS-G5 Rate-A to hosts
 with HW version 5

Hi Mani,

On 11/28/2023 1:55 PM, Manivannan Sadhasivam wrote:
> On Thu, Nov 23, 2023 at 12:46:26AM -0800, Can Guo wrote:
>> Qcom UFS hosts, with HW ver 5, can only support up to HS-G5 Rate-A due to
>> HW limitations. If the HS-G5 PHY gear is used, update host_params->hs_rate
>> to Rate-A, so that the subsequent power mode changes shall stick to Rate-A.
>>
>> Signed-off-by: Can Guo <quic_cang@...cinc.com>
> 
> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> 
> One question below...
> 
>> ---
>>   drivers/ufs/host/ufs-qcom.c | 18 +++++++++++++++++-
>>   1 file changed, 17 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c
>> index 9613ad9..6756f8d 100644
>> --- a/drivers/ufs/host/ufs-qcom.c
>> +++ b/drivers/ufs/host/ufs-qcom.c
>> @@ -442,9 +442,25 @@ static u32 ufs_qcom_get_hs_gear(struct ufs_hba *hba)
>>   static int ufs_qcom_power_up_sequence(struct ufs_hba *hba)
>>   {
>>   	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
>> +	struct ufs_host_params *host_params = &host->host_params;
>>   	struct phy *phy = host->generic_phy;
>> +	enum phy_mode mode;
>>   	int ret;
>>   
>> +	/*
>> +	 * HW ver 5 can only support up to HS-G5 Rate-A due to HW limitations.
>> +	 * If the HS-G5 PHY gear is used, update host_params->hs_rate to Rate-A,
>> +	 * so that the subsequent power mode change shall stick to Rate-A.
>> +	 */
>> +	if (host->hw_ver.major == 0x5) {
>> +		if (host->phy_gear == UFS_HS_G5)
>> +			host_params->hs_rate = PA_HS_MODE_A;
>> +		else
>> +			host_params->hs_rate = PA_HS_MODE_B;
> 
> Is this 'else' part really needed? Since there wouldn't be any 2nd init, I think
> we can skip that.

We need it because, even there is only one init, if a UFS3.1 device is 
attached, phy_gear is given as UFS_HS_G4 in ufs_qcom_set_phy_gear(), 
hence we need to put the UFS at HS-G4 Rate B, not Rate A.

Thanks,
Can Guo.

> 
> - Mani
> 
>> +	}
>> +
>> +	mode = host_params->hs_rate == PA_HS_MODE_B ? PHY_MODE_UFS_HS_B : PHY_MODE_UFS_HS_A;
>> +
>>   	/* Reset UFS Host Controller and PHY */
>>   	ret = ufs_qcom_host_reset(hba);
>>   	if (ret)
>> @@ -459,7 +475,7 @@ static int ufs_qcom_power_up_sequence(struct ufs_hba *hba)
>>   		return ret;
>>   	}
>>   
>> -	phy_set_mode_ext(phy, PHY_MODE_UFS_HS_B, host->phy_gear);
>> +	phy_set_mode_ext(phy, mode, host->phy_gear);
>>   
>>   	/* power on phy - start serdes and phy's power and clocks */
>>   	ret = phy_power_on(phy);
>> -- 
>> 2.7.4
>>
>