linux-kernel - Re: [PATCH V2 2/2] scsi: ufs: introduce quirk to extend PA

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Message-ID: <cf81fc11-f47b-422c-9c7d-860e6f93d930@quicinc.com>
Date: Tue, 8 Apr 2025 22:58:10 +0530
From: MANISH PANDEY <quic_mapa@...cinc.com>
To: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
CC: "James E.J. Bottomley" <James.Bottomley@...senpartnership.com>,
        "Martin K.
 Petersen" <martin.petersen@...cle.com>,
        Alim Akhtar
	<alim.akhtar@...sung.com>,
        Avri Altman <avri.altman@....com>,
        Bart Van Assche
	<bvanassche@....org>, <linux-scsi@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
        <quic_nitirawa@...cinc.com>, <quic_bhaskarv@...cinc.com>,
        <quic_rampraka@...cinc.com>, <quic_cang@...cinc.com>,
        <quic_nguyenb@...cinc.com>
Subject: Re: [PATCH V2 2/2] scsi: ufs: introduce quirk to extend
 PA_HIBERN8TIME for UFS devices



On 4/8/2025 10:01 PM, Manivannan Sadhasivam wrote:
> On Tue, Apr 08, 2025 at 01:14:50PM +0530, MANISH PANDEY wrote:
>>
>>
>> On 4/8/2025 12:53 PM, Manivannan Sadhasivam wrote:
>>> On Tue, Apr 08, 2025 at 11:07:58AM +0530, MANISH PANDEY wrote:
>>>>
>>>>
>>>> On 4/7/2025 12:05 AM, Manivannan Sadhasivam wrote:
>>>>> On Fri, Apr 04, 2025 at 11:15:39PM +0530, Manish Pandey wrote:
>>>>>> Some UFS devices need additional time in hibern8 mode before exiting,
>>>>>> beyond the negotiated handshaking phase between the host and device.
>>>>>> Introduce a quirk to increase the PA_HIBERN8TIME parameter by 100 µs
>>>>>> to ensure proper hibernation process.
>>>>>>
>>>>>
>>>>> This commit message didn't mention the UFS device for which this quirk is being
>>>>> applied.
>>>>>
>>>> Since it's a quirk and may be applicable to other vendors also in future, so
>>>> i thought to keep it general.
>>>>
>>>
>>> You cannot make commit message generic. It should precisely describe the change.
>>>
>>>> Will update in next patch set if required.
>>>>    >> Signed-off-by: Manish Pandey <quic_mapa@...cinc.com>
>>>>>> ---
>>>>>>     drivers/ufs/core/ufshcd.c | 31 +++++++++++++++++++++++++++++++
>>>>>>     include/ufs/ufs_quirks.h  |  6 ++++++
>>>>>>     2 files changed, 37 insertions(+)
>>>>>>
>>>>>> diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
>>>>>> index 464f13da259a..2b8203fe7b8c 100644
>>>>>> --- a/drivers/ufs/core/ufshcd.c
>>>>>> +++ b/drivers/ufs/core/ufshcd.c
>>>>>> @@ -278,6 +278,7 @@ static const struct ufs_dev_quirk ufs_fixups[] = {
>>>>>>     	  .model = UFS_ANY_MODEL,
>>>>>>     	  .quirk = UFS_DEVICE_QUIRK_DELAY_BEFORE_LPM |
>>>>>>     		   UFS_DEVICE_QUIRK_HOST_PA_TACTIVATE |
>>>>>> +		   UFS_DEVICE_QUIRK_PA_HIBER8TIME |
>>>>>>     		   UFS_DEVICE_QUIRK_RECOVERY_FROM_DL_NAC_ERRORS },
>>>>>>     	{ .wmanufacturerid = UFS_VENDOR_SKHYNIX,
>>>>>>     	  .model = UFS_ANY_MODEL,
>>>>>> @@ -8384,6 +8385,33 @@ static int ufshcd_quirk_tune_host_pa_tactivate(struct ufs_hba *hba)
>>>>>>     	return ret;
>>>>>>     }
>>>>>> +/**
>>>>>> + * ufshcd_quirk_override_pa_h8time - Ensures proper adjustment of PA_HIBERN8TIME.
>>>>>> + * @hba: per-adapter instance
>>>>>> + *
>>>>>> + * Some UFS devices require specific adjustments to the PA_HIBERN8TIME parameter
>>>>>> + * to ensure proper hibernation timing. This function retrieves the current
>>>>>> + * PA_HIBERN8TIME value and increments it by 100us.
>>>>>> + */
>>>>>> +static void ufshcd_quirk_override_pa_h8time(struct ufs_hba *hba)
>>>>>> +{
>>>>>> +	u32 pa_h8time = 0;
>>>>>
>>>>> Why do you need to initialize it?
>>>>>
>>>> Agree.. Not needed, will update.>> +	int ret;
>>>>>> +
>>>>>> +	ret = ufshcd_dme_get(hba, UIC_ARG_MIB(PA_HIBERN8TIME),
>>>>>> +			&pa_h8time);
>>>>>> +	if (ret) {
>>>>>> +		dev_err(hba->dev, "Failed to get PA_HIBERN8TIME: %d\n", ret);
>>>>>> +		return;
>>>>>> +	}
>>>>>> +
>>>>>> +	/* Increment by 1 to increase hibernation time by 100 µs */
>>>>>
>>>>>    From where the value of 100us adjustment is coming from?
>>>>>
>>>>> - Mani
>>>>>
>>>> These values are derived from experiments on Qualcomm SoCs.
>>>> However this is also matching with ufs-exynos.c
>>>>
>>>
>>> Okay. In that case, you should mention that the 100us value is derived from
>>> experiments on Qcom and Samsung SoCs. Otherwise, it gives an assumption that
>>> this value is universal.
>>>
>>> - Mani
>>>
>>   << Otherwise, it gives an assumption that this value is universal. >>
>> So with this, should i add this quirk for Qcom only, or should add in
>> ufshcd.c and make it common for all SoC vendors?
>>
> 
> You can add the quirk for both Qcom and Samsung. My comment was about clarifying
> it in the kernel doc comments.
> 
> - Mani
> 
Just for conclusion, why i moved this quirk from ufs-qcom to ufshcd.c is 
as per Bart's suggestion in patchset 
https://lore.kernel.org/lkml/c0691392-1523-4863-a722-d4f4640e4e28@acm.org/

<< Which of these quirks are required for all host controllers and which 
of these quirks are only required for Qualcomm host controllers?

 > Should we consider moving the QUIRK_PA_HIBER8TIME quirk to the ufshcd
 > driver? Please advise.

That would be appreciated. >>

Just to brief, QUIRK_PA_HIBER8TIME is required for Samsung UFS devices 
and may be applicable to all SoC vendors with Samsung ufs device.

If you suggest to move it to ufs-qcom.c, i don't have any concern.
BTW Samsung UFS driver already has this implemented in their driver,
So i need not have to add this quirk to Samsung driver (ufs-exynos.c).

Regards
Manish