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Subject: Re: [PATCH v3 1/2] scsi: ufs: Refactor ufshcd_setup_clocks() to
 remove skip_ref_clk
To:     Can Guo <cang@codeaurora.org>
Cc:     nguyenb@codeaurora.org, hongwus@codeaurora.org,
        ziqichen@codeaurora.org, rnayak@codeaurora.org,
        linux-scsi@vger.kernel.org, kernel-team@android.com,
        saravanak@google.com, salyzyn@google.com,
        Alim Akhtar <alim.akhtar@samsung.com>,
        Avri Altman <avri.altman@wdc.com>,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Bean Huo <beanhuo@micron.com>,
        Stanley Chu <stanley.chu@mediatek.com>,
        Tomas Winkler <tomas.winkler@intel.com>,
        Bart Van Assche <bvanassche@acm.org>,
        Satya Tangirala <satyat@google.com>,
        open list <linux-kernel@vger.kernel.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-arm-kernel@lists.infradead.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@lists.infradead.org>
References: <1606356063-38380-1-git-send-email-cang@codeaurora.org>
 <1606356063-38380-2-git-send-email-cang@codeaurora.org>
 <f99ee6cd-6e09-4160-f9e8-2d8b04cbfa1e@codeaurora.org>
 <81ac4e5b5974cd7a21f18bf4e74213e9@codeaurora.org>
From:   "Asutosh Das (asd)" <asutoshd@codeaurora.org>
Message-ID: <2e27f15a-988a-fb08-9c51-913a542b7399@codeaurora.org>
Date:   Tue, 1 Dec 2020 08:47:09 -0800
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On 11/30/2020 7:11 PM, Can Guo wrote:
> On 2020-12-01 07:01, Asutosh Das (asd) wrote:
>> On 11/25/2020 6:01 PM, Can Guo wrote:
>>> Remove the param skip_ref_clk from __ufshcd_setup_clocks(), but keep 
>>> a flag
>>> in struct ufs_clk_info to tell whether a clock can be disabled or not 
>>> while
>>> the link is active.
>>>
>>> Reviewed-by: Hongwu Su<hongwus@codeaurora.org>
>>> Reviewed-by: Bean Huo <beanhuo@micron.com>
>>> Reviewed-by: Stanley Chu <stanley.chu@mediatek.com>
>>> Signed-off-by: Can Guo <cang@codeaurora.org>
>>> ---
>>>   drivers/scsi/ufs/ufshcd-pltfrm.c |  2 ++
>>>   drivers/scsi/ufs/ufshcd.c        | 29 +++++++++--------------------
>>>   drivers/scsi/ufs/ufshcd.h        |  3 +++
>>>   3 files changed, 14 insertions(+), 20 deletions(-)
>>>
>>> diff --git a/drivers/scsi/ufs/ufshcd-pltfrm.c 
>>> b/drivers/scsi/ufs/ufshcd-pltfrm.c
>>> index 3db0af6..873ef14 100644
>>> --- a/drivers/scsi/ufs/ufshcd-pltfrm.c
>>> +++ b/drivers/scsi/ufs/ufshcd-pltfrm.c
>>> @@ -92,6 +92,8 @@ static int ufshcd_parse_clock_info(struct ufs_hba 
>>> *hba)
>>>           clki->min_freq = clkfreq[i];
>>>           clki->max_freq = clkfreq[i+1];
>>>           clki->name = kstrdup(name, GFP_KERNEL);
>>> +        if (!strcmp(name, "ref_clk"))
>>> +            clki->keep_link_active = true;
>>>           dev_dbg(dev, "%s: min %u max %u name %s\n", "freq-table-hz",
>>>                   clki->min_freq, clki->max_freq, clki->name);
>>>           list_add_tail(&clki->list, &hba->clk_list_head);
>>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>>> index a7857f6..44254c9 100644
>>> --- a/drivers/scsi/ufs/ufshcd.c
>>> +++ b/drivers/scsi/ufs/ufshcd.c
>>> @@ -221,8 +221,6 @@ static int ufshcd_eh_host_reset_handler(struct 
>>> scsi_cmnd *cmd);
>>>   static int ufshcd_clear_tm_cmd(struct ufs_hba *hba, int tag);
>>>   static void ufshcd_hba_exit(struct ufs_hba *hba);
>>>   static int ufshcd_probe_hba(struct ufs_hba *hba, bool async);
>>> -static int __ufshcd_setup_clocks(struct ufs_hba *hba, bool on,
>>> -                 bool skip_ref_clk);
>>>   static int ufshcd_setup_clocks(struct ufs_hba *hba, bool on);
>>>   static int ufshcd_uic_hibern8_enter(struct ufs_hba *hba);
>>>   static inline void ufshcd_add_delay_before_dme_cmd(struct ufs_hba 
>>> *hba);
>>> @@ -1707,11 +1705,7 @@ static void ufshcd_gate_work(struct 
>>> work_struct *work)
>>>         ufshcd_disable_irq(hba);
>>>   -    if (!ufshcd_is_link_active(hba))
>>> -        ufshcd_setup_clocks(hba, false);
>>> -    else
>>> -        /* If link is active, device ref_clk can't be switched off */
>>> -        __ufshcd_setup_clocks(hba, false, true);
>>> +    ufshcd_setup_clocks(hba, false);
>>>         /*
>>>        * In case you are here to cancel this work the gating state
>>> @@ -7990,8 +7984,7 @@ static int ufshcd_init_hba_vreg(struct ufs_hba 
>>> *hba)
>>>       return 0;
>>>   }
>>>   -static int __ufshcd_setup_clocks(struct ufs_hba *hba, bool on,
>>> -                    bool skip_ref_clk)
>>> +static int ufshcd_setup_clocks(struct ufs_hba *hba, bool on)
>>>   {
>>>       int ret = 0;
>>>       struct ufs_clk_info *clki;
>>> @@ -8009,7 +8002,12 @@ static int __ufshcd_setup_clocks(struct 
>>> ufs_hba *hba, bool on,
>>>         list_for_each_entry(clki, head, list) {
>>>           if (!IS_ERR_OR_NULL(clki->clk)) {
>>> -            if (skip_ref_clk && !strcmp(clki->name, "ref_clk"))
>>> +            /*
>>> +             * Don't disable clocks which are needed
>>> +             * to keep the link active.
>>> +             */
>>> +            if (ufshcd_is_link_active(hba) &&
>>> +                clki->keep_link_active)
>>>                   continue;
>>>                 clk_state_changed = on ^ clki->enabled;
>>> @@ -8054,11 +8052,6 @@ static int __ufshcd_setup_clocks(struct 
>>> ufs_hba *hba, bool on,
>>>       return ret;
>>>   }
>>>   -static int ufshcd_setup_clocks(struct ufs_hba *hba, bool on)
>>> -{
>>> -    return  __ufshcd_setup_clocks(hba, on, false);
>>> -}
>>> -
>>>   static int ufshcd_init_clocks(struct ufs_hba *hba)
>>>   {
>>>       int ret = 0;
>>> @@ -8577,11 +8570,7 @@ static int ufshcd_suspend(struct ufs_hba *hba, 
>>> enum ufs_pm_op pm_op)
>>>        */
>>>       ufshcd_disable_irq(hba);
>>>   -    if (!ufshcd_is_link_active(hba))
>>> -        ufshcd_setup_clocks(hba, false);
>>> -    else
>>> -        /* If link is active, device ref_clk can't be switched off */
>>> -        __ufshcd_setup_clocks(hba, false, true);
>>> +    ufshcd_setup_clocks(hba, false);
>>>         if (ufshcd_is_clkgating_allowed(hba)) {
>>>           hba->clk_gating.state = CLKS_OFF;
>>> diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
>>> index 66e5338..6f0f2d4 100644
>>> --- a/drivers/scsi/ufs/ufshcd.h
>>> +++ b/drivers/scsi/ufs/ufshcd.h
>>> @@ -229,6 +229,8 @@ struct ufs_dev_cmd {
>>>    * @max_freq: maximum frequency supported by the clock
>>>    * @min_freq: min frequency that can be used for clock scaling
>>>    * @curr_freq: indicates the current frequency that it is set to
>>> + * @keep_link_active: indicates that the clk should not be disabled if
>>> +              link is active
>>>    * @enabled: variable to check against multiple enable/disable
>>>    */
>>>   struct ufs_clk_info {
>>> @@ -238,6 +240,7 @@ struct ufs_clk_info {
>>>       u32 max_freq;
>>>       u32 min_freq;
>>>       u32 curr_freq;
>>> +    bool keep_link_active;
>>
>> Nitpick - How about 'always-on' instead of 'keep_link_active'?
> 
> Hi Asutosh,
> 
> But it is not always-on, during suspend, it is on when rpm/spm-lvl is 1
> and 2, off when rpm/spm-lvl is 3, 4 and 5, depending on the link state.
> 

Understood & agree.


> Thanks,
> 
> Can Guo.
> 
>>>       bool enabled;
>>>   };
>>>


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