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Date:   Tue, 01 Dec 2020 11:11:57 +0800
From:   Can Guo <cang@codeaurora.org>
To:     "Asutosh Das (asd)" <asutoshd@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>
Subject: Re: [PATCH v3 1/2] scsi: ufs: Refactor ufshcd_setup_clocks() to
 remove skip_ref_clk
In-Reply-To: <f99ee6cd-6e09-4160-f9e8-2d8b04cbfa1e@codeaurora.org>
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 <f99ee6cd-6e09-4160-f9e8-2d8b04cbfa1e@codeaurora.org>
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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.

Thanks,

Can Guo.

>>   	bool enabled;
>>   };
>>