linux-kernel - Re: [PATCH 08/10] ufs-qcom: phy/hcd: Refactoring phy clock handling

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Message-ID: <CAFp+6iGN3_1+9Rj+ewMucMY2gVWpSuszM8_dB2Xu4a_iT+ZAHw@mail.gmail.com>
Date:   Wed, 19 Oct 2016 23:15:14 +0530
From:   Vivek Gautam <vivek.gautam@...eaurora.org>
To:     Subhash Jadavani <subhashj@...eaurora.org>
Cc:     kishon <kishon@...com>, jejb@...ux.vnet.ibm.com,
        vinholikatti@...il.com, martin.petersen@...cle.com,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        linux-scsi@...r.kernel.org, linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH 08/10] ufs-qcom: phy/hcd: Refactoring phy clock handling

Hi,


On Wed, Oct 19, 2016 at 1:43 AM, Subhash Jadavani
<subhashj@...eaurora.org> wrote:
> On 2016-10-18 07:28, Vivek Gautam wrote:
>>
>> Add phy clock enable code to phy_power_on/off callbacks, and
>> remove explicit calls to enable these phy clocks from the
>> ufs-qcom hcd driver.
>>
>> Signed-off-by: Vivek Gautam <vivek.gautam@...eaurora.org>
>> ---
>>
>> Changes since v1:
>>  - staticized ufs_qcom_phy_enable(/disable)_ref_clk(),
>>  - staticized ufs_qcom_phy_enable(/disable)_iface_clk()
>>  - removed function declaration and export symbol for these APIs.

[snip]

>> --- a/drivers/scsi/ufs/ufs-qcom.c
>> +++ b/drivers/scsi/ufs/ufs-qcom.c
>> @@ -1112,17 +1112,6 @@ static int ufs_qcom_setup_clocks(struct ufs_hba
>> *hba, bool on)
>>                 return 0;
>>
>>         if (on) {
>> -               err = ufs_qcom_phy_enable_iface_clk(host->generic_phy);
>> -               if (err)
>> -                       goto out;
>> -
>> -               err = ufs_qcom_phy_enable_ref_clk(host->generic_phy);
>> -               if (err) {
>> -                       dev_err(hba->dev, "%s enable phy ref clock failed,
>> err=%d\n",
>> -                               __func__, err);
>> -                       ufs_qcom_phy_disable_iface_clk(host->generic_phy);
>> -                       goto out;
>> -               }
>
>
> Now that you are moving these ref clk enable/disable to phy_power_on/off and
> these phy_power_on/off are called only in runtime suspend/resume (3 seconds
> after last UFS access).
> Goal is to disable the phy reference clock during aggressive gating (10ms
> from last UFS access) so shouldn't we call the phy_power_on/off from these
> setup_clocks() function as well?
>

So setup_clocks() is called for aggressive clock gating as well ?
If that's the case then yes, we may need to call. But we should try to
understand here. The phy_power_off turns off all the clocks - reflclk,
and other interface clocks. Do we want all of them to be turned off ?

phy_power_off will also turn off the PHY. Do we want all this for aggressive
clock gating ?


[snip]


Regards
Vivek

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