linux-kernel - Re: [PATCH v3 14/16] phy: Add notify

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Date:   Wed, 20 Dec 2017 12:47:56 +0530
From:   Kishon Vijay Abraham I <kishon@...com>
To:     Manu Gautam <mgautam@...eaurora.org>
CC:     <linux-arm-msm@...r.kernel.org>, <linux-usb@...r.kernel.org>,
        "open list:GENERIC PHY FRAMEWORK" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 14/16] phy: Add notify_speed callback

Hi,

On Wednesday 20 December 2017 11:59 AM, Manu Gautam wrote:
> Hi,
> 
> 
> On 12/20/2017 11:19 AM, Kishon Vijay Abraham I wrote:
>> Hi,
>>
>> On Tuesday 12 December 2017 08:54 PM, Manu Gautam wrote:
>>> Hi,
>>>
>>>
>>> On 12/12/2017 5:13 PM, Kishon Vijay Abraham I wrote:
>>>> Hi,
>>>>
>>>> On Tuesday 21 November 2017 02:53 PM, Manu Gautam wrote:
>>>>> QCOM USB PHYs can monitor resume/remote-wakeup event in
>>>>> suspended state. However PHY driver must know current
>>>>> operational speed of PHY in order to set correct polarity of
>>>>> wakeup events for detection. E.g. QUSB2 PHY monitors DP/DM
>>>>> signals depending on speed is LS or FS/HS to detect resume.
>>>>> Similarly QMP USB3 PHY in SS mode should monitor RX
>>>>> terminations attach/detach and LFPS events depending on
>>>>> SSPHY is active or not.
>> Why not use a notification mechanism instead of adding new APIs in phy-core.
>> This will only bloat phy-core with APIs for a particular platform.
> 
> Do you mean notifier_chains ?
> When we have multiple instances of USB PHYs then notifier chains are not
> of much help. For any platform glue or PHY driver it will be very difficult to
> figure out if notification received for speed was for same phy/bus or a
> different one.
> Using PHY callbacks looked more elegant to me. Additionally PHY drivers
> can also use this info decide power management policy e.g. if speed is
> INVALID then it means PHY is not in a session and it can enter deepest
> low power state.
> Additionally if you prefer set_speed name over notify_speed then I am
> ok with that as well so that it sounds more generic.

I'd prefer adding modes in enum phy_mode according to speed and using phy_set_mode.

Thanks
Kishon