linux-kernel - Re: [PATCH 1/2] usb: dwc3: support continuous runtime PM with dual role

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <ef22f8de-9bfd-c1d5-111c-696f1336dbda@puri.sm>
Date:   Wed, 18 Mar 2020 12:16:56 +0100
From:   Martin Kepplinger <martin.kepplinger@...i.sm>
To:     Roger Quadros <rogerq@...com>, balbi@...nel.org, robh@...nel.org
Cc:     gregkh@...uxfoundation.org, linux-usb@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] usb: dwc3: support continuous runtime PM with dual
 role



On 18.03.20 12:13, Roger Quadros wrote:
> Martin,
> 
> On 18/03/2020 10:35, Martin Kepplinger wrote:
>> The DRD module calls dwc3_set_mode() on role switches, i.e. when a
>> device is
>> being pugged in. In order to support continuous runtime power
>> management when
>> plugging in / unplugging a cable, we need to call pm_runtime_get() in
>> this path.
>>
>> Signed-off-by: Martin Kepplinger <martin.kepplinger@...i.sm>
>> ---
>>   drivers/usb/dwc3/core.c | 5 +++++
>>   1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
>> index edc17155cb2b..7743c4de82e9 100644
>> --- a/drivers/usb/dwc3/core.c
>> +++ b/drivers/usb/dwc3/core.c
>> @@ -196,11 +196,16 @@ void dwc3_set_mode(struct dwc3 *dwc, u32 mode)
>>   {
>>       unsigned long flags;
>>   +    pm_runtime_get(dwc->dev);
>> +
>>       spin_lock_irqsave(&dwc->lock, flags);
>>       dwc->desired_dr_role = mode;
>>       spin_unlock_irqrestore(&dwc->lock, flags);
>>         queue_work(system_freezable_wq, &dwc->drd_work);
> 
> We are not touching any IP registers and just scheduling
> the drd_work in this function so it doesn't make sense to do
> pm_runtime_get here.
> 
> How about dong pm_runtime_get/put in __dwc3_set_mode()?

That would be more accurate indeed. I'll move it over there. thanks for
having a look!

                           martin


> 
>> +
>> +    pm_runtime_mark_last_busy(dwc->dev);
>> +    pm_runtime_put_autosuspend(dwc->dev);
>>   }
>>     u32 dwc3_core_fifo_space(struct dwc3_ep *dep, u8 type)
>>
>