Re: [PATCH] tty: serial: qcom_geni: avoid duplicate struct member init

From: "Arnd Bergmann" <arnd@arndb.de>
To: "Doug Anderson" <dianders@chromium.org>,
	"Arnd Bergmann" <arnd@kernel.org>
Cc: "Andy Gross" <agross@kernel.org>,
	"Bjorn Andersson" <andersson@kernel.org>,
	"Konrad Dybcio" <konrad.dybcio@linaro.org>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Jiri Slaby" <jirislaby@kernel.org>,
	"Vijaya Krishna Nivarthi" <quic_vnivarth@quicinc.com>,
	"Sai Prakash Ranjan" <quic_saipraka@quicinc.com>,
	"Aniket Randive" <quic_arandive@quicinc.com>,
	linux-arm-msm@vger.kernel.org, linux-serial@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] tty: serial: qcom_geni: avoid duplicate struct member init
Date: Fri, 16 Dec 2022 11:03:10 +0100	[thread overview]
Message-ID: <02b4b94c-aa0d-4878-906d-ecd947553f16@app.fastmail.com> (raw)
In-Reply-To: <CAD=FV=U6pfSk0nY+s-p4f43Gq6-arfr8hQe8d9NC0nS0ckMYKw@mail.gmail.com>

On Thu, Dec 15, 2022, at 21:46, Doug Anderson wrote:
> On Thu, Dec 15, 2022 at 8:55 AM Arnd Bergmann <arnd@kernel.org> wrote:

>> index b487823f0e61..03dda47184d9 100644
>> --- a/drivers/tty/serial/qcom_geni_serial.c
>> +++ b/drivers/tty/serial/qcom_geni_serial.c
>> @@ -1516,7 +1516,7 @@ static int qcom_geni_serial_remove(struct platform_device *pdev)
>>         return 0;
>>  }
>>
>> -static int __maybe_unused qcom_geni_serial_sys_suspend(struct device *dev)
>> +static int qcom_geni_serial_sys_suspend(struct device *dev)
>
> Officially the removal of "__maybe_unused" could be a totally
> different patch, right? SET_SYSTEM_SLEEP_PM_OPS() already eventually
> used pm_sleep_ptr() even without your change, so the removal of these
> tags is unrelated to the rest of your change, right?

It's a little more complicated: SYSTEM_SLEEP_PM_OPS() uses pm_sleep_ptr()
to avoid the need for a __maybe_unused(). The depreacated
SET_SYSTEM_SLEEP_PM_OPS() is based on SYSTEM_SLEEP_PM_OPS() these days,
but still retains the old semantics of using an empty definition
without CONFIG_PM_SLEEP, so it still leaves the function unused as
far as gcc is concerned.

There could be an intermediate step of open-coding the
SET_SYSTEM_SLEEP_PM_OPS(), but that would result in the rather
silly

 static const struct dev_pm_ops qcom_geni_serial_pm_ops = {
#ifdef CONFIG_PM_SLEEP
       .suspend = qcom_geni_serial_sys_suspend,
       .resume = qcom_geni_serial_sys_resume,
       .freeze = qcom_geni_serial_sys_suspend,
       .poweroff = qcom_geni_serial_sys_suspend,
#endif
       .restore = qcom_geni_serial_sys_hib_resume,
       .thaw = qcom_geni_serial_sys_hib_resume,
}

which makes no sense to me, as I think you either want
all the members or none of them.

>>  static const struct dev_pm_ops qcom_geni_serial_pm_ops = {
>> -       SET_SYSTEM_SLEEP_PM_OPS(qcom_geni_serial_sys_suspend,
>> -                                       qcom_geni_serial_sys_resume)
>> -       .restore = qcom_geni_serial_sys_hib_resume,
>> -       .thaw = qcom_geni_serial_sys_hib_resume,
>> +       .suspend = pm_sleep_ptr(qcom_geni_serial_sys_suspend),
>> +       .resume = pm_sleep_ptr(qcom_geni_serial_sys_resume),
>> +       .freeze = pm_sleep_ptr(qcom_geni_serial_sys_suspend),
>> +       .poweroff = pm_sleep_ptr(qcom_geni_serial_sys_suspend),
>> +       .restore = pm_sleep_ptr(qcom_geni_serial_sys_hib_resume),
>> +       .thaw = pm_sleep_ptr(qcom_geni_serial_sys_hib_resume),
>
> Personally, the order you listed them is less intuitive than the order
> that SET_SYSTEM_SLEEP_PM_OPS() lists functions. IMO it's better to
> consistently alternate matching suspend/resume functions. ;-)

Makes sense. I kept the order that we already had here, but
I could redo this patch if anyone cares.

> Both of those are nits, so I'm also fine with:
>
> Reviewed-by: Douglas Anderson <dianders@chromium.org>

Thanks,

     Arnd