linux-kernel - Re: [PATCH 1/3] tty: serial: meson: modify request_irq and free

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Date:   Wed, 22 Dec 2021 16:44:22 +0800
From:   Yu Tu <yu.tu@...ogic.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:     <linux-serial@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-amlogic@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, Jiri Slaby <jirislaby@...nel.org>,
        Neil Armstrong <narmstrong@...libre.com>,
        Kevin Hilman <khilman@...libre.com>,
        Jerome Brunet <jbrunet@...libre.com>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Subject: Re: [PATCH 1/3] tty: serial: meson: modify request_irq and free_irq



On 2021/12/21 15:30, Greg Kroah-Hartman wrote:
> [ EXTERNAL EMAIL ]
> 
> On Tue, Dec 21, 2021 at 03:16:32PM +0800, Yu Tu wrote:
>> Change request_irq to devm_request_irq and free_irq to devm_free_irq.
>> It's better to change the code this way.
> 
> Why?  What did this fix up?  You still are manually requesting and
> freeing the irq.  What bug did you fix?
> 
I think this is exactly what you said. It's not necessary.
>>
>> The IRQF_SHARED interrupt flag was added because an interrupt error was
>> detected when the serial port was opened twice in a row on the project.
> 
> That is a different change.  Make that a different patch.
> 
The main purpose of this change is that I found some users in the actual 
project with the following usages:
(1)open(/dev/ttyAML0);
(2)open(/dev/ttyAML0);
The open function calls the meson_uart_startup function. If this is the 
case, an interrupt error is reported.So So the IRQF_SHARED flag was added.

I'm going to do this for now, remove free_irq and request_irq 
function,then add devm_request_irq in meson_uart_probe function.
This solves the above problem without adding IRQF_SHARED.
> thanks,
> 
> greg k-h
>