linux-kernel - Re: [PATCH 05/18] tty: serial: samsung

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Message-ID: <e2bd8f99-58db-4cae-30b3-6fa608bc76dd@marcan.st>
Date:   Sun, 7 Feb 2021 18:26:43 +0900
From:   Hector Martin 'marcan' <marcan@...can.st>
To:     Marc Zyngier <maz@...nel.org>
Cc:     soc@...nel.org, linux-arm-kernel@...ts.infradead.org,
        robh+dt@...nel.org, Arnd Bergmann <arnd@...nel.org>,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        Olof Johansson <olof@...om.net>,
        Krzysztof Kozlowski <krzk@...nel.org>
Subject: Re: [PATCH 05/18] tty: serial: samsung_tty: add support for Apple
 UARTs

On 07/02/2021 18.12, Hector Martin 'marcan' wrote:
> On 06/02/2021 22.15, Marc Zyngier wrote:
>> The default should be IRQ_NONE, otherwise the kernel cannot detect a
>> screaming spurious interrupt.
> 
> Good point, and this needs fixing in s3c64xx_serial_handle_irq too then
> (which is what I based mine off of).
> 
>>> +	ret = request_irq(port->irq, apple_serial_handle_irq, IRQF_SHARED,
>>> +			  s3c24xx_serial_portname(port), ourport);
>>
>> Why IRQF_SHARED? Do you expect any other device sharing the same line
>> with this UART?
> 
> This also came from s3c64xx_serial_startup and... now I wonder why that
> one needs it. Maybe on some SoCs it does get shared? Certainly not for
> discrete rx/tx irq chips (and indeed those don't set the flag)...
> 
> CCing Thomas, who added the S3C64xx support (and should probably review
> this patch); is there a reason for IRQF_SHARED there? NB: v1 breaks the
> build on arm or with CONFIG_PM_SLEEP, those will be fixed for v2.

Seems Thomas does not work for Linaro any more :)

CCing Krzysztof instead, who is the Samsung arch maintainer.

> 
> Either way, certainly not for Apple SoCs; I'll get rid of IRQF_SHARED
> for v2.

-- 
Hector Martin "marcan" (marcan@...can.st)
Public Key: https://mrcn.st/pub