linux-kernel - Re: [PATCH] driver core: platform: return -ENXIO for missing GpioInt

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Date:   Mon, 29 Jul 2019 13:54:52 -0700
From:   Nathan Chancellor <natechancellor@...il.com>
To:     Brian Norris <briannorris@...omium.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        linux-kernel@...r.kernel.org, andriy.shevchenko@...ux.intel.com,
        Salvatore Bellizzi <salvatore.bellizzi@...ux.seppia.net>,
        andy.shevchenko@...il.com,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        egranata@...omium.org, egranata@...gle.com,
        Enric Balletbo i Serra <enric.balletbo@...labora.com>,
        Gwendal Grignou <gwendal@...omium.org>,
        linux-acpi@...r.kernel.org, Benson Leung <bleung@...omium.org>,
        stable@...r.kernel.org
Subject: Re: [PATCH] driver core: platform: return -ENXIO for missing GpioInt

On Mon, Jul 29, 2019 at 01:49:54PM -0700, Brian Norris wrote:
> Commit daaef255dc96 ("driver: platform: Support parsing GpioInt 0 in
> platform_get_irq()") broke the Embedded Controller driver on most LPC
> Chromebooks (i.e., most x86 Chromebooks), because cros_ec_lpc expects
> platform_get_irq() to return -ENXIO for non-existent IRQs.
> Unfortunately, acpi_dev_gpio_irq_get() doesn't follow this convention
> and returns -ENOENT instead. So we get this error from cros_ec_lpc:
> 
>    couldn't retrieve IRQ number (-2)
> 
> I see a variety of drivers that treat -ENXIO specially, so rather than
> fix all of them, let's fix up the API to restore its previous behavior.
> 
> I reported this on v2 of this patch:
> 
> https://lore.kernel.org/lkml/20190220180538.GA42642@google.com/
> 
> but apparently the patch had already been merged before v3 got sent out:
> 
> https://lore.kernel.org/lkml/20190221193429.161300-1-egranata@chromium.org/
> 
> and the result is that the bug landed and remains unfixed.
> 
> I differ from the v3 patch by:
>  * allowing for ret==0, even though acpi_dev_gpio_irq_get() specifically
>    documents (and enforces) that 0 is not a valid return value (noted on
>    the v3 review)
>  * adding a small comment
> 
> Reported-by: Brian Norris <briannorris@...omium.org>
> Reported-by: Salvatore Bellizzi <salvatore.bellizzi@...ux.seppia.net>
> Cc: Enrico Granata <egranata@...omium.org>
> Cc: <stable@...r.kernel.org>
> Fixes: daaef255dc96 ("driver: platform: Support parsing GpioInt 0 in platform_get_irq()")
> Signed-off-by: Brian Norris <briannorris@...omium.org>
> ---
> Side note: it might have helped alleviate some of this pain if there
> were email notifications to the mailing list when a patch gets applied.
> I didn't realize (and I'm not sure if Enrico did) that v2 was already
> merged by the time I noted its mistakes. If I had known, I would have
> suggested a follow-up patch, not a v3.

I've found this to be fairly reliable for getting notified when
something gets applied if it is a tree that shows up in -next.

https://www.kernel.org/get-notifications-for-your-patches.html

Cheers,
Nathan