linux-kernel - Re: [PATCH v4 14/21] thermal/drivers/mediatek/lvts_thermal: convert to use devm_request*_irq

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Date:   Tue, 11 Jul 2023 10:04:54 +0200
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Yangtao Li <frank.li@...o.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Amit Kucheria <amitk@...nel.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Matthias Brugger <matthias.bgg@...il.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH v4 14/21] thermal/drivers/mediatek/lvts_thermal: convert
 to use devm_request*_irq_probe()

Il 10/07/23 11:59, Yangtao Li ha scritto:
> There are more than 700 calls to devm_request_threaded_irq method and
> more than 1000 calls to devm_request_irq method. Most drivers only
> request one interrupt resource, and these error messages are basically
> the same. If error messages are printed everywhere, more than 2000 lines
> of code can be saved by removing the msg in the driver.
> 
> And tglx point out that:
> 
>    If we actually look at the call sites of
>    devm_request_threaded_irq() then the vast majority of them print more or
>    less lousy error messages. A quick grep/sed/awk/sort/uniq revealed
> 
>       519 messages total (there are probably more)
> 
>       352 unique messages
> 
>       323 unique messages after lower casing
> 
>           Those 323 are mostly just variants of the same patterns with
>           slight modifications in formatting and information provided.
> 
>       186 of these messages do not deliver any useful information,
>           e.g. "no irq", "
> 
>       The most useful one of all is: "could request wakeup irq: %d"
> 
>    So there is certainly an argument to be made that this particular
>    function should print a well formatted and informative error message.
> 
>    It's not a general allocator like kmalloc(). It's specialized and in the
>    vast majority of cases failing to request the interrupt causes the
>    device probe to fail. So having proper and consistent information why
>    the device cannot be used _is_ useful.
> 
> So convert to use devm_request*_irq_probe() API, which ensure that all
> error handling branches print error information.
> 
> In this way, when this function fails, the upper-layer functions can
> directly return an error code without missing debugging information.
> Otherwise, the error message will be printed redundantly or missing.
> 
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Krzysztof Kozlowski <krzk@...nel.org>
> Cc: "Uwe Kleine-König" <u.kleine-koenig@...gutronix.de>
> Cc: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> Cc: AngeloGioacchino Del Regno  <angelogioacchino.delregno@...labora.com>
> Signed-off-by: Yangtao Li <frank.li@...o.com>

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>