linux-kernel - Re: [PATCH] pwm: samsung: Simplify using devm_pwmchip

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Date:   Wed, 1 Sep 2021 11:42:22 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
To:     zhaoxiao <zhaoxiao@...ontech.com>, thierry.reding@...il.com,
        lee.jones@...aro.org
Cc:     u.kleine-koenig@...gutronix.de,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-pwm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] pwm: samsung: Simplify using devm_pwmchip_add()

On 01/09/2021 11:11, zhaoxiao wrote:
> Thanks for your advices, This patch is modified with reference to the 
> patch that has been submitted，example:
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git/commit/?h=staging-testing&id=66a03c4fd9e95e192c574811a1f4ea8f62992358
> 

The patch there looks correct, but you cannot apply one code pattern to
entirely different code and hope it works.

You reference a patch in a driver not using drvdata and having only
pwmchip_remove() in its remove() callback.

Now you apply it to other drivers and:
1. Remove drvdata even though it is used,
2. Delete additional code from remove() callback.

Especially the point (2) is a proof that you don't understand the
fundamental Linux driver model, so please do not convert code into
devm-like() before learning it.

Best regards,
Krzysztof