linux-kernel - Re: [PATCH] devfreq: tegra: fix error code in tegra_devfreq

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Message-ID: <20170703065905.Horde.JGioNMGT4RgQsy5ykZpOZQ1@gator4166.hostgator.com>
Date:   Mon, 03 Jul 2017 06:59:05 -0500
From:   "Gustavo A. R. Silva" <garsilva@...eddedor.com>
To:     Jon Hunter <jonathanh@...dia.com>
Cc:     MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Thierry Reding <thierry.reding@...il.com>,
        linux-pm@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] devfreq: tegra: fix error code in tegra_devfreq_probe()

Hi Jon,

Quoting Jon Hunter <jonathanh@...dia.com>:

> On 30/06/17 08:22, Gustavo A. R. Silva wrote:
>> Print and propagate the return value of platform_get_irq on failure.
>>
>> Signed-off-by: Gustavo A. R. Silva <garsilva@...eddedor.com>
>> ---
>>  drivers/devfreq/tegra-devfreq.c | 6 +++---
>>  1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/devfreq/tegra-devfreq.c  
>> b/drivers/devfreq/tegra-devfreq.c
>> index 214fff9..ae71215 100644
>> --- a/drivers/devfreq/tegra-devfreq.c
>> +++ b/drivers/devfreq/tegra-devfreq.c
>> @@ -688,9 +688,9 @@ static int tegra_devfreq_probe(struct  
>> platform_device *pdev)
>>  	}
>>
>>  	irq = platform_get_irq(pdev, 0);
>> -	if (irq <= 0) {
>> -		dev_err(&pdev->dev, "Failed to get IRQ\n");
>> -		return -ENODEV;
>> +	if (irq < 0) {
>
> The changelog does not describe the above change and if/why this is ok.
> However, the original test looks fine to me and so I don't see a need to
> change this.
>

You are right about the changelog. I think this one is much better:

platform_get_irq() returns an error code, but the tegra-devfreq
driver ignores it and always returns -ENODEV. This is not correct,
and prevents -EPROBE_DEFER from being propagated properly.

Notice that platform_get_irq() no longer returns 0 on error:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e330b9a6bb35dc7097a4f02cb1ae7b6f96df92af

Print error message and propagate the return value of
platform_get_irq on failure.


What do you think?

Thank you!
--
Gustavo A. R. Silva