linux-kernel - Re: [PATCH v2] leds: USB: Add support for MSI GT683R led panels

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Message-ID: <CAEEjW04UAsi7yOdmF3FZ3sLE7m7B-VAH0prDPYjaMXarAfNwcw@mail.gmail.com>
Date:	Sat, 7 Jun 2014 13:12:39 +0300
From:	Janne Kanniainen <janne.kanniainen@...il.com>
To:	Johan Hovold <johan@...nel.org>
Cc:	Bryan Wu <cooloney@...il.com>, rpurdie@...ys.net,
	linux-kernel@...r.kernel.org, linux-leds@...r.kernel.org,
	linux-usb@...r.kernel.org, Jiri Kosina <jkosina@...e.cz>,
	linux-input@...r.kernel.org
Subject: Re: [PATCH v2] leds: USB: Add support for MSI GT683R led panels

> First of all, please reply to the original thread and make sure to not
> drop people or lists from CC.

Sorry this is my first patch and i didn't know that. Now I know.

> For arrays you can use the ARRAY_SIZE() macro if that was the reason for
> this change. I should have mentioned that when I pointed out that you
> cannot use strlen().

That wasn't the reason. I just thought it might be better to use u64
than char[8]. I know why I can't use strlen and that was only careless
error. And there was lot of them :( I will be more careful next time.

> Where did you get these (HID report) values from by the way?

I got them by reverse engineering.

>> +
>> +static void gt683r_brightness_set(struct led_classdev *led_cdev,
>> +                               enum led_brightness brightness)
>> +{
>> +     struct gt683r_led *led =
>> +                     container_of(led_cdev, struct gt683r_led, led_dev);
>> +
>> +     mutex_lock(&led->lock);
>
> You cannot grab a mutex here since this function can be called from
> interrupt context (if I remember correctly). Either way, you shouldn't
> be holding the lock until the work task has finished...

I thought use asked me to put some lock there:

>> +
>> +static void gt683r_brightness_set(struct led_classdev *led_cdev,
>> +                               enum led_brightness brightness)
>> +{
>> +     struct gt683r_led *led =
>> +                     container_of(led_cdev, struct gt683r_led, led_dev);
>> +
>> +     led->brightness = brightness;
>
> Missing locking?

Janne
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