linux-kernel - Re: [PATCH] leds: pca963x: Fix open-drain initialization

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Message-ID: <20191103170327.GA32107@duo.ucw.cz>
Date:   Mon, 4 Nov 2019 10:09:53 +0100
From:   Pavel Machek <pavel@....cz>
To:     Zahari Petkov <zahari@...ena.io>
Cc:     Jacek Anaszewski <jacek.anaszewski@...il.com>,
        Dan Murphy <dmurphy@...com>, linux-leds@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] leds: pca963x: Fix open-drain initialization

On Mon 2019-10-14 15:36:04, Zahari Petkov wrote:
> OUTDRV setting (bit 2) of Mode register 2 has a default value of 1.
> During initialization when open-drain is used, instead of setting
> OUTDRV to 0, the driver keeps it as 1. OUTDRV setting is now correctly
> initialized to 0 when open-drain is used.
> 
> Additionally the BIT macro is used for improved readibility.

You change more than you describe in the changelog.

> +++ b/drivers/leds/leds-pca963x.c
> @@ -438,12 +438,12 @@ static int pca963x_probe(struct i2c_client *client,
>  						    PCA963X_MODE2);
>  		/* Configure output: open-drain or totem pole (push-pull) */
>  		if (pdata->outdrv == PCA963X_OPEN_DRAIN)
> -			mode2 |= 0x01;
> +			mode2 &= ~BIT(2);

| 0 -> & ~0x04;

>  		else
> -			mode2 |= 0x05;
> +			mode2 |= BIT(2);

| 5 -> | 0x04;

Are you sure?

Additionaly, we already have defines for bits in mode2 register:

#define PCA963X_MODE2_DMBLNK    0x20    /* Enable blinking */

So if you care about readability, perhaps you should add defines for
invert/ open drain there, and then use them?

Please keep using 0xab instead of BIT() for consistency with the rest
of the driver.

Thanks,
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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