linux-kernel - Re: [PATCH v1 1/1] backlight: mp3309c: fix leds flickering in pwm mode

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Message-ID: <20240418084157.GA162404@aspen.lan>
Date: Thu, 18 Apr 2024 09:41:57 +0100
From: Daniel Thompson <daniel.thompson@...aro.org>
To: Flavio Suligoi <f.suligoi@...m.it>
Cc: Lee Jones <lee@...nel.org>, Jingoo Han <jingoohan1@...il.com>,
	Helge Deller <deller@....de>,
	Dan Carpenter <dan.carpenter@...aro.org>,
	dri-devel@...ts.freedesktop.org, linux-fbdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 1/1] backlight: mp3309c: fix leds flickering in pwm
 mode

On Wed, Apr 17, 2024 at 05:31:05PM +0200, Flavio Suligoi wrote:
> The mp3309 has two configuration registers, named according to their
> address (0x00 and 0x01).
> In the second register (0x01), the bit DIMS (Dimming Mode Select) must
> be always 0 (zero), in both analog (via i2c commands) and pwm dimming
> mode.
>
> In the initial driver version, the DIMS bit was set in pwm mode and
> reset in analog mode.
> But if the DIMS bit is set in pwm dimming mode and other devices are
> connected on the same i2c bus, every i2c commands on the bus generates a
> flickering on the LEDs powered by the mp3309c.
>
> This change concerns the chip initialization and does not impact any
> existing device-tree configuration.
>
> Signed-off-by: Flavio Suligoi <f.suligoi@...m.it>

Reviewed-by: Daniel Thompson <daniel.thompson@...aro.org>


Daniel.