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From: Robert Jarzmik <robert.jarzmik@free.fr>
To: Sascha Hauer <s.hauer@pengutronix.de>
Cc: barebox@lists.infradead.org
Subject: Re: [PATCH] drivers/pwm: add PXA pulse width modulator controller
Date: Fri, 03 Feb 2012 16:39:18 +0100	[thread overview]
Message-ID: <87mx903p09.fsf@free.fr> (raw)
In-Reply-To: <20120203095205.GF1990@pengutronix.de> (Sascha Hauer's message of "Fri, 3 Feb 2012 10:52:05 +0100")

Sascha Hauer <s.hauer@pengutronix.de> writes:

> Hi Robert,
>
> Why not implement it as a regular driver? If we ever want to implement
> a commandline control of the pwms via pwm0.dutyns=xx we'll need
> a struct device.

This is because in my own case, I need pwm to be registered before other devices
are probed. The trouble (in my case) is that for drivers/video/pxa.c, I have the
following call path :
 - pxafb_probe()
   -> pxafb_enable_controller()
     -> pxafb_backlight_power()
       -> mioa701_lcd_backlight()
          => 	struct pwm_device *pwm0 = pwm_request("pxa_pwm0");
		pwm_enable(pwm0);
		pwm_config(pwm0, 2000 * 1024, 4000 * 1024);

I'm a bit afraid that the pxafb driver will be probed first, before pwm_pxa, and
therefore the backlight setting won't work. I haven't found a clean way to
specify this dependency.

Cheers.

-- 
Robert

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  reply	other threads:[~2012-02-03 15:39 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-01-31  9:36 [PATCH] Add pwm core support Sascha Hauer
2012-02-01  8:20 ` Robert Jarzmik
2012-02-01 22:42 ` [PATCH] drivers/pwm: add PXA pulse width modulator controller Robert Jarzmik
2012-02-03  9:52   ` Sascha Hauer
2012-02-03 15:39     ` Robert Jarzmik [this message]
2012-02-08 15:26       ` Robert Jarzmik
2012-02-09  8:10         ` Sascha Hauer
2012-02-09 11:50           ` Robert Jarzmik
2012-02-09 13:44             ` Sascha Hauer
2012-02-09 14:30               ` Robert Jarzmik
2012-02-14 12:58             ` [PATCH V2 1/2] " Robert Jarzmik
2012-02-14 12:58               ` [PATCH V2 2/2] drivers/video: remove pxafb enable on load Robert Jarzmik
2012-02-15  8:32               ` [PATCH V2 1/2] drivers/pwm: add PXA pulse width modulator controller Sascha Hauer
2012-02-15 11:22                 ` Robert Jarzmik
2012-02-15 15:21                 ` Robert Jarzmik
2012-02-16  7:40                   ` Sascha Hauer
2012-02-16 18:23                     ` [PATCH V3 1/3] drivers/pwm: add duty_ns and period_ns to core pwm chip Robert Jarzmik
2012-02-16 18:23                       ` [PATCH V3 2/3] drivers/pwm: add PXA pulse width modulator controller Robert Jarzmik
2012-02-16 18:23                       ` [PATCH V3 3/3] drivers/video: remove pxafb enable on load Robert Jarzmik

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