From: Jingoo Han <jg1.han@samsung.com>
To: "'Lars-Peter Clausen'" <lars@metafoo.de>
Cc: "'Thierry Reding'" <thierry.reding@avionic-design.de>,
linux-kernel@vger.kernel.org,
"'Sascha Hauer'" <kernel@pengutronix.de>,
linux-arm-kernel@lists.infradead.org,
"'Dmitry Torokhov'" <dmitry.torokhov@gmail.com>,
linux-input@vger.kernel.org,
"'Bryan Wu'" <bryan.wu@canonical.com>,
"'Richard Purdie'" <rpurdie@rpsys.net>,
linux-leds@vger.kernel.org,
"'Florian Tobias Schandinat'" <FlorianSchandinat@gmx.de>,
linux-fbdev@vger.kernel.org,
"'Benoît Thébaudeau'" <benoit.thebaudeau@advansee.com>,
"'Jingoo Han'" <jg1.han@samsung.com>
Subject: Re: [PATCH] pwm: Call pwm_enable() before pwm_config()
Date: Thu, 30 Aug 2012 16:10:11 +0900 [thread overview]
Message-ID: <002001cd867e$7e964130$7bc2c390$%han@samsung.com> (raw)
In-Reply-To: <50364FA4.7000401@metafoo.de>
On Friday, August 24, 2012 12:44 AM, Lars-Peter Clausen wrote:
>
> On 08/23/2012 04:19 PM, Benoît Thébaudeau wrote:
> > Some PWM drivers enable the clock of the PWM peripheral in pwm_enable(). Hence,
> > for these drivers, a call to pwm_config() does not have any effect before
> > pwm_enable() has been called.
> >
> > This patch fixes the PWM users to make sure that they call pwm_enable() before
> > pwm_config().
> >
> > This fixes the first setting of brightness through sysfs that had no effect with
> > leds-pwm and the i.MX PWM driver.
>
> But isn't this a bug in the PWM peripheral driver? With this change the PWM
> will start with the old settings first. While this is not so much of a problem
> for a backlight (although it might cause a short flickering) it might cause
> problems for other applications, like using the PWM pin as a timing generator.
> In my opinion it's better to fix the PWM peripheral drivers which have this
> problem instead of trying to work around it in every user of the PWM API.
Hi Lars-Peter Clausen,
I think so.
It would be better to fix the PWM peripheral drivers.
Best regards,
Jingoo Han
>
> - Lars
> --
> To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
WARNING: multiple messages have this Message-ID (diff)
From: Jingoo Han <jg1.han@samsung.com>
To: linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] pwm: Call pwm_enable() before pwm_config()
Date: Thu, 30 Aug 2012 07:10:11 +0000 [thread overview]
Message-ID: <002001cd867e$7e964130$7bc2c390$%han@samsung.com> (raw)
In-Reply-To: <50364FA4.7000401@metafoo.de>
On Friday, August 24, 2012 12:44 AM, Lars-Peter Clausen wrote:
>
> On 08/23/2012 04:19 PM, Benoît Thébaudeau wrote:
> > Some PWM drivers enable the clock of the PWM peripheral in pwm_enable(). Hence,
> > for these drivers, a call to pwm_config() does not have any effect before
> > pwm_enable() has been called.
> >
> > This patch fixes the PWM users to make sure that they call pwm_enable() before
> > pwm_config().
> >
> > This fixes the first setting of brightness through sysfs that had no effect with
> > leds-pwm and the i.MX PWM driver.
>
> But isn't this a bug in the PWM peripheral driver? With this change the PWM
> will start with the old settings first. While this is not so much of a problem
> for a backlight (although it might cause a short flickering) it might cause
> problems for other applications, like using the PWM pin as a timing generator.
> In my opinion it's better to fix the PWM peripheral drivers which have this
> problem instead of trying to work around it in every user of the PWM API.
Hi Lars-Peter Clausen,
I think so.
It would be better to fix the PWM peripheral drivers.
Best regards,
Jingoo Han
>
> - Lars
> --
> To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
WARNING: multiple messages have this Message-ID (diff)
From: jg1.han@samsung.com (Jingoo Han)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] pwm: Call pwm_enable() before pwm_config()
Date: Thu, 30 Aug 2012 16:10:11 +0900 [thread overview]
Message-ID: <002001cd867e$7e964130$7bc2c390$%han@samsung.com> (raw)
In-Reply-To: <50364FA4.7000401@metafoo.de>
On Friday, August 24, 2012 12:44 AM, Lars-Peter Clausen wrote:
>
> On 08/23/2012 04:19 PM, Beno?t Th?baudeau wrote:
> > Some PWM drivers enable the clock of the PWM peripheral in pwm_enable(). Hence,
> > for these drivers, a call to pwm_config() does not have any effect before
> > pwm_enable() has been called.
> >
> > This patch fixes the PWM users to make sure that they call pwm_enable() before
> > pwm_config().
> >
> > This fixes the first setting of brightness through sysfs that had no effect with
> > leds-pwm and the i.MX PWM driver.
>
> But isn't this a bug in the PWM peripheral driver? With this change the PWM
> will start with the old settings first. While this is not so much of a problem
> for a backlight (although it might cause a short flickering) it might cause
> problems for other applications, like using the PWM pin as a timing generator.
> In my opinion it's better to fix the PWM peripheral drivers which have this
> problem instead of trying to work around it in every user of the PWM API.
Hi Lars-Peter Clausen,
I think so.
It would be better to fix the PWM peripheral drivers.
Best regards,
Jingoo Han
>
> - Lars
> --
> To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in
> the body of a message to majordomo at vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
next prev parent reply other threads:[~2012-08-30 7:10 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <322770447.2755463.1345727876098.JavaMail.root@advansee.com>
2012-08-23 13:36 ` [BUG] leds-pwm: First setting of brightness does nothing Benoît Thébaudeau
2012-08-23 13:36 ` Benoît Thébaudeau
2012-08-23 14:19 ` [PATCH] pwm: Call pwm_enable() before pwm_config() Benoît Thébaudeau
2012-08-23 14:19 ` Benoît Thébaudeau
2012-08-23 14:19 ` Benoît Thébaudeau
2012-08-23 14:19 ` Benoît Thébaudeau
2012-08-23 15:43 ` Lars-Peter Clausen
2012-08-23 15:43 ` Lars-Peter Clausen
2012-08-23 15:43 ` Lars-Peter Clausen
2012-08-23 16:57 ` Benoît Thébaudeau
2012-08-23 16:57 ` Benoît Thébaudeau
2012-08-23 16:57 ` Benoît Thébaudeau
2012-08-23 16:57 ` Benoît Thébaudeau
2012-08-23 17:12 ` Lars-Peter Clausen
2012-08-23 17:12 ` Lars-Peter Clausen
2012-08-23 17:12 ` Lars-Peter Clausen
2012-08-23 17:19 ` Lars-Peter Clausen
2012-08-23 17:19 ` Lars-Peter Clausen
2012-08-23 17:19 ` Lars-Peter Clausen
2012-08-23 19:04 ` Thierry Reding
2012-08-23 19:04 ` Thierry Reding
2012-08-23 19:04 ` Thierry Reding
2012-09-20 19:05 ` Mark Brown
2012-09-20 19:05 ` Mark Brown
2012-09-20 19:05 ` Mark Brown
2012-08-23 19:11 ` Thierry Reding
2012-08-23 19:11 ` Thierry Reding
2012-08-23 19:11 ` Thierry Reding
2012-08-23 20:58 ` [PATCH] pwm-imx: Fix config / enable / disable Benoît Thébaudeau
2012-08-23 21:03 ` Benoît Thébaudeau
2012-08-23 21:03 ` Benoît Thébaudeau
2012-08-23 21:03 ` Benoît Thébaudeau
2012-08-28 7:37 ` Sascha Hauer
2012-08-28 7:37 ` Sascha Hauer
2012-08-28 7:37 ` Sascha Hauer
2012-08-28 7:37 ` Sascha Hauer
2012-09-20 19:03 ` [PATCH] pwm: Call pwm_enable() before pwm_config() Mark Brown
2012-09-20 19:03 ` Mark Brown
2012-09-20 19:03 ` Mark Brown
2012-08-30 7:10 ` Jingoo Han [this message]
2012-08-30 7:10 ` Jingoo Han
2012-08-30 7:10 ` Jingoo Han
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