From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jingoo Han Date: Thu, 30 Aug 2012 07:10:11 +0000 Subject: Re: [PATCH] pwm: Call pwm_enable() before pwm_config() Message-Id: <002001cd867e$7e964130$7bc2c390$%han@samsung.com> List-Id: References: <217877237.2758643.1345731587941.JavaMail.root@advansee.com> <50364FA4.7000401@metafoo.de> In-Reply-To: <50364FA4.7000401@metafoo.de> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit To: linux-arm-kernel@lists.infradead.org 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