From mboxrd@z Thu Jan 1 00:00:00 1970 From: Guenter Roeck Date: Wed, 03 Dec 2014 05:29:56 +0000 Subject: Re: [lm-sensors] adt7475 driver: PWM invert configuration bit Message-Id: <547E9FD4.5070203@roeck-us.net> List-Id: References: <20141203041242.GD11971@cumulusnetworks.com> In-Reply-To: <20141203041242.GD11971@cumulusnetworks.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: lm-sensors@vger.kernel.org On 12/02/2014 08:12 PM, Curt Brune wrote: > Hello, > > I have a system where I need to change the "PWM invert" bit (bit 4) in > the PWM configuration register (offset 0x5C). The description of this > configuration bit from the data sheet: > > This bit inverts the PWM output. The default is 0, which corresponds > to a logic high output for 100% duty cycle. Setting this bit to 1 > inverts the PWM output, so 100% duty cycle corresponds to a logic > low output. > > I noticed the adt7475.c driver does not expose this bit in sysfs. > Before hacking away I am curious to know why this configuration bit is > not exposed already. Some reasons I could think of: > > - expect the power on default to be correct > - expect some other software (boot loader or BIOS) has already set it > - just never needed it > > If it was just never needed then I am proposing to add 3 read/write > files to sysfs: > > pwm1_invert > pwm2_invert > pwm3_invert > > The values of 0 and 1 would have the same meaning as the "PWM invert" > bit (bit 4) in the PWM configuration register (offset 0x5C). Any > other value would be treated as -EINVAL. > This is usually a system attribute, not something to configure at runtime. As such, expectation would be that it is set either with platform data and/or with a devicetree property, not with a sysfs attribute. Guenter _______________________________________________ lm-sensors mailing list lm-sensors@lm-sensors.org http://lists.lm-sensors.org/mailman/listinfo/lm-sensors