From mboxrd@z Thu Jan 1 00:00:00 1970 From: Guenter Roeck Date: Sun, 01 Dec 2013 17:20:35 +0000 Subject: Re: [lm-sensors] w83l786ng driver bug, questions, and 1st round patch Message-Id: <529B6FE3.5010606@roeck-us.net> List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: lm-sensors@vger.kernel.org On 12/01/2013 01:38 AM, Jean Delvare wrote: [ ... ] > >> # Note the power up default is actually mode 4, which is even more >> # confusing (sysfs would tell you we're in mode 3, until you first >> # touch the mode, then it would lock back into mode 1 behavior. >> # For the above I made things less confusing for the reader by >> # first forcing mode 1.) > > Mode "FAN_SET" is problematic on its own, independent of the bug you > found and fixed. There is no room for it in our standard sysfs > interface. It's not really an automatic fan speed mode so it shouldn't > have value >= 2. The closest standard mode would be 0, except that 0 is > supposed to mean "100%", not "some arbitrary initial value". Well, we > could write 0xf to register 0x90 bits 3..0 (assuming they are writable > as the datasheet says) to force the 100% but then this would prevent > the user from returning to the initial state, plus I'm not sure what > would happen at suspend/resume or reboot. > > OTOH, if we stick to value 4 for this mode, then there's no reason to > not let the user switch back to it. Supporting it would be truly > trivial. > > Another possibility would be to hide this mode, by transparently > switching to the equivalent speed in manual control mode when the > driver is loaded. Then only modes 1, 2 and 3 would be visible to the > user. To be honest I'm not sure why the chip maker didn't implement it > this way in the first place. I think this option has my preference. > Guenter, what do you think? Do we have any precedent? > Hi Jean, The asc7621 driver uses pwmX_enable=0 to turn the fan off, and %5 to set it to full speed. I would not necessarily take that as good example, though. Your proposal to hide FAN_SET underneath mode 1 would be one possibility. I would also not mind using pwmX_enable=0 ('disabled') for that purpose, ie let the fan speed revert to the pre-programmed speed instead of 100% if it is set. While not following the ABI to the letter, one could argue that it follows the idea. Thanks, Guenter _______________________________________________ lm-sensors mailing list lm-sensors@lm-sensors.org http://lists.lm-sensors.org/mailman/listinfo/lm-sensors