On Tue, Jun 04, 2013 at 11:23:07PM +0200, Simon Guinot wrote: > On Tue, Jun 04, 2013 at 08:52:12AM +0200, Arnaud Ebalard wrote: > > Hi Simon, > > > > Simon Guinot <simon.guinot@xxxxxxxxxxxx> writes: > > > > > On Sat, Jun 01, 2013 at 07:26:54PM +0200, Arnaud Ebalard wrote: > > >> Hi Simon and Guenter, > > >> > > >> Simon Guinot <simon.guinot@xxxxxxxxxxxx> writes: > > >> > > >> > On Tue, May 28, 2013 at 12:03:14AM +0200, Arnaud Ebalard wrote: > > >> >> > > >> >> Signed-off-by: Arnaud Ebalard <arno@xxxxxxxxxxxx> > > >> >> --- > > >> >> drivers/hwmon/Kconfig | 10 + > > >> >> drivers/hwmon/Makefile | 1 + > > >> >> drivers/hwmon/g762.c | 1012 ++++++++++++++++++++++++++++++++++++ > > >> >> include/linux/platform_data/g762.h | 54 ++ > > >> >> 4 files changed, 1077 insertions(+) > > >> >> create mode 100644 drivers/hwmon/g762.c > > >> >> create mode 100644 include/linux/platform_data/g762.h > > >> > > > >> > Hi Arnaud, > > >> > > > >> > After more tests on my 2Big Network v2 board, it appears that the fan > > >> > doesn't rotate when PWM mode (the preferred operating mode for this > > >> > board) is selected. Nevertheless, DC mode is usable (even if not ideal > > >> > given the hardware). After some investigations I noticed that an extra > > >> > initialization is needed to enable PWM mode on my board: the set_cnt > > >> > register must be set to 0 while the default value is 0xff. Is that > > >> > specific to my hardware ? Is PWM mode working on your ReadyNAS with > > >> > the default set_cnt value ? > > >> > > >> First, thanks for testing this! > > >> > > >> Regarding your problem, I first started by booting current version of my > > >> driver on the Duo v2 w/o touching chip registers (only clock reference > > >> value). This way, I inherit the values installed by (NETGEAR's) u-boot: > > >> > > >> $ for k in fan* pwm* ; do echo -n "$k:" ; echo `cat $k `; done > > >> fan1_alarm:0 > > >> fan1_div:2 > > >> fan1_fault:0 > > >> fan1_input:1807 > > >> fan1_target:1807 > > >> pwm1:221 > > >> pwm1_enable:2 /* closed-loop, i.e. config is done via set_cnt */ > > >> pwm1_mode:1 /* PWM mode */ > > > > > > Sorry, I realize that I have not been very accurate in my description of > > > the problem: The fan doesn't rotate when PWM _and_ open-loop control are > > > selected. On the 2Big2 board, 2 wires are used to drive the fan. > > > > > > Then with pwm1_mode=1, pwm1_enable=1 and set_cnt=0xff (default value), > > > nothing happen whatever the value I write in pwm1. > > > > After boot, with set_cnt and set_out untouched by me (set_cnt set to > > 0x5a by u-boot, i.e. 255-0x5a read on pwm1): > > > > fan1_alarm:0 > > fan1_div:1 > > fan1_fault:0 > > fan1_input:1365 > > fan1_target:1365 > > pwm1:0 /* set_out is 0 (considering fan1_target, > > set_cnt is 0x5a)*/ > > pwm1_enable:2 /* closed-loop */ > > pwm1_mode:0 /* DC mode */ > > > > # echo 1 > pwm1_mode /* PWM mode */ # fan rotates > > # echo 1 > pwm1_enable /* open-loop */ # fan stops rotating > > > > At that point we have: > > > > fan1_alarm:0 > > fan1_div:1 > > fan1_fault:0 > > fan1_input:0 > > fan1_target:1365 > > pwm1:0 /* set_out is 0, set_cnt is still 0x5a */ > > pwm1_enable:1 > > pwm1_mode:1 > > > > Then: > > > > # echo 100 > pwm1 # fan rotates > > OK you are lucky. Your bootloader initialize set_cnt with 0x5a. Mine > don't and it is precisely the issue: set_cnt is still 0xff (the default > value) when the driver controls the fan. > > Please, could you try open-loop mode with set_cnt set to 0xff ? Maybe > you can enforce this value for the test purpose ? > > If you observe the same behaviour than me, then could modify the driver > to ensure that set_cnt is not 0xff when open-loop mode is selected ? > Maybe by systematically setting a different value (as 0) ? > I think it would make sense to set it to 0 when open-loop mode is selected, or at least to set it to a value != 0xff. Question would be if the value has any meaning in open loop mode, other than to enable/disable fan control entirely. Thanks, Guenter > > > > > > > By testing, I have discovered that writing 0 into set_cnt allows to work > > > around the issue. I can do this by using the closed-loop control: > > > pwm1_mode=1, pwm1_enable=2 and pwm=255. Now, set_cnt worths 0 and if I > > > switch back to open-loop control, all works as expected. > > > > > > Can you try open-loop control and PWM mode with your board ? I wonder if > > > this issue is specific to the 2Big2 hardware. > > > > AFAICT, set_cnt has never been set to 0 in my test and PWM+open-loop > > works as expected, i.e. just by setting a non-zero value in set_out. > > Tell me if I missed something or if you want me to perform another > > test. > > Actually, I have only problems when set_cnt worths 0xff. Please, could > you try the tests mentioned above ? > > Thanks in advance, > > Simon > > > > > Cheers, > > > > a+ > > > > _______________________________________________ > > linux-arm-kernel mailing list > > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
