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) ? > > > > 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
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