On Sunday 22 May 2016 02:19:48 Guenter Roeck wrote: > On 05/21/2016 07:46 AM, Pali Rohár wrote: > > On more Dell machines (e.g. Dell Precision M3800) > > I8K_SMM_GET_FAN_TYPE call is too expensive (CPU is too long in SMM > > mode) and cause kernel to hang. This patch cache type for each fan > > (as it should not change) and change the way how fan presense is > > detected. It revert and use function fan_status() as was before > > commit f989e55452c7 ("i8k: Add support for fan labels"). > > > > Moreover, kernel hangs for 2 - 3 seconds only sometimes and only on > > some Dell machines. When kernel hangs fan speed is at max. So it > > was hard to debug and bisect where is root of this problem. It > > looks like this is bug in Dell BIOS which implement fan type SMM > > code... and there is no way how to fix it in kernel. > > > > Signed-off-by: Pali Rohár <pali.rohar@xxxxxxxxx> > > Reviewed-by: Jean Delvare <jdelvare@xxxxxxx> > > Reported-and-tested-by: Tolga Cakir <cevelnet@xxxxxxxxx> > > Fixes: f989e55452c7 ("i8k: Add support for fan labels") > > Link: https://bugzilla.kernel.org/show_bug.cgi?id=112021 > > Link: https://bugzilla.kernel.org/show_bug.cgi?id=100121 > > Cc: stable@xxxxxxxxxxxxxxx # v4.0+, will need backport > > Should this patch be applied, or do you wait for more testing ? I would like to hear some confirmation from people with affected machine. > Guenter > > > --- > > > > drivers/hwmon/dell-smm-hwmon.c | 21 ++++++++++++++++----- > > 1 file changed, 16 insertions(+), 5 deletions(-) > > > > --- > > > > Hi! > > > > Jan C Peters, Thorsten Leemhuis, David Santamaría Rogado, Peter > > Saunderson and others, can you test this patch if it fixes your > > freeze problem at boottime and when using "sensors" program? > > > > I need to know if this patch fixes problem on Dell Studio XPS 8000 > > and Dell Studio XPS 8100 machines, so we can revert git commits: > > > > 6220f4ebd7b4 ("hwmon: (dell-smm) Blacklist Dell Studio XPS 8000") > > a4b45b25f18d ("hwmon: (dell-smm) Blacklist Dell Studio XPS 8100") > > > > diff --git a/drivers/hwmon/dell-smm-hwmon.c > > b/drivers/hwmon/dell-smm-hwmon.c index c43318d..577445f 100644 > > --- a/drivers/hwmon/dell-smm-hwmon.c > > +++ b/drivers/hwmon/dell-smm-hwmon.c > > @@ -235,7 +235,7 @@ static int i8k_get_fan_speed(int fan) > > > > /* > > > > * Read the fan type. > > */ > > > > -static int i8k_get_fan_type(int fan) > > +static int _i8k_get_fan_type(int fan) > > > > { > > > > struct smm_regs regs = { .eax = I8K_SMM_GET_FAN_TYPE, }; > > > > @@ -243,6 +243,17 @@ static int i8k_get_fan_type(int fan) > > > > return i8k_smm(®s) ? : regs.eax & 0xff; > > > > } > > > > +static int i8k_get_fan_type(int fan) > > +{ > > + /* I8K_SMM_GET_FAN_TYPE SMM call is expensive, so cache values */ > > + static int types[2] = { INT_MIN, INT_MIN }; > > + > > + if (types[fan] == INT_MIN) > > + types[fan] = _i8k_get_fan_type(fan); > > + > > + return types[fan]; > > +} > > + > > > > /* > > > > * Read the fan nominal rpm for specific fan speed. > > */ > > > > @@ -767,13 +778,13 @@ static int __init i8k_init_hwmon(void) > > > > if (err >= 0) > > > > i8k_hwmon_flags |= I8K_HWMON_HAVE_TEMP4; > > > > - /* First fan attributes, if fan type is OK */ > > - err = i8k_get_fan_type(0); > > + /* First fan attributes, if fan status is OK */ > > + err = i8k_get_fan_status(0); > > > > if (err >= 0) > > > > i8k_hwmon_flags |= I8K_HWMON_HAVE_FAN1; > > > > - /* Second fan attributes, if fan type is OK */ > > - err = i8k_get_fan_type(1); > > + /* Second fan attributes, if fan status is OK */ > > + err = i8k_get_fan_status(1); > > > > if (err >= 0) > > > > i8k_hwmon_flags |= I8K_HWMON_HAVE_FAN2; -- Pali Rohár pali.rohar@xxxxxxxxx
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