| Message ID | 1466204089-17030-5-git-send-email-pali.rohar@gmail.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
Tested on a Dell Precision M3800. After applying this patch, the machine doesn't freeze for a couple of seconds on module load and on each sensors (lm_sensors) call anymore. It now just freezes once, when running sensors for the first time, and that's it. It was not possible to read correct RPM values using sensors before, because the fans were running at maximum speed, when the freeze occured. I can now read RPM values correctly and the machine doesn't annoy me with freezing up on boot anymore. Tested-by: Tolga Cakir <cevelnet@gmail.com> 2016-06-18 0:54 GMT+02:00 Pali Rohár <pali.rohar@gmail.com>: > On more Dell machines (e.g. Dell Precision M3800) fan_type() call is too > expensive (CPU is too long in SMM mode) and cause kernel to hang. This is > bug in Dell SMM or BIOS. > > This patch caches type for each fan (as it should not change) and changes > the way how fan presense is detected. First it try function fan_status() > as was before commit f989e55452c7 ("i8k: Add support for fan labels"). And > if that fails fallback to fan_type(). *_status() functions can fail in case > fan is not currently accessible (e.g. present on GPU which is currently > turned off). > > Reported-by: Tolga Cakir <cevelnet@gmail.com> > Signed-off-by: Pali Rohár <pali.rohar@gmail.com> > Link: https://bugzilla.kernel.org/show_bug.cgi?id=112021 > Cc: stable@vger.kernel.org # v4.0+, will need backport > --- > drivers/hwmon/dell-smm-hwmon.c | 25 ++++++++++++++++++++----- > 1 file changed, 20 insertions(+), 5 deletions(-) > > diff --git a/drivers/hwmon/dell-smm-hwmon.c b/drivers/hwmon/dell-smm-hwmon.c > index 4bbc587..2ac87d5 100644 > --- a/drivers/hwmon/dell-smm-hwmon.c > +++ b/drivers/hwmon/dell-smm-hwmon.c > @@ -238,7 +238,7 @@ 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, }; > > @@ -249,6 +249,17 @@ 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. > */ > @@ -782,13 +793,17 @@ 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 or type is OK */ > + err = i8k_get_fan_status(0); > + if (err < 0) > + err = i8k_get_fan_type(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 or type is OK */ > + err = i8k_get_fan_status(1); > + if (err < 0) > + err = i8k_get_fan_type(1); > if (err >= 0) > i8k_hwmon_flags |= I8K_HWMON_HAVE_FAN2; > > -- > 1.7.9.5 > -- To unsubscribe from this list: send the line "unsubscribe linux-hwmon" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/hwmon/dell-smm-hwmon.c b/drivers/hwmon/dell-smm-hwmon.c index 4bbc587..2ac87d5 100644 --- a/drivers/hwmon/dell-smm-hwmon.c +++ b/drivers/hwmon/dell-smm-hwmon.c @@ -238,7 +238,7 @@ 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, }; @@ -249,6 +249,17 @@ 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. */ @@ -782,13 +793,17 @@ 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 or type is OK */ + err = i8k_get_fan_status(0); + if (err < 0) + err = i8k_get_fan_type(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 or type is OK */ + err = i8k_get_fan_status(1); + if (err < 0) + err = i8k_get_fan_type(1); if (err >= 0) i8k_hwmon_flags |= I8K_HWMON_HAVE_FAN2;
On more Dell machines (e.g. Dell Precision M3800) fan_type() call is too expensive (CPU is too long in SMM mode) and cause kernel to hang. This is bug in Dell SMM or BIOS. This patch caches type for each fan (as it should not change) and changes the way how fan presense is detected. First it try function fan_status() as was before commit f989e55452c7 ("i8k: Add support for fan labels"). And if that fails fallback to fan_type(). *_status() functions can fail in case fan is not currently accessible (e.g. present on GPU which is currently turned off). Reported-by: Tolga Cakir <cevelnet@gmail.com> Signed-off-by: Pali Rohár <pali.rohar@gmail.com> Link: https://bugzilla.kernel.org/show_bug.cgi?id=112021 Cc: stable@vger.kernel.org # v4.0+, will need backport --- drivers/hwmon/dell-smm-hwmon.c | 25 ++++++++++++++++++++----- 1 file changed, 20 insertions(+), 5 deletions(-)