On Sun, 2017-01-08 at 14:44 +0100, Hans de Goede wrote: > One some systems the punit accesses the pmic to change various > voltages > through the same bus as other kernel drivers use for e.g. battery > monitoring. > > If a driver sends requests to the punit which require the punit to > access > the pmic bus while another driver is also accessing the pmic bus > various > bad things happen. > > This commit adds a mutex to protect the punit against simultaneous > accesses > and 2 functions to lock / unlock this mutex. > > Note on these systems the i2c-bus driver will request a sempahore from > the > punit for exclusive access to the pmic bus when i2c drivers are > accessing > it, but this does not appear to be sufficient, we still need to avoid > making certain punit requests during the access window to avoid > problems. I'm fine with the patch, but please spell P-Unit PMIC Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> > > BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=155241 > Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> > Tested-by: tagorereddy <tagore.chandan@xxxxxxxxx> > --- > arch/x86/include/asm/iosf_mbi.h | 31 > +++++++++++++++++++++++++++++++ > arch/x86/platform/intel/iosf_mbi.c | 13 +++++++++++++ > 2 files changed, 44 insertions(+) > > diff --git a/arch/x86/include/asm/iosf_mbi.h > b/arch/x86/include/asm/iosf_mbi.h > index b41ee16..91f5d16 100644 > --- a/arch/x86/include/asm/iosf_mbi.h > +++ b/arch/x86/include/asm/iosf_mbi.h > @@ -88,6 +88,33 @@ int iosf_mbi_write(u8 port, u8 opcode, u32 offset, > u32 mdr); > */ > int iosf_mbi_modify(u8 port, u8 opcode, u32 offset, u32 mdr, u32 > mask); > > +/** > + * iosf_mbi_punit_lock() - Lock the punit mutex > + * > + * One some systems the punit accesses the pmic to change various > voltages > + * through the same bus as other kernel drivers use for e.g. battery > monitoring. > + * > + * If a driver sends requests to the punit which require the punit to > access the > + * pmic bus while another driver is also accessing the pmic bus > various bad > + * things happen. > + * > + * To avoid these problems this function must be called before > accessing the > + * punit or the pmic, be it through iosf_mbi* functions or through > other means. > + * > + * Note on these systems the i2c-bus driver will request a sempahore > from the > + * punit for exclusive access to the pmic bus when i2c drivers are > accessing it, > + * but this does not appear to be sufficient, we still need to avoid > making > + * certain punit requests during the access window to avoid problems. > + * > + * This function locks a mutex, as such it may sleep. > + */ > +void iosf_mbi_punit_lock(void); > + > +/** > + * iosf_mbi_punit_unlock() - Unlock the punit mutex > + */ > +void iosf_mbi_punit_unlock(void); > + > #else /* CONFIG_IOSF_MBI is not enabled */ > static inline > bool iosf_mbi_available(void) > @@ -115,6 +142,10 @@ int iosf_mbi_modify(u8 port, u8 opcode, u32 > offset, u32 mdr, u32 mask) > WARN(1, "IOSF_MBI driver not available"); > return -EPERM; > } > + > +static inline void iosf_mbi_punit_lock(void) {} > +static inline void iosf_mbi_punit_unlock(void) {} > + > #endif /* CONFIG_IOSF_MBI */ > > #endif /* IOSF_MBI_SYMS_H */ > diff --git a/arch/x86/platform/intel/iosf_mbi.c > b/arch/x86/platform/intel/iosf_mbi.c > index edf2c54..75d8135 100644 > --- a/arch/x86/platform/intel/iosf_mbi.c > +++ b/arch/x86/platform/intel/iosf_mbi.c > @@ -34,6 +34,7 @@ > > static struct pci_dev *mbi_pdev; > static DEFINE_SPINLOCK(iosf_mbi_lock); > +static DEFINE_MUTEX(iosf_mbi_punit_mutex); > > static inline u32 iosf_mbi_form_mcr(u8 op, u8 port, u8 offset) > { > @@ -190,6 +191,18 @@ bool iosf_mbi_available(void) > } > EXPORT_SYMBOL(iosf_mbi_available); > > +void iosf_mbi_punit_lock(void) > +{ > + mutex_lock(&iosf_mbi_punit_mutex); > +} > +EXPORT_SYMBOL(iosf_mbi_punit_lock); > + > +void iosf_mbi_punit_unlock(void) > +{ > + mutex_unlock(&iosf_mbi_punit_mutex); > +} > +EXPORT_SYMBOL(iosf_mbi_punit_unlock); > + > #ifdef CONFIG_IOSF_MBI_DEBUG > static u32 dbg_mdr; > static u32 dbg_mcr; -- Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> Intel Finland Oy -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
