One some systems the P-Unit 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 P-Unit which require the P-Unit 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 P-Unit 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 P-Unit 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 P-Unit requests during the access window to avoid problems. BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=155241 Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> Tested-by: tagorereddy <tagore.chandan@xxxxxxxxx> Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> --- Changes in v2: -Rename iosf_mbi_punit_lock/_unlock to _acquire/_release rename -Spelling: P-Unit, PMIC --- 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..f6119d0 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_acquire() - Acquire access to the P-Unit + * + * One some systems the P-Unit 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 P-Unit which require the P-Unit 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 + * P-Unit 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 + * P-Unit 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 P-Unit requests during the access window to avoid problems. + * + * This function locks a mutex, as such it may sleep. + */ +void iosf_mbi_punit_acquire(void); + +/** + * iosf_mbi_punit_release() - Release access to the P-Unit + */ +void iosf_mbi_punit_release(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_acquire(void) {} +static inline void iosf_mbi_punit_release(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..ed24fa9f 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_acquire(void) +{ + mutex_lock(&iosf_mbi_punit_mutex); +} +EXPORT_SYMBOL(iosf_mbi_punit_acquire); + +void iosf_mbi_punit_release(void) +{ + mutex_unlock(&iosf_mbi_punit_mutex); +} +EXPORT_SYMBOL(iosf_mbi_punit_release); + #ifdef CONFIG_IOSF_MBI_DEBUG static u32 dbg_mdr; static u32 dbg_mcr; -- 2.9.3 _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
