Re: [PATCH 1/3] x86: baytrail/cherrytrail: Rework and move P-Unit PMIC bus semaphore code

[Hans de Goede]

Hi,

On 18-10-18 09:29, Rafael J. Wysocki wrote:
> On Sun, Sep 23, 2018 at 4:45 PM Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
> > On some BYT/CHT systems the SoC's P-Unit shares the I2C bus with the
> > kernel. The P-Unit has a semaphore for the PMIC bus which we can take to
> > block it from accessing the shared bus while the kernel wants to access it.
> >
> > Currently we have the I2C-controller driver acquiring and releasing the
> > semaphore around each I2C transfer. There are 2 problems with this:
> >
> > 1) PMIC accesses often come in the form of a read-modify-write on one of
> > the PMIC registers, we currently release the P-Unit's PMIC bus semaphore
> > between the read and the write. If the P-Unit modifies the register during
> > this window?, then we end up overwriting the P-Unit's changes.
> > I believe that this is mostly an academic problem, but I'm not sure.
> >
> > 2) To safely access the shared I2C bus, we need to do 3 things:
> > a) Notify the GPU driver that we are starting a window in which it may not
> > access the P-Unit, since the P-Unit seems to ignore the semaphore for
> > explicit power-level requests made by the GPU driver
> > b) Make a pm_qos request to force all CPU cores out of C6/C7 since entering
> > C6/C7 while we hold the semaphore hangs the SoC
> > c) Finally take the P-Unit's PMIC bus semaphore
> > All 3 these steps together are somewhat expensive, so ideally if we have
> > a bunch of i2c transfers grouped together we only do this once for the
> > entire group.
> >
> > Taking the read-modify-write on a PMIC register as example then ideally we
> > would only do all 3 steps once at the beginning and undo all 3 steps once
> > at the end.
> >
> > For this we need to be able to take the semaphore from within e.g. the PMIC
> > opregion driver, yet we do not want to remove the taking of the semaphore
> > from the I2C-controller driver, as that is still necessary to protect many
> > other code-paths leading to accessing the shared I2C bus.
> >
> > This means that we first have the PMIC driver acquire the semaphore and
> > then have the I2C controller driver trying to acquire it again.
> >
> > To make this possible this commit does the following:
> >
> > 1) Move the semaphore code from being private to the I2C controller driver
> > into the generic iosf_mbi code, which already has other code to deal with
> > the shared bus so that it can be accessed outside of the I2C bus driver.
> >
> > 2) Rework the code so that it can be called multiple times nested, while
> > still blocking I2C accesses while e.g. the GPU driver has indicated the
> > P-Unit needs the bus through a iosf_mbi_punit_acquire() call.
> >
> > Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
>
> If there are no objections or concerns regarding this patch, I'm
> inclined to take the entire series including it.

In that case let me send out a v4, with the following chunk added to the
2nd patch:

--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -515,7 +515,7 @@ config CRC_PMIC_OPREGION

 config XPOWER_PMIC_OPREGION
        bool "ACPI operation region support for XPower AXP288 PMIC"
-       depends on MFD_AXP20X_I2C
+       depends on MFD_AXP20X_I2C && IOSF_MBI
        help
          This config adds ACPI operation region support for XPower AXP288 PMIC.

This is necessary to avoid compilation issues on non x86 systems (where the
asm/iosf_mbi.h header is not available) and on x86 systems in case
IOSF_MBI support is not enabled there.  Note that the AXP288 PMIC is
connected through the LPSS i2c controller, so either we have IOSF_MBI support
selected through the X86_INTEL_LPSS option, or we have a kernel where the
opregion will never work anyways.

Regards,

Hans






> > ---
> > Note this commit deliberately limits the i2c-designware changes to
> > only touch i2c-designware-baytrail.c, deliberately not doing some cleanups
> > which become possible after removing the semaphore code from the
> > i2c-designmware code. This is done so that this commit can be merged
> > through the x86 tree without causing conflicts in the i2c tree.
> >
> > The cleanups to the i2c-designware tree will be done in a follow up
> > patch which can be merged once this commit is in place.
> > ---
> >   arch/x86/include/asm/iosf_mbi.h              |  39 +++--
> >   arch/x86/platform/intel/iosf_mbi.c           | 161 +++++++++++++++++--
> >   drivers/i2c/busses/i2c-designware-baytrail.c | 125 +-------------
> >   3 files changed, 180 insertions(+), 145 deletions(-)
> >
> > diff --git a/arch/x86/include/asm/iosf_mbi.h b/arch/x86/include/asm/iosf_mbi.h
> > index 3de0489deade..5270ff39b9af 100644
> > --- a/arch/x86/include/asm/iosf_mbi.h
> > +++ b/arch/x86/include/asm/iosf_mbi.h
> > @@ -105,8 +105,10 @@ int iosf_mbi_modify(u8 port, u8 opcode, u32 offset, u32 mdr, u32 mask);
> >    * 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.
> > + * Call this function before sending requests to the P-Unit which may make it
> > + * access the PMIC, be it through iosf_mbi* functions or through other means.
> > + * This function will block all kernel access to the PMIC I2C bus, so that the
> > + * P-Unit can safely access the PMIC over the shared I2C bus.
> >    *
> >    * 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
> > @@ -122,6 +124,31 @@ void iosf_mbi_punit_acquire(void);
> >    */
> >   void iosf_mbi_punit_release(void);
> >
> > +/**
> > + * iosf_mbi_block_punit_i2c_access() - Block P-Unit accesses to the PMIC bus
> > + *
> > + * Call this function to block P-Unit access to the PMIC I2C bus, so that the
> > + * kernel can safely access the PMIC over the shared I2C bus.
> > + *
> > + * This function acquires the P-Unit bus semaphore and notifies
> > + * pmic_bus_access_notifier listeners that they may no longer access the
> > + * P-Unit in a way which may cause it to access the shared I2C bus.
> > + *
> > + * Note this function may be called multiple times and the bus will not
> > + * be released until iosf_mbi_unblock_punit_i2c_access() has been called the
> > + * same amount of times.
> > + *
> > + * Return: Nonzero on error
> > + */
> > +int iosf_mbi_block_punit_i2c_access(void);
> > +
> > +/*
> > + * iosf_mbi_unblock_punit_i2c_access() - Release PMIC I2C bus block
> > + *
> > + * Release i2c access block gotten through iosf_mbi_block_punit_i2c_access().
> > + */
> > +void iosf_mbi_unblock_punit_i2c_access(void);
> > +
> >   /**
> >    * iosf_mbi_register_pmic_bus_access_notifier - Register PMIC bus notifier
> >    *
> > @@ -158,14 +185,6 @@ int iosf_mbi_unregister_pmic_bus_access_notifier(struct notifier_block *nb);
> >   int iosf_mbi_unregister_pmic_bus_access_notifier_unlocked(
> >          struct notifier_block *nb);
> >
> > -/**
> > - * iosf_mbi_call_pmic_bus_access_notifier_chain - Call PMIC bus notifier chain
> > - *
> > - * @val: action to pass into listener's notifier_call function
> > - * @v: data pointer to pass into listener's notifier_call function
> > - */
> > -int iosf_mbi_call_pmic_bus_access_notifier_chain(unsigned long val, void *v);
> > -
> >   /**
> >    * iosf_mbi_assert_punit_acquired - Assert that the P-Unit has been acquired.
> >    */
> > diff --git a/arch/x86/platform/intel/iosf_mbi.c b/arch/x86/platform/intel/iosf_mbi.c
> > index 6f37a2137a79..5623a315f004 100644
> > --- a/arch/x86/platform/intel/iosf_mbi.c
> > +++ b/arch/x86/platform/intel/iosf_mbi.c
> > @@ -18,12 +18,14 @@
> >    * enumerate the device using PCI.
> >    */
> >
> > +#include <linux/delay.h>
> >   #include <linux/module.h>
> >   #include <linux/init.h>
> >   #include <linux/spinlock.h>
> >   #include <linux/pci.h>
> >   #include <linux/debugfs.h>
> >   #include <linux/capability.h>
> > +#include <linux/pm_qos.h>
> >
> >   #include <asm/iosf_mbi.h>
> >
> > @@ -34,8 +36,8 @@
> >
> >   static struct pci_dev *mbi_pdev;
> >   static DEFINE_SPINLOCK(iosf_mbi_lock);
> > -static DEFINE_MUTEX(iosf_mbi_punit_mutex);
> > -static BLOCKING_NOTIFIER_HEAD(iosf_mbi_pmic_bus_access_notifier);
> > +
> > +/**************** Generic iosf_mbi access helpers ****************/
> >
> >   static inline u32 iosf_mbi_form_mcr(u8 op, u8 port, u8 offset)
> >   {
> > @@ -192,6 +194,30 @@ bool iosf_mbi_available(void)
> >   }
> >   EXPORT_SYMBOL(iosf_mbi_available);
> >
> > +/*
> > + **************** PUNIT/kernel shared i2c bus arbritration ****************
> > + *
> > + * Some Bay Trail and Cherry Trail devices have the PUNIT and us (the kernel)
> > + * share a single I2C bus to the PMIC. Below are helpers to arbitrate the
> > + * accesses between the kernel and the PUNIT.
> > + *
> > + * See arch/x86/include/asm/iosf_mbi.h for kernel-doc text for each function.
> > + */
> > +
> > +#define SEMAPHORE_TIMEOUT              500
> > +#define PUNIT_SEMAPHORE_BYT            0x7
> > +#define PUNIT_SEMAPHORE_CHT            0x10e
> > +#define PUNIT_SEMAPHORE_BIT            BIT(0)
> > +#define PUNIT_SEMAPHORE_ACQUIRE                BIT(1)
> > +
> > +static DEFINE_MUTEX(iosf_mbi_punit_mutex);
> > +static DEFINE_MUTEX(iosf_mbi_block_punit_i2c_access_count_mutex);
> > +static BLOCKING_NOTIFIER_HEAD(iosf_mbi_pmic_bus_access_notifier);
> > +static u32 iosf_mbi_block_punit_i2c_access_count;
> > +static u32 iosf_mbi_sem_address;
> > +static unsigned long iosf_mbi_sem_acquired;
> > +static struct pm_qos_request iosf_mbi_pm_qos;
> > +
> >   void iosf_mbi_punit_acquire(void)
> >   {
> >          mutex_lock(&iosf_mbi_punit_mutex);
> > @@ -204,6 +230,113 @@ void iosf_mbi_punit_release(void)
> >   }
> >   EXPORT_SYMBOL(iosf_mbi_punit_release);
> >
> > +static int iosf_mbi_get_sem(u32 *sem)
> > +{
> > +       int ret;
> > +
> > +       ret = iosf_mbi_read(BT_MBI_UNIT_PMC, MBI_REG_READ,
> > +                           iosf_mbi_sem_address, sem);
> > +       if (ret) {
> > +               dev_err(&mbi_pdev->dev, "Error punit semaphore read failed\n");
> > +               return ret;
> > +       }
> > +
> > +       *sem &= PUNIT_SEMAPHORE_BIT;
> > +       return 0;
> > +}
> > +
> > +static void iosf_mbi_reset_semaphore(void)
> > +{
> > +       if (iosf_mbi_modify(BT_MBI_UNIT_PMC, MBI_REG_READ,
> > +                           iosf_mbi_sem_address, 0, PUNIT_SEMAPHORE_BIT))
> > +               dev_err(&mbi_pdev->dev, "Error punit semaphore reset failed\n");
> > +
> > +       pm_qos_update_request(&iosf_mbi_pm_qos, PM_QOS_DEFAULT_VALUE);
> > +
> > +       blocking_notifier_call_chain(&iosf_mbi_pmic_bus_access_notifier,
> > +                                    MBI_PMIC_BUS_ACCESS_END, NULL);
> > +       mutex_unlock(&iosf_mbi_punit_mutex);
> > +}
> > +
> > +int iosf_mbi_block_punit_i2c_access(void)
> > +{
> > +       unsigned long start, end;
> > +       int ret = 0;
> > +       u32 sem;
> > +
> > +       if (WARN_ON(!mbi_pdev || !iosf_mbi_sem_address))
> > +               return -ENXIO;
> > +
> > +       mutex_lock(&iosf_mbi_block_punit_i2c_access_count_mutex);
> > +
> > +       if (iosf_mbi_block_punit_i2c_access_count > 0)
> > +               goto out;
> > +
> > +       mutex_lock(&iosf_mbi_punit_mutex);
> > +       blocking_notifier_call_chain(&iosf_mbi_pmic_bus_access_notifier,
> > +                                    MBI_PMIC_BUS_ACCESS_BEGIN, NULL);
> > +
> > +       /*
> > +        * Disallow the CPU to enter C6 or C7 state, entering these states
> > +        * requires the punit to talk to the pmic and if this happens while
> > +        * we're holding the semaphore, the SoC hangs.
> > +        */
> > +       pm_qos_update_request(&iosf_mbi_pm_qos, 0);
> > +
> > +       /* host driver writes to side band semaphore register */
> > +       ret = iosf_mbi_write(BT_MBI_UNIT_PMC, MBI_REG_WRITE,
> > +                            iosf_mbi_sem_address, PUNIT_SEMAPHORE_ACQUIRE);
> > +       if (ret) {
> > +               dev_err(&mbi_pdev->dev, "Error punit semaphore request failed\n");
> > +               goto out;
> > +       }
> > +
> > +       /* host driver waits for bit 0 to be set in semaphore register */
> > +       start = jiffies;
> > +       end = start + msecs_to_jiffies(SEMAPHORE_TIMEOUT);
> > +       do {
> > +               ret = iosf_mbi_get_sem(&sem);
> > +               if (!ret && sem) {
> > +                       iosf_mbi_sem_acquired = jiffies;
> > +                       dev_dbg(&mbi_pdev->dev, "punit semaphore acquired after %ums\n",
> > +                               jiffies_to_msecs(jiffies - start));
> > +                       goto out; /* Success, done. */
> > +               }
> > +
> > +               usleep_range(1000, 2000);
> > +       } while (time_before(jiffies, end));
> > +
> > +       ret = -ETIMEDOUT;
> > +       dev_err(&mbi_pdev->dev, "Error punit semaphore timed out, resetting\n");
> > +       iosf_mbi_reset_semaphore();
> > +
> > +       if (!iosf_mbi_get_sem(&sem))
> > +               dev_err(&mbi_pdev->dev, "PUNIT SEM: %d\n", sem);
> > +out:
> > +       if (!WARN_ON(ret))
> > +               iosf_mbi_block_punit_i2c_access_count++;
> > +
> > +       mutex_unlock(&iosf_mbi_block_punit_i2c_access_count_mutex);
> > +
> > +       return ret;
> > +}
> > +EXPORT_SYMBOL(iosf_mbi_block_punit_i2c_access);
> > +
> > +void iosf_mbi_unblock_punit_i2c_access(void)
> > +{
> > +       mutex_lock(&iosf_mbi_block_punit_i2c_access_count_mutex);
> > +
> > +       iosf_mbi_block_punit_i2c_access_count--;
> > +       if (iosf_mbi_block_punit_i2c_access_count == 0) {
> > +               iosf_mbi_reset_semaphore();
> > +               dev_dbg(&mbi_pdev->dev, "punit semaphore held for %ums\n",
> > +                       jiffies_to_msecs(jiffies - iosf_mbi_sem_acquired));
> > +       }
> > +
> > +       mutex_unlock(&iosf_mbi_block_punit_i2c_access_count_mutex);
> > +}
> > +EXPORT_SYMBOL(iosf_mbi_unblock_punit_i2c_access);
> > +
> >   int iosf_mbi_register_pmic_bus_access_notifier(struct notifier_block *nb)
> >   {
> >          int ret;
> > @@ -241,19 +374,14 @@ int iosf_mbi_unregister_pmic_bus_access_notifier(struct notifier_block *nb)
> >   }
> >   EXPORT_SYMBOL(iosf_mbi_unregister_pmic_bus_access_notifier);
> >
> > -int iosf_mbi_call_pmic_bus_access_notifier_chain(unsigned long val, void *v)
> > -{
> > -       return blocking_notifier_call_chain(
> > -                               &iosf_mbi_pmic_bus_access_notifier, val, v);
> > -}
> > -EXPORT_SYMBOL(iosf_mbi_call_pmic_bus_access_notifier_chain);
> > -
> >   void iosf_mbi_assert_punit_acquired(void)
> >   {
> >          WARN_ON(!mutex_is_locked(&iosf_mbi_punit_mutex));
> >   }
> >   EXPORT_SYMBOL(iosf_mbi_assert_punit_acquired);
> >
> > +/**************** iosf_mbi debug code ****************/
> > +
> >   #ifdef CONFIG_IOSF_MBI_DEBUG
> >   static u32     dbg_mdr;
> >   static u32     dbg_mcr;
> > @@ -338,7 +466,7 @@ static inline void iosf_debugfs_remove(void) { }
> >   #endif /* CONFIG_IOSF_MBI_DEBUG */
> >
> >   static int iosf_mbi_probe(struct pci_dev *pdev,
> > -                         const struct pci_device_id *unused)
> > +                         const struct pci_device_id *dev_id)
> >   {
> >          int ret;
> >
> > @@ -349,12 +477,16 @@ static int iosf_mbi_probe(struct pci_dev *pdev,
> >          }
> >
> >          mbi_pdev = pci_dev_get(pdev);
> > +       iosf_mbi_sem_address = dev_id->driver_data;
> > +
> >          return 0;
> >   }
> >
> >   static const struct pci_device_id iosf_mbi_pci_ids[] = {
> > -       { PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_BAYTRAIL) },
> > -       { PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_BRASWELL) },
> > +       { PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_BAYTRAIL),
> > +         .driver_data = PUNIT_SEMAPHORE_BYT },
> > +       { PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_BRASWELL),
> > +         .driver_data = PUNIT_SEMAPHORE_CHT },
> >          { PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_QUARK_X1000) },
> >          { PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_TANGIER) },
> >          { 0, },
> > @@ -371,6 +503,9 @@ static int __init iosf_mbi_init(void)
> >   {
> >          iosf_debugfs_init();
> >
> > +       pm_qos_add_request(&iosf_mbi_pm_qos, PM_QOS_CPU_DMA_LATENCY,
> > +                          PM_QOS_DEFAULT_VALUE);
> > +
> >          return pci_register_driver(&iosf_mbi_pci_driver);
> >   }
> >
> > @@ -381,6 +516,8 @@ static void __exit iosf_mbi_exit(void)
> >          pci_unregister_driver(&iosf_mbi_pci_driver);
> >          pci_dev_put(mbi_pdev);
> >          mbi_pdev = NULL;
> > +
> > +       pm_qos_remove_request(&iosf_mbi_pm_qos);
> >   }
> >
> >   module_init(iosf_mbi_init);
> > diff --git a/drivers/i2c/busses/i2c-designware-baytrail.c b/drivers/i2c/busses/i2c-designware-baytrail.c
> > index 9ca1feaba98f..8c84fa0b0384 100644
> > --- a/drivers/i2c/busses/i2c-designware-baytrail.c
> > +++ b/drivers/i2c/busses/i2c-designware-baytrail.c
> > @@ -3,139 +3,23 @@
> >    * Intel BayTrail PMIC I2C bus semaphore implementaion
> >    * Copyright (c) 2014, Intel Corporation.
> >    */
> > -#include <linux/delay.h>
> >   #include <linux/device.h>
> >   #include <linux/acpi.h>
> >   #include <linux/i2c.h>
> >   #include <linux/interrupt.h>
> > -#include <linux/pm_qos.h>
> >
> >   #include <asm/iosf_mbi.h>
> >
> >   #include "i2c-designware-core.h"
> >
> > -#define SEMAPHORE_TIMEOUT      500
> > -#define PUNIT_SEMAPHORE                0x7
> > -#define PUNIT_SEMAPHORE_CHT    0x10e
> > -#define PUNIT_SEMAPHORE_BIT    BIT(0)
> > -#define PUNIT_SEMAPHORE_ACQUIRE        BIT(1)
> > -
> > -static unsigned long acquired;
> > -
> > -static u32 get_sem_addr(struct dw_i2c_dev *dev)
> > -{
> > -       if (dev->flags & MODEL_CHERRYTRAIL)
> > -               return PUNIT_SEMAPHORE_CHT;
> > -       else
> > -               return PUNIT_SEMAPHORE;
> > -}
> > -
> > -static int get_sem(struct dw_i2c_dev *dev, u32 *sem)
> > -{
> > -       u32 addr = get_sem_addr(dev);
> > -       u32 data;
> > -       int ret;
> > -
> > -       ret = iosf_mbi_read(BT_MBI_UNIT_PMC, MBI_REG_READ, addr, &data);
> > -       if (ret) {
> > -               dev_err(dev->dev, "iosf failed to read punit semaphore\n");
> > -               return ret;
> > -       }
> > -
> > -       *sem = data & PUNIT_SEMAPHORE_BIT;
> > -
> > -       return 0;
> > -}
> > -
> > -static void reset_semaphore(struct dw_i2c_dev *dev)
> > -{
> > -       if (iosf_mbi_modify(BT_MBI_UNIT_PMC, MBI_REG_READ, get_sem_addr(dev),
> > -                           0, PUNIT_SEMAPHORE_BIT))
> > -               dev_err(dev->dev, "iosf failed to reset punit semaphore during write\n");
> > -
> > -       pm_qos_update_request(&dev->pm_qos, PM_QOS_DEFAULT_VALUE);
> > -
> > -       iosf_mbi_call_pmic_bus_access_notifier_chain(MBI_PMIC_BUS_ACCESS_END,
> > -                                                    NULL);
> > -       iosf_mbi_punit_release();
> > -}
> > -
> >   static int baytrail_i2c_acquire(struct dw_i2c_dev *dev)
> >   {
> > -       u32 addr;
> > -       u32 sem = PUNIT_SEMAPHORE_ACQUIRE;
> > -       int ret;
> > -       unsigned long start, end;
> > -
> > -       might_sleep();
> > -
> > -       if (!dev || !dev->dev)
> > -               return -ENODEV;
> > -
> > -       if (!dev->release_lock)
> > -               return 0;
> > -
> > -       iosf_mbi_punit_acquire();
> > -       iosf_mbi_call_pmic_bus_access_notifier_chain(MBI_PMIC_BUS_ACCESS_BEGIN,
> > -                                                    NULL);
> > -
> > -       /*
> > -        * Disallow the CPU to enter C6 or C7 state, entering these states
> > -        * requires the punit to talk to the pmic and if this happens while
> > -        * we're holding the semaphore, the SoC hangs.
> > -        */
> > -       pm_qos_update_request(&dev->pm_qos, 0);
> > -
> > -       addr = get_sem_addr(dev);
> > -
> > -       /* host driver writes to side band semaphore register */
> > -       ret = iosf_mbi_write(BT_MBI_UNIT_PMC, MBI_REG_WRITE, addr, sem);
> > -       if (ret) {
> > -               dev_err(dev->dev, "iosf punit semaphore request failed\n");
> > -               goto out;
> > -       }
> > -
> > -       /* host driver waits for bit 0 to be set in semaphore register */
> > -       start = jiffies;
> > -       end = start + msecs_to_jiffies(SEMAPHORE_TIMEOUT);
> > -       do {
> > -               ret = get_sem(dev, &sem);
> > -               if (!ret && sem) {
> > -                       acquired = jiffies;
> > -                       dev_dbg(dev->dev, "punit semaphore acquired after %ums\n",
> > -                               jiffies_to_msecs(jiffies - start));
> > -                       return 0;
> > -               }
> > -
> > -               usleep_range(1000, 2000);
> > -       } while (time_before(jiffies, end));
> > -
> > -       dev_err(dev->dev, "punit semaphore timed out, resetting\n");
> > -out:
> > -       reset_semaphore(dev);
> > -
> > -       ret = iosf_mbi_read(BT_MBI_UNIT_PMC, MBI_REG_READ, addr, &sem);
> > -       if (ret)
> > -               dev_err(dev->dev, "iosf failed to read punit semaphore\n");
> > -       else
> > -               dev_err(dev->dev, "PUNIT SEM: %d\n", sem);
> > -
> > -       WARN_ON(1);
> > -
> > -       return -ETIMEDOUT;
> > +       return iosf_mbi_block_punit_i2c_access();
> >   }
> >
> >   static void baytrail_i2c_release(struct dw_i2c_dev *dev)
> >   {
> > -       if (!dev || !dev->dev)
> > -               return;
> > -
> > -       if (!dev->acquire_lock)
> > -               return;
> > -
> > -       reset_semaphore(dev);
> > -       dev_dbg(dev->dev, "punit semaphore held for %ums\n",
> > -               jiffies_to_msecs(jiffies - acquired));
> > +       iosf_mbi_unblock_punit_i2c_access();
> >   }
> >
> >   int i2c_dw_probe_lock_support(struct dw_i2c_dev *dev)
> > @@ -166,14 +50,9 @@ int i2c_dw_probe_lock_support(struct dw_i2c_dev *dev)
> >          dev->release_lock = baytrail_i2c_release;
> >          dev->shared_with_punit = true;
> >
> > -       pm_qos_add_request(&dev->pm_qos, PM_QOS_CPU_DMA_LATENCY,
> > -                          PM_QOS_DEFAULT_VALUE);
> > -
> >          return 0;
> >   }
> >
> >   void i2c_dw_remove_lock_support(struct dw_i2c_dev *dev)
> >   {
> > -       if (dev->acquire_lock)
> > -               pm_qos_remove_request(&dev->pm_qos);
> >   }
> > --
> > 2.19.0.rc1