On Sun, 2017-01-01 at 21:15 +0100, Hans de Goede wrote:
> Use iosf_mbi_modify instead of iosf_mbi_read + iosf_mbi_write so that
> we keep the iosf_mbi_lock locked during the read-modify-write done to
> reset the semaphore.
>
While patch itself looks good to me, I think it reduces a probability to
race and doesn't eliminate an issue completely. Can you check i915 code
how it's done there?
> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> ---
> Changes in v5:
> -New patch in v5 of this patch-set
> ---
> drivers/i2c/busses/i2c-designware-baytrail.c | 11 ++---------
> 1 file changed, 2 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-designware-baytrail.c
> b/drivers/i2c/busses/i2c-designware-baytrail.c
> index 650a700..8df529c 100644
> --- a/drivers/i2c/busses/i2c-designware-baytrail.c
> +++ b/drivers/i2c/busses/i2c-designware-baytrail.c
> @@ -47,15 +47,8 @@ static int get_sem(struct dw_i2c_dev *dev, u32
> *sem)
>
> static void reset_semaphore(struct dw_i2c_dev *dev)
> {
> - u32 data;
> -
> - if (iosf_mbi_read(BT_MBI_UNIT_PMC, MBI_REG_READ,
> PUNIT_SEMAPHORE, &data)) {
> - dev_err(dev->dev, "iosf failed to reset punit
> semaphore during read\n");
> - return;
> - }
> -
> - data &= ~PUNIT_SEMAPHORE_BIT;
> - if (iosf_mbi_write(BT_MBI_UNIT_PMC, MBI_REG_WRITE,
> PUNIT_SEMAPHORE, data))
> + if (iosf_mbi_modify(BT_MBI_UNIT_PMC, MBI_REG_READ,
> PUNIT_SEMAPHORE,
> + 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);
--
Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Intel Finland Oy
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