On Wed, Feb 23, 2022 at 02:48:38PM +0100, Hans de Goede wrote:
> Lock the adapter while setting the suspended flag, to ensure that other
> locked code always sees the change immediately, rather then possibly using
> a stale value.
>
> This involves splitting the suspend/resume callbacks into separate runtime
> and normal suspend/resume calls. This is necessary because i2c_dw_xfer()
> will get called by the i2c-core with the adapter locked and it in turn
> calls the runtime-resume callback through pm_runtime_get_sync().
>
> So the runtime versions of the suspend/resume callbacks cannot take
> the adapter-lock. Note this patch simply makes the runtime suspend/resume
> callbacks not deal with the suspended flag at all. During runtime the
> pm_runtime_get_sync() from i2c_dw_xfer() will always ensure that the
> adapter is resumed when necessary.
>
> The suspended flag check is only necessary to check proper suspend/resume
> ordering during normal suspend/resume which makes the pm_runtime_get_sync()
> call a no-op.
Both patches look good to me and seems like a nice clean up. Not sure if the
first one should be backported (and hence have a Fixes tag).
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> ---
> drivers/i2c/busses/i2c-designware-pcidrv.c | 31 +++++++++++++++++----
> drivers/i2c/busses/i2c-designware-platdrv.c | 31 +++++++++++++++++----
> 2 files changed, 52 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-designware-pcidrv.c b/drivers/i2c/busses/i2c-designware-pcidrv.c
> index ef4250f8852b..9553d7075223 100644
> --- a/drivers/i2c/busses/i2c-designware-pcidrv.c
> +++ b/drivers/i2c/busses/i2c-designware-pcidrv.c
> @@ -213,14 +213,30 @@ static struct dw_pci_controller dw_pci_controllers[] = {
> },
> };
>
> +static int __maybe_unused i2c_dw_pci_runtime_suspend(struct device *dev)
> +{
> + struct dw_i2c_dev *i_dev = dev_get_drvdata(dev);
> +
> + i_dev->disable(i_dev);
> + return 0;
> +}
> +
> static int __maybe_unused i2c_dw_pci_suspend(struct device *dev)
> {
> struct dw_i2c_dev *i_dev = dev_get_drvdata(dev);
>
> + i2c_lock_bus(&i_dev->adapter, I2C_LOCK_ROOT_ADAPTER);
> i_dev->suspended = true;
> - i_dev->disable(i_dev);
> + i2c_unlock_bus(&i_dev->adapter, I2C_LOCK_ROOT_ADAPTER);
>
> - return 0;
> + return i2c_dw_pci_runtime_suspend(dev);
> +}
> +
> +static int __maybe_unused i2c_dw_pci_runtime_resume(struct device *dev)
> +{
> + struct dw_i2c_dev *i_dev = dev_get_drvdata(dev);
> +
> + return i_dev->init(i_dev);
> }
>
> static int __maybe_unused i2c_dw_pci_resume(struct device *dev)
> @@ -228,14 +244,19 @@ static int __maybe_unused i2c_dw_pci_resume(struct device *dev)
> struct dw_i2c_dev *i_dev = dev_get_drvdata(dev);
> int ret;
>
> - ret = i_dev->init(i_dev);
> + ret = i2c_dw_pci_runtime_resume(dev);
> +
> + i2c_lock_bus(&i_dev->adapter, I2C_LOCK_ROOT_ADAPTER);
> i_dev->suspended = false;
> + i2c_unlock_bus(&i_dev->adapter, I2C_LOCK_ROOT_ADAPTER);
>
> return ret;
> }
>
> -static UNIVERSAL_DEV_PM_OPS(i2c_dw_pm_ops, i2c_dw_pci_suspend,
> - i2c_dw_pci_resume, NULL);
> +static const struct dev_pm_ops i2c_dw_pm_ops = {
> + SET_SYSTEM_SLEEP_PM_OPS(i2c_dw_pci_suspend, i2c_dw_pci_resume)
> + SET_RUNTIME_PM_OPS(i2c_dw_pci_runtime_suspend, i2c_dw_pci_runtime_resume, NULL)
> +};
>
> static int i2c_dw_pci_probe(struct pci_dev *pdev,
> const struct pci_device_id *id)
> diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
> index 2bd81abc86f6..8e45f65bab73 100644
> --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> @@ -368,12 +368,10 @@ static void dw_i2c_plat_complete(struct device *dev)
> #endif
>
> #ifdef CONFIG_PM
> -static int dw_i2c_plat_suspend(struct device *dev)
> +static int dw_i2c_plat_runtime_suspend(struct device *dev)
> {
> struct dw_i2c_dev *i_dev = dev_get_drvdata(dev);
>
> - i_dev->suspended = true;
> -
> if (i_dev->shared_with_punit)
> return 0;
>
> @@ -383,7 +381,18 @@ static int dw_i2c_plat_suspend(struct device *dev)
> return 0;
> }
>
> -static int dw_i2c_plat_resume(struct device *dev)
> +static int dw_i2c_plat_suspend(struct device *dev)
> +{
> + struct dw_i2c_dev *i_dev = dev_get_drvdata(dev);
> +
> + i2c_lock_bus(&i_dev->adapter, I2C_LOCK_ROOT_ADAPTER);
> + i_dev->suspended = true;
> + i2c_unlock_bus(&i_dev->adapter, I2C_LOCK_ROOT_ADAPTER);
> +
> + return dw_i2c_plat_runtime_suspend(dev);
> +}
> +
> +static int dw_i2c_plat_runtime_resume(struct device *dev)
> {
> struct dw_i2c_dev *i_dev = dev_get_drvdata(dev);
>
> @@ -391,7 +400,19 @@ static int dw_i2c_plat_resume(struct device *dev)
> i2c_dw_prepare_clk(i_dev, true);
>
> i_dev->init(i_dev);
> +
> + return 0;
> +}
> +
> +static int dw_i2c_plat_resume(struct device *dev)
> +{
> + struct dw_i2c_dev *i_dev = dev_get_drvdata(dev);
> +
> + dw_i2c_plat_runtime_resume(dev);
> +
> + i2c_lock_bus(&i_dev->adapter, I2C_LOCK_ROOT_ADAPTER);
> i_dev->suspended = false;
> + i2c_unlock_bus(&i_dev->adapter, I2C_LOCK_ROOT_ADAPTER);
>
> return 0;
> }
> @@ -400,7 +421,7 @@ static const struct dev_pm_ops dw_i2c_dev_pm_ops = {
> .prepare = dw_i2c_plat_prepare,
> .complete = dw_i2c_plat_complete,
> SET_LATE_SYSTEM_SLEEP_PM_OPS(dw_i2c_plat_suspend, dw_i2c_plat_resume)
> - SET_RUNTIME_PM_OPS(dw_i2c_plat_suspend, dw_i2c_plat_resume, NULL)
> + SET_RUNTIME_PM_OPS(dw_i2c_plat_runtime_suspend, dw_i2c_plat_runtime_resume, NULL)
> };
>
> #define DW_I2C_DEV_PMOPS (&dw_i2c_dev_pm_ops)
> --
> 2.35.1
>
--
With Best Regards,
Andy Shevchenko
