Re: [RFC PATCH v2 2/7] i2c: core: use I2C locking behaviour also for SMBUS

Simon Horman
2019-03-15T12:17:22Z

On Sat, Mar 02, 2019 at 02:47:30PM +0100, Wolfram Sang wrote:
> If I2C transfers are executed in atomic contexts, trylock is used
> instead of lock. This behaviour was missing for SMBUS, although a lot of
> transfers are of SMBUS type, either emulated or direct. So, factor out
> the locking routine into a helper and use it for I2C and SMBUS.
>
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
> Acked-by: Peter Rosin <peda@axentia.se>
> Acked-by: Tony Lindgren <tony@atomide.com>

Reviewed-by: Simon Horman <horms+renesas@verge.net.au>

> ---
> drivers/i2c/i2c-core-base.c | 11 +++--------
> drivers/i2c/i2c-core-smbus.c | 7 ++++++-
> drivers/i2c/i2c-core.h | 12 ++++++++++++
> 3 files changed, 21 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
> index cb6c5cb0df0b..004f8a3b6365 100644
> --- a/drivers/i2c/i2c-core-base.c
> +++ b/drivers/i2c/i2c-core-base.c
> @@ -1946,14 +1946,9 @@ int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
> * one (discarding status on the second message) or errno
> * (discarding status on the first one).
> */
> - if (in_atomic() || irqs_disabled()) {
> - ret = i2c_trylock_bus(adap, I2C_LOCK_SEGMENT);
> - if (!ret)
> - /* I2C activity is ongoing. */
> - return -EAGAIN;
> - } else {
> - i2c_lock_bus(adap, I2C_LOCK_SEGMENT);
> - }
> + ret = __i2c_lock_bus_helper(adap);
> + if (ret)
> + return ret;
>
> ret = __i2c_transfer(adap, msgs, num);
> i2c_unlock_bus(adap, I2C_LOCK_SEGMENT);
> diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c
> index 132119112596..357e083e8f45 100644
> --- a/drivers/i2c/i2c-core-smbus.c
> +++ b/drivers/i2c/i2c-core-smbus.c
> @@ -20,6 +20,8 @@
> #include <linux/i2c-smbus.h>
> #include <linux/slab.h>
>
> +#include "i2c-core.h"
> +
> #define CREATE_TRACE_POINTS
> #include <trace/events/smbus.h>
>
> @@ -530,7 +532,10 @@ s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
> {
> s32 res;
>
> - i2c_lock_bus(adapter, I2C_LOCK_SEGMENT);
> + res = __i2c_lock_bus_helper(adapter);
> + if (res)
> + return res;
> +
> res = __i2c_smbus_xfer(adapter, addr, flags, read_write,
> command, protocol, data);
> i2c_unlock_bus(adapter, I2C_LOCK_SEGMENT);
> diff --git a/drivers/i2c/i2c-core.h b/drivers/i2c/i2c-core.h
> index 37576f50fe20..6e98aa811980 100644
> --- a/drivers/i2c/i2c-core.h
> +++ b/drivers/i2c/i2c-core.h
> @@ -29,6 +29,18 @@ extern int __i2c_first_dynamic_bus_num;
>
> int i2c_check_7bit_addr_validity_strict(unsigned short addr);
>
> +static inline int __i2c_lock_bus_helper(struct i2c_adapter *adap)
> +{
> + int ret = 0;
> +
> + if (in_atomic() || irqs_disabled())
> + ret = i2c_trylock_bus(adap, I2C_LOCK_SEGMENT) ? 0 : -EAGAIN;
> + else
> + i2c_lock_bus(adap, I2C_LOCK_SEGMENT);
> +
> + return ret;
> +}
> +
> #ifdef CONFIG_ACPI
> const struct acpi_device_id *
> i2c_acpi_match_device(const struct acpi_device_id *matches,
> --
> 2.11.0
>
>
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