From: Peter Rosin <peda@axentia.se>
To: Wolfram Sang <wsa+renesas@sang-engineering.com>,
linux-i2c@vger.kernel.org
Cc: linux-renesas-soc@vger.kernel.org,
Stefan Lengfeld <contact@stefanchrist.eu>,
preid@electromag.com.au, linux-omap@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, Keerthy <j-keerthy@ti.com>,
Tero Kristo <t-kristo@ti.com>,
Grygorii Strashko <grygorii.strashko@ti.com>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Subject: Re: [RFC PATCH 3/4] i2c: core: use I2C locking behaviour also for SMBUS
Date: Thu, 20 Sep 2018 19:31:19 +0200 [thread overview]
Message-ID: <e31d69ed-d849-db98-00c2-27d489a2dac1@axentia.se> (raw)
In-Reply-To: <20180920161423.13990-4-wsa+renesas@sang-engineering.com>
On 2018-09-20 18:14, 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>
Is it ok with static analyzers to "hide" the locking in helpers like
this? Will it not be harder for them to "see" what's going on? But I
don't think we have any annotations anyway, so...
Acked-by: Peter Rosin <peda@axentia.se>
> ---
> 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 799776c6d421..904b4d2ebefa 100644
> --- a/drivers/i2c/i2c-core-base.c
> +++ b/drivers/i2c/i2c-core-base.c
> @@ -1943,14 +1943,9 @@ 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 9cd66cabb84f..dbb46edb8e02 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,
>
next prev parent reply other threads:[~2018-09-20 23:16 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-20 16:14 [RFC PATCH 0/4] i2c: core: introduce master_xfer_irqless Wolfram Sang
2018-09-20 16:14 ` [RFC PATCH 1/4] i2c: core: remove outdated DEBUG output Wolfram Sang
2018-09-20 17:23 ` Peter Rosin
2018-10-05 16:14 ` Wolfram Sang
2018-09-20 16:14 ` [RFC PATCH 2/4] i2c: core: remove level of indentation in i2c_transfer Wolfram Sang
2018-09-20 17:26 ` Peter Rosin
2018-09-20 22:46 ` Wolfram Sang
2018-10-05 16:15 ` Wolfram Sang
2018-09-20 16:14 ` [RFC PATCH 3/4] i2c: core: use I2C locking behaviour also for SMBUS Wolfram Sang
2018-09-20 17:31 ` Peter Rosin [this message]
2018-09-20 22:48 ` Wolfram Sang
2018-09-20 16:14 ` [RFC PATCH 4/4] i2c: core: introduce master_xfer_irqless callback Wolfram Sang
2018-09-20 17:41 ` Peter Rosin
2018-09-20 22:55 ` Wolfram Sang
2018-10-18 10:44 ` Russell King - ARM Linux
2019-02-09 18:03 ` Wolfram Sang
2018-09-20 22:02 ` [RFC PATCH 0/4] i2c: core: introduce master_xfer_irqless Tony Lindgren
2018-09-20 22:56 ` Wolfram Sang
2018-10-18 10:35 ` Keerthy
2018-09-20 23:01 ` Wolfram Sang
2018-09-23 20:20 ` Stefan Lengfeld
2018-10-07 15:39 ` [RFC PATCH 0/3] " Stefan Lengfeld
2018-10-07 15:39 ` [RFC PATCH 1/3] i2c: imx: implement master_xfer_irqless callback Stefan Lengfeld
2018-10-08 10:06 ` Andy Shevchenko
2018-10-07 15:39 ` [RFC PATCH 2/3] watchdog: da9062: avoid regmap in restart handler Stefan Lengfeld
2018-10-08 10:07 ` Andy Shevchenko
2018-10-07 15:39 ` [RFC PATCH 3/3] ARM: dts: phyboard-mira-dl: rely on PMIC for reboot and watchdog Stefan Lengfeld
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