Hi Zhang Ying,
On 11/12/2018 08:34 AM, Zhang Ying-22455 wrote:
> From: Joshua Frkuska <joshua_frkuska@xxxxxxxxxx>
>
> This patch adds hardware supported slave-mode with master arbitration
> via the i2c generic slave interface. This allows master transactions
> to be supported while a slave-mode device is in idle.
>
> To enable this functionality enable i2c slave support.
>
> CONFIG_I2C_SLAVE=y
>
> If i2c-slave support is not enabled in the kernel config, we support
> master-mode only and the slave-mode support is not compiled in.
>
> A queue backed event-driven state machine is implemented in order to
> handle events in the order they occur in the hardware. The states
> for the most part follow the logic charts in the imx reference manual
>
> Signed-off-by: Maxim Syrchin <msyrchin@xxxxxxxxxxxxx>
> [joshua_frkuska@xxxxxxxxxx: Reworked patchset for upstream submission]
> Signed-off-by: Joshua Frkuska <joshua_frkuska@xxxxxxxxxx>
> Signed-off-by: Zhang Ying-22455 <ying.zhang22455@xxxxxxx>
[snip]
> +static int i2c_imx_reg_slave(struct i2c_client *slave)
> +{
> + struct imx_i2c_struct *i2c_imx = i2c_get_adapdata(slave->adapter);
> + int result;
> + struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
> +
> + dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
> +
> + if (i2c_imx->slave)
> + return -EBUSY;
> +
> + if (slave->flags & I2C_CLIENT_TEN)
> + return -EAFNOSUPPORT;
> +
> + i2c_imx->slave = slave;
> +
> + /* Set the Slave address */
> + imx_i2c_write_reg((i2c_imx->slave->addr << 1), i2c_imx, IMX_I2C_IADR);
> + result = i2c_imx_hw_start(i2c_imx);
> + if (result)
> + return result;
> +
> + i2c_imx->slave_task = kthread_run(i2c_imx_slave_threadfn,
> + i2c_imx, "i2c-slave-%s",
> + i2c_imx->adapter.name);
> +
> + if (IS_ERR(i2c_imx->slave_task))
> + return PTR_ERR(i2c_imx->slave_task);
> +
> + sched_setscheduler(i2c_imx->slave_task, SCHED_FIFO, ¶m);
kernel thread priority setting done by a kernel driver is NAKed, because it
affects the whole running system and thus it shall (as implied by "it can")
be done on a higher level, for instance from userspace.
Decisively remove sched_setscheduler() call from the change.
> +
> + i2c_imx_slave_init(i2c_imx);
> +
> + return 0;
> +}
> +
--
Best wishes,
Vladimir
