| Message ID | 20200824225254.1114-1-mark.tomlinson@alliedtelesis.co.nz |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v2] i2c: mv64xxx: Add bus error recovery | expand |
On Tue, Aug 25, 2020 at 10:52:54AM +1200, Mark Tomlinson wrote: > This adds i2c bus recovery to the mv64xxx driver. > > Implement bus recovery to recover from SCL/SDA stuck low. > > This uses the generic recovery function, setting the clock/data lines as > GPIO pins, and sending 9 clocks to try and recover the bus. > > Signed-off-by: Mark Tomlinson <mark.tomlinson@alliedtelesis.co.nz> > --- > Changes in v2: > - use generic GPIO recovery function. Thank you for doing that! Glad to see the new helper function works for you as well. The initialization code is all well, but I wonder about the use of i2c_recover_bus(). Recovery should be tried only if it is detected that SDA is pulled low when the bus should be free. So, you shouldn't call i2c_recover_bus() in unconditionally in probe(). Can your HW detect if SDA is stuck low?
On Tue, 2020-08-25 at 11:26 +0200, Wolfram Sang wrote: > On Tue, Aug 25, 2020 at 10:52:54AM +1200, Mark Tomlinson wrote: > > This adds i2c bus recovery to the mv64xxx driver. > > Implement bus recovery to recover from SCL/SDA stuck low. > > This uses the generic recovery function, setting the clock/data lines as > GPIO pins, and sending 9 clocks to try and recover the bus. > > Signed-off-by: Mark Tomlinson <mark.tomlinson@alliedtelesis.co.nz> > --- > Changes in v2: > - use generic GPIO recovery function. > > Thank you for doing that! Glad to see the new helper function works for > you as well. The initialization code is all well, but I wonder about the > use of i2c_recover_bus(). Recovery should be tried only if it is > detected that SDA is pulled low when the bus should be free. So, you > shouldn't call i2c_recover_bus() in unconditionally in probe(). Can your > HW detect if SDA is stuck low? We actually don't need this call, as the bootloader checks and leaves the bus in a good state. I will remove this from the patch.
diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c index 8d9d4ffdcd24..e0f0c76c0d3b 100644 --- a/drivers/i2c/busses/i2c-mv64xxx.c +++ b/drivers/i2c/busses/i2c-mv64xxx.c @@ -17,6 +17,7 @@ #include <linux/interrupt.h> #include <linux/mv643xx_i2c.h> #include <linux/platform_device.h> +#include <linux/pinctrl/consumer.h> #include <linux/reset.h> #include <linux/io.h> #include <linux/of.h> @@ -147,6 +148,7 @@ struct mv64xxx_i2c_data { bool irq_clear_inverted; /* Clk div is 2 to the power n, not 2 to the power n + 1 */ bool clk_n_base_0; + struct i2c_bus_recovery_info rinfo; }; static struct mv64xxx_i2c_regs mv64xxx_i2c_regs_mv64xxx = { @@ -325,7 +327,8 @@ mv64xxx_i2c_fsm(struct mv64xxx_i2c_data *drv_data, u32 status) drv_data->msg->flags); drv_data->action = MV64XXX_I2C_ACTION_SEND_STOP; mv64xxx_i2c_hw_init(drv_data); - drv_data->rc = -EIO; + i2c_recover_bus(&drv_data->adapter); + drv_data->rc = -EAGAIN; } } @@ -562,6 +565,7 @@ mv64xxx_i2c_wait_for_completion(struct mv64xxx_i2c_data *drv_data) "time_left: %d\n", drv_data->block, (int)time_left); mv64xxx_i2c_hw_init(drv_data); + i2c_recover_bus(&drv_data->adapter); } } else spin_unlock_irqrestore(&drv_data->lock, flags); @@ -871,6 +875,22 @@ mv64xxx_of_config(struct mv64xxx_i2c_data *drv_data, } #endif /* CONFIG_OF */ +static int mv64xxx_i2c_init_recovery_info(struct mv64xxx_i2c_data *drv_data, + struct device *dev) +{ + struct i2c_bus_recovery_info *rinfo = &drv_data->rinfo; + + rinfo->pinctrl = devm_pinctrl_get(dev); + if (IS_ERR(rinfo->pinctrl)) { + if (PTR_ERR(rinfo->pinctrl) == -EPROBE_DEFER) + return -EPROBE_DEFER; + dev_err(dev, "can't get pinctrl, bus recovery not supported\n"); + return PTR_ERR(rinfo->pinctrl); + } + drv_data->adapter.bus_recovery_info = rinfo; + return 0; +} + static int mv64xxx_i2c_probe(struct platform_device *pd) { @@ -927,6 +947,10 @@ mv64xxx_i2c_probe(struct platform_device *pd) goto exit_reset; } + rc = mv64xxx_i2c_init_recovery_info(drv_data, &pd->dev); + if (rc == -EPROBE_DEFER) + goto exit_reset; + drv_data->adapter.dev.parent = &pd->dev; drv_data->adapter.algo = &mv64xxx_i2c_algo; drv_data->adapter.owner = THIS_MODULE; @@ -950,6 +974,7 @@ mv64xxx_i2c_probe(struct platform_device *pd) "mv64xxx: Can't add i2c adapter, rc: %d\n", -rc); goto exit_free_irq; } + i2c_recover_bus(&drv_data->adapter); return 0;
This adds i2c bus recovery to the mv64xxx driver. Implement bus recovery to recover from SCL/SDA stuck low. This uses the generic recovery function, setting the clock/data lines as GPIO pins, and sending 9 clocks to try and recover the bus. Signed-off-by: Mark Tomlinson <mark.tomlinson@alliedtelesis.co.nz> --- Changes in v2: - use generic GPIO recovery function. drivers/i2c/busses/i2c-mv64xxx.c | 27 ++++++++++++++++++++++++++- 1 file changed, 26 insertions(+), 1 deletion(-)