Den 2014-08-23 02:41, Mark Roszko skrev:
Prepare_recovery and unprepare_recovery are to configure the pad
multiplexer since thats platform specific. You don't care about the
adapter reference as you just need the scl_gpio and sda_gpio values to
know what pins to reconfigure.
In fact Atmel's pad mux functions look like this:
at91_set_A_periph(unsigned pin, int use_pullup)
at91_set_B_periph(unsigned pin, int use_pullup)
at91_set_C_periph(unsigned pin, int use_pullup)
.....
Here's the latest(or close) driver specific patch that slipped through
the cracks it seems?
http://www.spinics.net/lists/linux-i2c/msg11357.html
We are using a sama5d3-based machine which is almost entirely dt based,
so passing callbacks to the driver using the platform data seems like a
bad fit. Hard coding these calls in the driver won't really work either
(even for a single machine) since not all instances of the adapter exist
on the same peripheral. Ie, one adapter is on peripheral A and the
others are on peripheral B for this specific soc.
The way I assumed it would work was to declare a "recovery" pinmux state
in the device tree and then switch to that during the recovery and then
back to default once it's done. Could you expand a bit on this please?
Bus_recovery itself you have to call in the at91 driver on a
controller timeout just like the patch does.
if (ret == 0) {
dev_err(dev->dev, "controller timed out\n");
- at91_init_twi_bus(dev);
+ if (i2c_recover_bus(dev->adapter->bus_recovery_info) < 0)
+ at91_init_twi_bus(dev);
ret = -ETIMEDOUT;
goto error;
}
the call stack looks something like this
--at91_twi_xfer
----- i2c_recover_bus
--------- i2c_generic_gpio_recovery
-------------i2c_get_gpios_for_recovery (requests gpios)
-------------i2c_generic_recovery
----------------prepare_recovery (configure padmux to put gpio
on the pin)
----------------get_sda, get_scl (get gpio value, generic
function by default is fine for atmel)
----------------set_scl (set scl value, generic
function by default is fine for atmel)
----------------unrepare_recovery (configure padmux to put twi
back on the pin)
-------------i2c_put_gpios_for_recovery (frees gpios)
Somewhere in at91_twi_probe before the adapter is registered you also
have to setup the bus_recovery_info struct and set recover_bus to the
i2c_generic_gpio_recovery function similar to the patch linked.
That matches my previous understanding, thanks for the confirmation.
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