Hi Wolfram,

On 04/24/2016 11:10 PM, Wolfram Sang wrote:
+/*
+ * i2c bus recovery routines
+ * get_scl and set_scl must be defined to avoid the recover_bus field of
+ * i2c_bus_recovery_info to be overriden with NULL during the
+ * i2c_add_adapter call
+ */
Oh, that shouldn't be like this. Can you try this patch and remove the
empty functions please?

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 4979728f7fb2de..604936955807e5 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -1595,10 +1595,12 @@ static int i2c_register_adapter(struct i2c_adapter 
*adap)
bri->get_scl = get_scl_gpio_value;
                        bri->set_scl = set_scl_gpio_value;
-               } else if (!bri->set_scl || !bri->get_scl) {
+               } else if (bri->recover_bus == i2c_generic_scl_recovery) {
                        /* Generic SCL recovery */
-                       dev_err(&adap->dev, "No {get|set}_gpio() found, not using 
recovery\n");
-                       adap->bus_recovery_info = NULL;
+                       if (!bri->set_scl || !bri->get_scl) {
+                               dev_err(&adap->dev, "No {get|set}_scl() found, not 
using recovery\n");
+                               adap->bus_recovery_info = NULL;
+                       }
                }
        }
+static int st_i2c_recover_bus(struct i2c_adapter *i2c_adap)
+{
Can you describe what the function does? It is not clear to me that it
generates 9 scl pulses.
I agree, it would need some comments.
This IP is dual-role, it can do either SPI or I2C.
The trick is to switch to SPI mode, 9 bits words and write a 0,
so that 9 clock pulses are generated.

This is easier to manage than switching to GPIO mode,
as we don't need to provide the gpio handles in DT, and no need to put/get the pinctrl handle.

Regards,
Maxime

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