[PATCH] i2c: i2c-cadence: Don't register the adapter until it's ready

From: Mike Looijmans
Date: Thu Jan 05 2017 - 05:55:36 EST


The driver calls i2c_add_adapter before writing to config registers,
resulting in dmesg output like this, where devices fail to initialize:

cdns-i2c ff030000.i2c: timeout waiting on completion
pca953x 1-0041: failed reading register
pca953x: probe of 1-0041 failed with error -110
at24 1-0050: 512 byte 24c04 EEPROM, writable, 1 bytes/write
cdns-i2c ff030000.i2c: 100 kHz mmio ff030000 irq 197

The adapter is being used before it completed the "probe". To fix
this, make "i2c_add_adapter" the last thing it calls in probe.
It also makes sense to show the adapter initialization before
the devices on the bus.

Signed-off-by: Mike Looijmans <mike.looijmans@xxxxxxxx>
---
drivers/i2c/busses/i2c-cadence.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-cadence.c b/drivers/i2c/busses/i2c-cadence.c
index 6869712..7793bb8 100644
--- a/drivers/i2c/busses/i2c-cadence.c
+++ b/drivers/i2c/busses/i2c-cadence.c
@@ -962,10 +962,6 @@ static int cdns_i2c_probe(struct platform_device *pdev)
goto err_clk_dis;
}

- ret = i2c_add_adapter(&id->adap);
- if (ret < 0)
- goto err_clk_dis;
-
/*
* Cadence I2C controller has a bug wherein it generates
* invalid read transaction after HW timeout in master receiver mode.
@@ -978,6 +974,10 @@ static int cdns_i2c_probe(struct platform_device *pdev)
dev_info(&pdev->dev, "%u kHz mmio %08lx irq %d\n",
id->i2c_clk / 1000, (unsigned long)r_mem->start, id->irq);

+ ret = i2c_add_adapter(&id->adap);
+ if (ret < 0)
+ goto err_clk_dis;
+
return 0;

err_clk_dis:
--
1.9.1