Previous patch for this driver breaks i2c initialization.
commit 8bcf12ccce89 ("i2c: mvtwsi.c: Avoid NULL dereference")
If actual_speed is passed as NULL in this function: static void __twsi_i2c_init(struct mvtwsi_registers *twsi, int speed, int slaveadd, uint *actual_speed) than __twsi_i2c_set_bus_speed never get called. This causes i2c clock to run on default speed - 2MHz (measured with oscilloscope). This is issue on some boards, sunxi for example, since on I2C0 bus PMU is connected.
The bootlogs with and without the patch are as follows:
Wihtout the patch: U-Boot SPL 2018.03-rc2 (Feb 13 2018 - 09:23:17 +0200) DRAM: 1024 MiB Failed to set core voltage! Can't set CPU frequency Trying to boot from FEL
U-Boot 2018.03-rc2 (Feb 13 2018 - 09:23:17 +0200) Allwinner Technology
CPU: Allwinner A20 (SUN7I) Model: Olimex A20-OLinuXino-LIME2 I2C: ready DRAM: 1 GiB MMC: SUNXI SD/MMC: 0
With the patch: U-Boot SPL 2018.03-rc2-00001-g838ff85 (Feb 13 2018 - 09:24:34 +0200) DRAM: 1024 MiB CPU: 912000000Hz, AXI/AHB/APB: 3/2/2 Trying to boot from FEL
U-Boot 2018.03-rc2-00001-g838ff85 (Feb 13 2018 - 09:24:34 +0200) Allwinner Technology
CPU: Allwinner A20 (SUN7I) Model: Olimex A20-OLinuXino-LIME2 I2C: ready DRAM: 1 GiB MMC: SUNXI SD/MMC: 0
Signed-off-by: Stefan Mavrodiev stefan@olimex.com --- drivers/i2c/mvtwsi.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/i2c/mvtwsi.c b/drivers/i2c/mvtwsi.c index 30bee0d..38bca89 100644 --- a/drivers/i2c/mvtwsi.c +++ b/drivers/i2c/mvtwsi.c @@ -487,11 +487,14 @@ static uint __twsi_i2c_set_bus_speed(struct mvtwsi_registers *twsi, static void __twsi_i2c_init(struct mvtwsi_registers *twsi, int speed, int slaveadd, uint *actual_speed) { + uint tmp_speed; + /* Reset controller */ twsi_reset(twsi); /* Set speed */ + tmp_speed = __twsi_i2c_set_bus_speed(twsi, speed); if (actual_speed) - *actual_speed = __twsi_i2c_set_bus_speed(twsi, speed); + *actual_speed = tmp_speed; /* Set slave address; even though we don't use it */ writel(slaveadd, &twsi->slave_address); writel(0, &twsi->xtnd_slave_addr);