The device ignores any levels or transitions on the SCL pin when the device is idle, asleep or during waking up.
Linux kernel driver for atsha204a (atmel-sha204a.ko) also ignores return value from i2c wakeup send command, see: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/crypto/atmel-i2c.c?h=v5.19#n174 And also userspace Turris libatsha204 library ignores return value from wakeup send command, see: https://gitlab.nic.cz/turris/libatsha204/-/blob/v29.2/src/libatsha204/layer_ni2c.c#L75-76 U-Boot driver should do same thing. Fixes waking up ATSHA204 on Turris 1.x boards. Signed-off-by: Pali Rohár <p...@kernel.org> --- drivers/misc/atsha204a-i2c.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/drivers/misc/atsha204a-i2c.c b/drivers/misc/atsha204a-i2c.c index 81ecb5b6177b..fa2d5948f128 100644 --- a/drivers/misc/atsha204a-i2c.c +++ b/drivers/misc/atsha204a-i2c.c @@ -103,12 +103,13 @@ int atsha204a_wakeup(struct udevice *dev) for (try = 1; try <= 10; ++try) { debug("Try %i... ", try); + /* + * The device ignores any levels or transitions on the SCL pin + * when the device is idle, asleep or during waking up. + * Don't check for error when waking up the device. + */ memset(req, 0, 4); - res = atsha204a_send(dev, req, 4); - if (res) { - debug("failed on I2C send, trying again\n"); - continue; - } + atsha204a_send(dev, req, 4); udelay(ATSHA204A_TWLO_US + ATSHA204A_TWHI_US); -- 2.20.1
