usb: typec: ucsi_ccg: Add retry mechanism in ccg_read

CCG4 firmware occasionally fails to respond to I2C read requests,
especially when reading cci and intr_reg from the ISR path. In these
cases, i2c_transfer() returns -EREMOTEIO.

The CCG4 is EOL, and Infineon no longer supports firmware updates, so
a software workaround is necessary.

Attempt the read up to CCG_READ_MAX_RETRIES (4) times in total when
-EREMOTEIO is returned, sleeping ~1 ms via fsleep() between attempts.
This allows recovery from transient I2C failures without affecting
other error paths.

The sleep is safe because ccg_read() is called both from process
context and from ccg_irq_handler(), which runs in threaded IRQ
context (registered via request_threaded_irq() with a NULL hard-IRQ
handler), so sleeping is allowed in both cases.

Fixes: 247c554a14aa ("usb: typec: ucsi: add support for Cypress CCGx")
Cc: stable <stable@kernel.org>
Signed-off-by: Wayne Chang <waynec@nvidia.com>
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://patch.msgid.link/20260916061858.1471606-1-waynec@nvidia.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

0 files changed, 0 insertions, 0 deletions