soc/amd/common/block/espi_util: Work around in-band reset race condition

When performing an in-band reset the host controller and the
peripheral can have mismatched IO configs.

i.e., The eSPI peripheral can be in IO-4 mode while, the
eSPI host will be in IO-1. This results in the peripheral
getting invalid packets and thus not responding. This causes the
NO_RESPONSE status bit to be set and cause eSPI init to fail.

If the peripheral is alerting when we perform an in-band
reset, there is a race condition in espi_send_command.
1) espi_send_command clears the interrupt status.
2) eSPI host controller hardware notices the alert and sends
   a GET_STATUS.
3) espi_send_command writes the in-band reset command.
4) eSPI hardware enqueues the in-band reset until GET_STATUS
   is complete.
5) GET_STATUS fails with NO_RESPONSE and sets the interrupt
   status.
6) eSPI hardware performs in-band reset.
7) espi_send_command checks the status and sees a
   NO_RESPONSE bit.

As a workaround we allow the NO_RESPONSE status code when
we perform an in-band reset.

BUG=b:186135022
TEST=suspend_stress_test and S5->S0 tests on guybrush and zork.

Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Change-Id: I71271377f20eaf29032214be98794e1645d9b70a
Reviewed-on: https://review.coreboot.org/c/coreboot/+/54070
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>
Reviewed-by: Rob Barnes <robbarnes@google.com>

0 files changed, 0 insertions, 0 deletions