[PATCH -next 2/2] i2c: designware: Add support for new SoCs in AMDPSP driver

Mark Hasemeyer
2023-03-17T19:18:51Z

- /* Status field in command-response buffer is updated by PSP */
- status = READ_ONCE(req->hdr.status);
+ if (req) {
+ /* Status field in command-response buffer is updated by PSP */
+ status = READ_ONCE(req->hdr.status);
+ } else {
+ status = psp_smn_read(PSP_MBOX_CMD_OFFSET, &status);
+ status &= ~PSP_MBOX_FIELDS_READY;
+ }

The value of the mbox cmd register is getting clobbered by the return value
from psp_smn_read. This can cause bus arbitration to fail as the driver will
think it can grab the bus when it's actually in use by the PSP.