From: Niklas Cassel <niklas.cassel@wdc.com>
Legacy software contains a standard mechanism for generating a reset to a
Serial ATA device - setting the SRST (software reset) bit in the Device
Control register.
Serial ATA has a more robust mechanism called COMRESET, also referred to
as port reset. A port reset is the preferred mechanism for error
recovery and should be used in place of software reset.
Commit e2a5d9b3d9c3 ("hw/ide/ahci: simplify and document PxCI handling")
improved the handling of PxCI, such that PxCI gets cleared after handling
a non-NCQ, or NCQ command (instead of incorrectly clearing PxCI after
receiving an arbitrary FIS).
However, simply clearing PxCI after a non-NCQ, or NCQ command, is not
enough, we also need to clear PxCI when receiving a SRST in the Device
Control register.
This fixes an issue for FreeBSD where the device would fail to reset.
The problem was not noticed in Linux, because Linux uses a COMRESET
instead of a legacy software reset by default.
Fixes: e2a5d9b3d9c3 ("hw/ide/ahci: simplify and document PxCI handling")
Reported-by: Marcin Juszkiewicz <marcin.juszkiewicz@linaro.org>
Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>