On 2019-11-14 06:04, Bean Huo (beanhuo) wrote:
In UFS host reset and restore path, before probe, we stop and start
the host
controller once. After host controller is stopped, the pending
requests, if any,
are cleared from the doorbell, but no completion IRQ would be raised
due to the
hba is stopped.
These pending requests shall be completed along with the first NOP_OUT
command(as it is the first command which can raise a transfer
completion
IRQ) sent during probe.
Hi, Can
I am not sure for this point, because there is HW/SW device reset
before or after host reset/restore.
Device HW/SW reset also will clear the pended tasks in device side.
That will be better.
I think Qcom platform already enabled HW reset.
//Bean
Hi Bean,
By pending tasks here, it means the requests sent down from scsi/block
layer,
but have not yet been handled by ufs driver(cmd->scsi_done() have not
been called yet for these requests).
For these requests, although removed by host and UFS device in their HW
queues(doorbell),
UFS driver still needs to complete them from SW side(call
cmd->scsi_done() for each one of them) to
let upper layer know that they are finished(although not successfully)
to avoid hitting
timeout of these pending tasks. I hope I make my explanation clearly.
Best Regards,
Can Guo.
Since the OCSs of these pending requests are not SUCCESS(because they
are not
yet literally finished), their UPIUs shall be dumped. When there are
multiple
pending requests, the UPIU dump can be overwhelming and may lead to
stability
issues because it is in atomic context.
Therefore, before probe, complete these pending requests right after
host
controller is stopped.
