> From: Guilherme G. Piccoli [mailto:gpicc...@linux.vnet.ibm.com]
> Sent: Tuesday, September 19, 2017 9:12 AM
> To: dl-esc-Aacraid Linux Driver <aacr...@microsemi.com>; linux-
> s...@vger.kernel.org
> Cc: gpicc...@linux.vnet.ibm.com; Raghava Aditya Renukunta
> <raghavaaditya.renuku...@microsemi.com>; Dave Carroll
> <david.carr...@microsemi.com>; brk...@linux.vnet.ibm.com;
> dougm...@linux.vnet.ibm.com; sta...@vger.kernel.org
> Subject: [PATCH] scsi: aacraid: Add a small delay after IOP reset
>
> Commit 0e9973ed3382 ("scsi: aacraid: Add periodic checks to see IOP reset
> status") changed the way driver checks if a reset succeeded. Now, after an IOP
> reset, aacraid immediately start polling a register to verify the reset is
> complete.
>
> This behavior cause regressions on the reset path in PowerPC (at least).
> Since the delay after the IOP reset was removed by the aforementioned patch,
> the fact driver just starts to read a register instantly after the reset was
> issued
> (by writing in another register) "corrupts" the reset procedure, which ends up
> failing all the time.
>
> The issue highly impacted kdump on PowerPC, since on kdump path we
> proactively issue a reset in adapter (through the reset_devices kernel
> parameter).
>
> This patch (re-)adds a delay right after IOP reset is issued. Empirically we
> measured that 3 seconds is enough, but for safety reasons we delay for 5s (and
> since it was 30s before, 5s is still a small amount).
>
> For reference, without this patch we observe the following messages on kdump
> kernel boot process:
>
> [ 76.294] aacraid 0003:01:00.0: IOP reset failed
> [ 76.294] aacraid 0003:01:00.0: ARC Reset attempt failed
> [ 86.524] aacraid 0003:01:00.0: adapter kernel panic'd ff.
> [ 86.524] aacraid 0003:01:00.0: Controller reset type is 3
> [ 86.524] aacraid 0003:01:00.0: Issuing IOP reset
> [146.534] aacraid 0003:01:00.0: IOP reset failed
> [146.534] aacraid 0003:01:00.0: ARC Reset attempt failed
>
> Fixes: 0e9973ed3382 ("scsi: aacraid: Add periodic checks to see IOP reset
> status")
> Cc: sta...@vger.kernel.org # v4.13+
> Signed-off-by: Guilherme G. Piccoli <gpicc...@linux.vnet.ibm.com>
> ---
Acked-by: Dave Carroll <david.carr...@microsemi.com>
