ata: libata-eh: do not thaw the port twice in ata_eh_reset()
authorNiklas Cassel <niklas.cassel@wdc.com>
Wed, 13 Sep 2023 22:19:17 +0000 (00:19 +0200)
committerDamien Le Moal <dlemoal@kernel.org>
Sat, 16 Sep 2023 12:11:28 +0000 (21:11 +0900)
commit7a3bc2b3989e05bbaa904a63279049a401491c84
tree1b0770f5503a390d28c5c000fe0100cd4f208ca2
parent80cc944eca4f0baa9c381d0706f3160e491437f2
ata: libata-eh: do not thaw the port twice in ata_eh_reset()

commit 1e641060c4b5 ("libata: clear eh_info on reset completion") added
a workaround that broke the retry mechanism in ATA EH.

Tejun himself suggested to remove this workaround when it was identified
to cause additional problems:
https://lore.kernel.org/linux-ide/20110426135027.GI878@htj.dyndns.org/

He even said:
"Hmm... it seems I wasn't thinking straight when I added that work around."
https://lore.kernel.org/linux-ide/20110426155229.GM878@htj.dyndns.org/

While removing the workaround solved the issue, however, the workaround was
kept to avoid "spurious hotplug events during reset", and instead another
workaround was added on top of the existing workaround in commit
8c56cacc724c ("libata: fix unexpectedly frozen port after ata_eh_reset()").

Because these IRQs happened when the port was frozen, we know that they
were actually a side effect of PxIS and IS.IPS(x) not being cleared before
the COMRESET. This is now done in commit 94152042eaa9 ("ata: libahci: clear
pending interrupt status"), so these workarounds can now be removed.

Since commit 1e641060c4b5 ("libata: clear eh_info on reset completion") has
now been reverted, the ATA EH retry mechanism is functional again, so there
is once again no need to thaw the port more than once in ata_eh_reset().

This reverts "the workaround on top of the workaround" introduced in commit
8c56cacc724c ("libata: fix unexpectedly frozen port after ata_eh_reset()").

Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
drivers/ata/libata-eh.c