Re: [PATCH 2.6.25-rc6] sata_promise: fix hardreset hotplug events, take 2

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Mikael Pettersson wrote:
A Promise SATA controller will signal hotplug events when a hard
reset (COMRESET) is done on a port. These events aren't masked by
the driver, and the unexpected interrupts will cause a sequence
of failed reset attempts util libata's EH finally gives up.

This has not been a common problem so far, but the pending libata
hardreset-by-default changes makes it a critical issue.

The solution is to disable hotplug events before a reset, and to
reenable them afterwards. (Promise's driver does this too.)

This patch adds SATA-specific versions of ->freeze() and ->thaw()
that also disable and enable hotplug events. PATA ports continue
to use the old versions of ->freeze() and ->thaw().

Accesses to the hotplug register must be serialised via host->lock.
We rely on ap->lock == &ap->host->lock and that libata takes this
lock before ->freeze() and ->thaw(). Document this requirement.
The interrupt handler is adjusted so its hotplug register accesses
are inside the region protected by host->lock.

Tested on various chips (SATA300TX4, SATA300TX2plus, SATAII150TX4,
FastTrack TX4000) with various combinations of SATA and PATA disks,
with and without the pending hardreset-by-default changes.

Signed-off-by: Mikael Pettersson <mikpe@xxxxxxxx>
---
Changes since previous version:
- rephrase the problem description to avoid calling it a HW quirk,
  the behaviour is apparently standard
- fix double locking bug found by Tejun, now tested with SMP kernel
- document locking rules for the global hotplug register
- inline the hotplug enable/disable code in freeze/thaw

 drivers/ata/sata_promise.c |  109 ++++++++++++++++++++++++++++++++++++---------
 1 file changed, 88 insertions(+), 21 deletions(-)

applied


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