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(-)
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