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authorDan Williams <dan.j.williams@intel.com>2019-08-30 02:30:34 +0300
committerJens Axboe <axboe@kernel.dk>2019-08-31 05:53:42 +0300
commitc312ef176399e04fc5f7f2809d9a589751fbf6d9 (patch)
tree02a399c6462bd35d021066441315e887a2316823 /drivers/ata/ahci.h
parent60fc35f327e0a9e60b955c0f3c3ed623608d1baa (diff)
downloadlinux-c312ef176399e04fc5f7f2809d9a589751fbf6d9.tar.xz
libata/ahci: Drop PCS quirk for Denverton and beyond
The Linux ahci driver has historically implemented a configuration fixup for platforms / platform-firmware that fails to enable the ports prior to OS hand-off at boot. The fixup was originally implemented way back before ahci moved from drivers/scsi/ to drivers/ata/, and was updated in 2007 via commit 49f290903935 "ahci: update PCS programming". The quirk sets a port-enable bitmap in the PCS register at offset 0x92. This quirk could be applied generically up until the arrival of the Denverton (DNV) platform. The DNV AHCI controller architecture supports more than 6 ports and along with that the PCS register location and format were updated to allow for more possible ports in the bitmap. DNV AHCI expands the register to 32-bits and moves it to offset 0x94. As it stands there are no known problem reports with existing Linux trying to set bits at offset 0x92 which indicates that the quirk is not applicable. Likely it is not applicable on a wider range of platforms, but it is difficult to discern which platforms if any still depend on the quirk. Rather than try to fix the PCS quirk to consider the DNV register layout instead require explicit opt-in. The assumption is that the OS driver need not touch this register, and platforms can be added with a new boad_ahci_pcs7 board-id when / if problematic platforms are found in the future. The logic in ahci_intel_pcs_quirk() looks for all Intel AHCI instances with "legacy" board-ids and otherwise skips the quirk if the board was matched by class-code. Reported-by: Stephen Douthit <stephend@silicom-usa.com> Cc: Christoph Hellwig <hch@infradead.org> Reviewed-by: Stephen Douthit <stephend@silicom-usa.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers/ata/ahci.h')
-rw-r--r--drivers/ata/ahci.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/ata/ahci.h b/drivers/ata/ahci.h
index 0570629d719d..3dbf398c92ea 100644
--- a/drivers/ata/ahci.h
+++ b/drivers/ata/ahci.h
@@ -247,6 +247,8 @@ enum {
ATA_FLAG_ACPI_SATA | ATA_FLAG_AN,
ICH_MAP = 0x90, /* ICH MAP register */
+ PCS_6 = 0x92, /* 6 port PCS */
+ PCS_7 = 0x94, /* 7+ port PCS (Denverton) */
/* em constants */
EM_MAX_SLOTS = 8,