From ab0f9e78b97f5193dd38b3757b42b6fbded05fb7 Mon Sep 17 00:00:00 2001 From: Alexander Gordeev Date: Thu, 17 Apr 2014 14:13:49 +0200 Subject: ahci: Ensure "MSI Revert to Single Message" mode is not enforced The AHCI specification allows hardware to choose to revert to single MSI mode when fewer messages are allocated than requested. Yet, at least ICH10 chipset reverts to single MSI mode even when enough messages are allocated in some cases (see below). This update forces the driver to not rely on initialization of multiple MSIs mode alone and always check if "MSI Revert to Single Message" (MRSM) mode was enforced by the controller and fallback to the single MSI mode in case it did. That prevents a situation when the driver configured multiple per-port IRQ handlers, but the controller sends all port's interrupts to a single IRQ, which could easily screw up the interrupt handling and lead to delays and possibly crashes. The fix was tested on a 6-port controller that successfully reverted to the single MSI mode: 00:1f.2 SATA controller: Intel Corporation 82801JI (ICH10 Family) SATA AHCI Controller (prog-if 01 [AHCI 1.0]) Subsystem: Super Micro Computer Inc Device 10a7 Flags: bus master, 66MHz, medium devsel, latency 0, IRQ 101 I/O ports at f110 [size=8] I/O ports at f100 [size=4] I/O ports at f0f0 [size=8] I/O ports at f0e0 [size=4] I/O ports at f020 [size=32] Memory at fbf00000 (32-bit, non-prefetchable) [size=2K] Capabilities: [80] MSI: Enable+ Count=1/16 Maskable- 64bit- Capabilities: [70] Power Management version 3 Capabilities: [a8] SATA HBA v1.0 Capabilities: [b0] PCI Advanced Features Kernel driver in use: ahci With 6 ports just 8 MSI vectors should be enough, but the adapter enforces the MRSM mode when less than 16 vectors are written to the Multiple Messages Enable PCI register. I instigated MRSM mode by forcing @nvec to 8 in ahci_init_interrupts(). Signed-off-by: Alexander Gordeev Cc: linux-ide@vger.kernel.org Cc: stable@vger.kernel.org Signed-off-by: Tejun Heo --- drivers/ata/ahci.h | 1 + 1 file changed, 1 insertion(+) (limited to 'drivers/ata/ahci.h') diff --git a/drivers/ata/ahci.h b/drivers/ata/ahci.h index 51af275b3388..b5eb886da226 100644 --- a/drivers/ata/ahci.h +++ b/drivers/ata/ahci.h @@ -94,6 +94,7 @@ enum { /* HOST_CTL bits */ HOST_RESET = (1 << 0), /* reset controller; self-clear */ HOST_IRQ_EN = (1 << 1), /* global IRQ enable */ + HOST_MRSM = (1 << 2), /* MSI Revert to Single Message */ HOST_AHCI_EN = (1 << 31), /* AHCI enabled */ /* HOST_CAP bits */ -- cgit v1.2.3-70-g09d2