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authorAlexander Gordeev <agordeev@redhat.com>2014-04-17 14:13:49 +0200
committerTejun Heo <tj@kernel.org>2014-04-17 09:58:48 -0400
commitab0f9e78b97f5193dd38b3757b42b6fbded05fb7 (patch)
treeef358a2498af2079aca6d954aac66aebf731adb2
parent9ae794ac5e407d3bc3fec785db481d5a2c0fa275 (diff)
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 <agordeev@redhat.com> Cc: linux-ide@vger.kernel.org Cc: stable@vger.kernel.org Signed-off-by: Tejun Heo <tj@kernel.org>
-rw-r--r--drivers/ata/ahci.c9
-rw-r--r--drivers/ata/ahci.h1
2 files changed, 9 insertions, 1 deletions
diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index e45b18ee04c3..f6b3e31f63cd 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -1164,7 +1164,7 @@ static inline void ahci_gtf_filter_workaround(struct ata_host *host)
#endif
static int ahci_init_interrupts(struct pci_dev *pdev, unsigned int n_ports,
- struct ahci_host_priv *hpriv)
+ struct ahci_host_priv *hpriv)
{
int nvec;
@@ -1189,6 +1189,13 @@ static int ahci_init_interrupts(struct pci_dev *pdev, unsigned int n_ports,
else if (nvec < 0)
goto intx;
+ /* fallback to single MSI mode if the controller enforced MRSM mode */
+ if (readl(hpriv->mmio + HOST_CTL) & HOST_MRSM) {
+ pci_disable_msi(pdev);
+ printk(KERN_INFO "ahci: MRSM is on, fallback to single MSI\n");
+ goto single_msi;
+ }
+
return nvec;
single_msi:
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 */