ioat3: dca and raid operations are incompatible

RAID operations cause a system hang on platforms with DCA
(Direct-Cache-Access) enabled.  So turn off RAID capabilities in this
case.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/dma/ioat/dca.c b/drivers/dma/ioat/dca.c
index 14f0a782df44a224dc5cce3c6f64ef58f9049b2e..abd9038e06b1351ab7706c81fcbd96e8dbf2eebd 100644 (file)
--- a/drivers/dma/ioat/dca.c
+++ b/drivers/dma/ioat/dca.c
@@ -103,7 +103,7 @@ static int dca_enabled_in_bios(struct pci_dev *pdev)
        return res;
 }
 
-static int system_has_dca_enabled(struct pci_dev *pdev)
+int system_has_dca_enabled(struct pci_dev *pdev)
 {
        if (boot_cpu_has(X86_FEATURE_DCA))
                return dca_enabled_in_bios(pdev);

diff --git a/drivers/dma/ioat/dma_v3.c b/drivers/dma/ioat/dma_v3.c
index 35d1e33afd5b9c3bf7a185d3f9df5b37747dacf6..4f305f61f8784fe5c23494fecc542e5dccbc43a2 100644 (file)
--- a/drivers/dma/ioat/dma_v3.c
+++ b/drivers/dma/ioat/dma_v3.c
@@ -1117,6 +1117,7 @@ static int __devinit ioat3_dma_self_test(struct ioatdma_device *device)
 int __devinit ioat3_dma_probe(struct ioatdma_device *device, int dca)
 {
        struct pci_dev *pdev = device->pdev;
+       int dca_en = system_has_dca_enabled(pdev);
        struct dma_device *dma;
        struct dma_chan *c;
        struct ioat_chan_common *chan;
@@ -1137,6 +1138,11 @@ int __devinit ioat3_dma_probe(struct ioatdma_device *device, int dca)
        dma->device_prep_dma_interrupt = ioat3_prep_interrupt_lock;
 
        cap = readl(device->reg_base + IOAT_DMA_CAP_OFFSET);
+
+       /* dca is incompatible with raid operations */
+       if (dca_en && (cap & (IOAT_CAP_XOR|IOAT_CAP_PQ)))
+               cap &= ~(IOAT_CAP_XOR|IOAT_CAP_PQ);
+
        if (cap & IOAT_CAP_XOR) {
                is_raid_device = true;
                dma->max_xor = 8;

diff --git a/drivers/dma/ioat/hw.h b/drivers/dma/ioat/hw.h
index 99afb12bd4093fe862006111ebe1b8a560abe26f..60e675455b6aa13d10aef2fe50b753fbe0a5942d 100644 (file)
--- a/drivers/dma/ioat/hw.h
+++ b/drivers/dma/ioat/hw.h
@@ -39,6 +39,8 @@
 #define IOAT_VER_3_0            0x30    /* Version 3.0 */
 #define IOAT_VER_3_2            0x32    /* Version 3.2 */
 
+int system_has_dca_enabled(struct pci_dev *pdev);
+
 struct ioat_dma_descriptor {
        uint32_t        size;
        union {