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authorJoerg Roedel <joerg.roedel@amd.com>2008-08-14 19:55:15 +0200
committerIngo Molnar <mingo@elte.hu>2008-08-15 13:56:46 +0200
commit519c31bacf78a969efa8d2e55ed8862848f28590 (patch)
treebbeb4cd9f810536beb3bb1c5e6a827fa35a37633 /arch/x86/kernel/amd_iommu.c
parentb635acec48bcaa9183fcbf4e3955616b0d4119b5 (diff)
downloadlwn-519c31bacf78a969efa8d2e55ed8862848f28590.tar.gz
lwn-519c31bacf78a969efa8d2e55ed8862848f28590.zip
x86, AMD IOMMU: use status bit instead of memory write-back for completion wait
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel/amd_iommu.c')
-rw-r--r--arch/x86/kernel/amd_iommu.c17
1 files changed, 10 insertions, 7 deletions
diff --git a/arch/x86/kernel/amd_iommu.c b/arch/x86/kernel/amd_iommu.c
index 22d7d050905d..028e945c68ad 100644
--- a/arch/x86/kernel/amd_iommu.c
+++ b/arch/x86/kernel/amd_iommu.c
@@ -101,16 +101,13 @@ static int iommu_queue_command(struct amd_iommu *iommu, struct iommu_cmd *cmd)
*/
static int iommu_completion_wait(struct amd_iommu *iommu)
{
- int ret;
+ int ret, ready = 0;
+ unsigned status = 0;
struct iommu_cmd cmd;
- volatile u64 ready = 0;
- unsigned long ready_phys = virt_to_phys(&ready);
unsigned long i = 0;
memset(&cmd, 0, sizeof(cmd));
- cmd.data[0] = LOW_U32(ready_phys) | CMD_COMPL_WAIT_STORE_MASK;
- cmd.data[1] = upper_32_bits(ready_phys);
- cmd.data[2] = 1; /* value written to 'ready' */
+ cmd.data[0] = CMD_COMPL_WAIT_INT_MASK;
CMD_SET_TYPE(&cmd, CMD_COMPL_WAIT);
iommu->need_sync = 0;
@@ -122,9 +119,15 @@ static int iommu_completion_wait(struct amd_iommu *iommu)
while (!ready && (i < EXIT_LOOP_COUNT)) {
++i;
- cpu_relax();
+ /* wait for the bit to become one */
+ status = readl(iommu->mmio_base + MMIO_STATUS_OFFSET);
+ ready = status & MMIO_STATUS_COM_WAIT_INT_MASK;
}
+ /* set bit back to zero */
+ status &= ~MMIO_STATUS_COM_WAIT_INT_MASK;
+ writel(status, iommu->mmio_base + MMIO_STATUS_OFFSET);
+
if (unlikely((i == EXIT_LOOP_COUNT) && printk_ratelimit()))
printk(KERN_WARNING "AMD IOMMU: Completion wait loop failed\n");