sfc: Siena: Disable write-combining when SR-IOV is enabled

If SR-IOV is enabled by firmware, even if it is not enabled in the PCI
capability, TX pushes using write-combining may be corrupted.

We want to know whether it is enabled before mapping the NIC
registers, and even if PCI extended capabilities are not accessible.
Therefore, we look for the MSI capability, which is removed if SR-IOV
is enabled.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>

diff --git a/drivers/net/sfc/efx.c b/drivers/net/sfc/efx.c
index b8bd936374f29e5142deb4d75f4ec700af42a5bf..d890679e4c4d293538b0e8d98cb1f34466e23947 100644 (file)
--- a/drivers/net/sfc/efx.c
+++ b/drivers/net/sfc/efx.c
@@ -1054,6 +1054,7 @@ static int efx_init_io(struct efx_nic *efx)
 {
        struct pci_dev *pci_dev = efx->pci_dev;
        dma_addr_t dma_mask = efx->type->max_dma_mask;
+       bool use_wc;
        int rc;
 
        netif_dbg(efx, probe, efx->net_dev, "initialising I/O\n");
@@ -1104,8 +1105,21 @@ static int efx_init_io(struct efx_nic *efx)
                rc = -EIO;
                goto fail3;
        }
-       efx->membase = ioremap_wc(efx->membase_phys,
-                                 efx->type->mem_map_size);
+
+       /* bug22643: If SR-IOV is enabled then tx push over a write combined
+        * mapping is unsafe. We need to disable write combining in this case.
+        * MSI is unsupported when SR-IOV is enabled, and the firmware will
+        * have removed the MSI capability. So write combining is safe if
+        * there is an MSI capability.
+        */
+       use_wc = (!EFX_WORKAROUND_22643(efx) ||
+                 pci_find_capability(pci_dev, PCI_CAP_ID_MSI));
+       if (use_wc)
+               efx->membase = ioremap_wc(efx->membase_phys,
+                                         efx->type->mem_map_size);
+       else
+               efx->membase = ioremap_nocache(efx->membase_phys,
+                                              efx->type->mem_map_size);
        if (!efx->membase) {
                netif_err(efx, probe, efx->net_dev,
                          "could not map memory BAR at %llx+%x\n",

diff --git a/drivers/net/sfc/workarounds.h b/drivers/net/sfc/workarounds.h
index e4dd3a7f304b5b70e874530fda18d251cc4515b1..99ff11400cef646458279500b3b230b804c4be8d 100644 (file)
--- a/drivers/net/sfc/workarounds.h
+++ b/drivers/net/sfc/workarounds.h
@@ -38,6 +38,8 @@
 #define EFX_WORKAROUND_15783 EFX_WORKAROUND_ALWAYS
 /* Legacy interrupt storm when interrupt fifo fills */
 #define EFX_WORKAROUND_17213 EFX_WORKAROUND_SIENA
+/* Write combining and sriov=enabled are incompatible */
+#define EFX_WORKAROUND_22643 EFX_WORKAROUND_SIENA
 
 /* Spurious parity errors in TSORT buffers */
 #define EFX_WORKAROUND_5129 EFX_WORKAROUND_FALCON_A