From 86c432ca5d6da90a26ac8d3e680f2268b502d9c5 Mon Sep 17 00:00:00 2001 From: Ben Hutchings Date: Thu, 1 Sep 2011 12:09:29 +0000 Subject: Revert "sfc: Use write-combining to reduce TX latency" and follow-ups This reverts commits 65f0b417dee94f779ce9b77102b7d73c93723b39, d88d6b05fee3cc78e5b0273eb58c31201dcc6b76, fcfa060468a4edcf776f0c1211d826d5de1668c1, 747df2258b1b9a2e25929ef496262c339c380009 and 867955f5682f7157fdafe8670804b9f8ea077bc7. Depending on the processor model, write-combining may result in reordering that the NIC will not tolerate. This typically results in a DMA error event and reset by the driver, logged as: sfc 0000:0e:00.0: eth2: TX DMA Q reports TX_EV_PKT_ERR. sfc 0000:0e:00.0: eth2: resetting (ALL) Signed-off-by: Ben Hutchings Signed-off-by: David S. Miller --- drivers/net/sfc/efx.c | 18 ++---------------- 1 file changed, 2 insertions(+), 16 deletions(-) (limited to 'drivers/net/sfc/efx.c') diff --git a/drivers/net/sfc/efx.c b/drivers/net/sfc/efx.c index faca764aa21..b59abc706d9 100644 --- a/drivers/net/sfc/efx.c +++ b/drivers/net/sfc/efx.c @@ -1050,7 +1050,6 @@ 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"); @@ -1101,21 +1100,8 @@ static int efx_init_io(struct efx_nic *efx) rc = -EIO; goto fail3; } - - /* 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); + 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", -- cgit v1.2.3-70-g09d2