| Message ID | 20190610212750.173711-1-venkateshs@google.com |
|---|---|
| State | Accepted |
| Delegated to: | Jeff Kirsher |
| Headers | show |
| Series | e1000: Use dma_wmb() instead of wmb() before doorbell writes | expand |
> From: Intel-wired-lan [mailto:intel-wired-lan-bounces@osuosl.org] On > Behalf Of Venkatesh Srinivas > Sent: Monday, June 10, 2019 2:28 PM > To: Kirsher, Jeffrey T <jeffrey.t.kirsher@intel.com> > Cc: intel-wired-lan@osuosl.org; vsrinivas@ops101.org > Subject: [Intel-wired-lan] [PATCH] e1000: Use dma_wmb() instead of wmb() > before doorbell writes > > e1000 writes to doorbells to post transmit descriptors and fill the > receive ring. After writing descriptors to memory but before > writing to doorbells, use dma_wmb() rather than wmb(). wmb() is more > heavyweight than necessary for a device to see descriptor writes. > > On x86, this avoids SFENCEs before doorbell writes in both the > tx and rx paths. On ARM, this converts DSB ST -> DMB OSHST. > > Tested: 82576EB / x86; QEMU (qemu emulates an 8257x) > > Signed-off-by: Venkatesh Srinivas <venkateshs@google.com> > --- > drivers/net/ethernet/intel/e1000/e1000_main.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > Tested-by: Aaron Brown <aaron.f.brown@intel.com> Tested with a handful of physical parts that I still have laying around just for this purpose, 82540EM, multiple 82541PI, 82541GI, 82543GC, multiple 82544GC, ...
diff --git a/drivers/net/ethernet/intel/e1000/e1000_main.c b/drivers/net/ethernet/intel/e1000/e1000_main.c index 551de8c2fef2..f703fa58458e 100644 --- a/drivers/net/ethernet/intel/e1000/e1000_main.c +++ b/drivers/net/ethernet/intel/e1000/e1000_main.c @@ -3019,7 +3019,7 @@ static void e1000_tx_queue(struct e1000_adapter *adapter, * applicable for weak-ordered memory model archs, * such as IA-64). */ - wmb(); + dma_wmb(); tx_ring->next_to_use = i; } @@ -4540,7 +4540,7 @@ e1000_alloc_jumbo_rx_buffers(struct e1000_adapter *adapter, * applicable for weak-ordered memory model archs, * such as IA-64). */ - wmb(); + dma_wmb(); writel(i, adapter->hw.hw_addr + rx_ring->rdt); } } @@ -4655,7 +4655,7 @@ static void e1000_alloc_rx_buffers(struct e1000_adapter *adapter, * applicable for weak-ordered memory model archs, * such as IA-64). */ - wmb(); + dma_wmb(); writel(i, hw->hw_addr + rx_ring->rdt); } }
e1000 writes to doorbells to post transmit descriptors and fill the receive ring. After writing descriptors to memory but before writing to doorbells, use dma_wmb() rather than wmb(). wmb() is more heavyweight than necessary for a device to see descriptor writes. On x86, this avoids SFENCEs before doorbell writes in both the tx and rx paths. On ARM, this converts DSB ST -> DMB OSHST. Tested: 82576EB / x86; QEMU (qemu emulates an 8257x) Signed-off-by: Venkatesh Srinivas <venkateshs@google.com> --- drivers/net/ethernet/intel/e1000/e1000_main.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)