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Date: Thu, 29 Sep 2011 14:29:40 -0700
From: Alexander Duyck <alexander.h.duyck@...el.com>
To: Arnaud Lacombe <lacombar@...il.com>
CC: Jeff Kirsher <jeffrey.t.kirsher@...el.com>, davem@...emloft.net,
netdev@...r.kernel.org, gospo@...hat.com
Subject: Re: [net-next 1/9] igb: Update RXDCTL/TXDCTL configurations
This is due to a HW errata. Specifically HW errata 26 in the spec
update at
http://download.intel.com/design/network/specupdt/82576_SPECUPDATE.pdf.
It essentially states that write back does not occur on MSI-X interrupt
events so we need to keep WTHRESH at 1 in order to avoid any false hangs.
Thanks,
Alex
On 09/29/2011 10:41 AM, Arnaud Lacombe wrote:
> Hi,
>
> On Tue, Sep 20, 2011 at 3:11 AM, Jeff Kirsher
> <jeffrey.t.kirsher@...el.com> wrote:
>> From: Alexander Duyck<alexander.h.duyck@...el.com>
>>
>> This change cleans up the RXDCTL and TXDCTL configurations and optimizes RX
>> performance by allowing back write-backs on all hardware other than 82576.
>>
> Where does this limitation comes from ? The "Intel 82576EB GbE
> Controller - Programming Interface" from May 2011 advertises that both
> the RXDCTL and TXDCTL register have a 5bit wide WTHRESH field.
>
> Thanks,
> - Arnaud
>
>> Signed-off-by: Alexander Duyck<alexander.h.duyck@...el.com>
>> Tested-by: Aaron Brown<aaron.f.brown@...el.com>
>> Signed-off-by: Jeff Kirsher<jeffrey.t.kirsher@...el.com>
>> ---
>> drivers/net/ethernet/intel/igb/igb.h | 5 +++--
>> drivers/net/ethernet/intel/igb/igb_main.c | 23 +++++++++--------------
>> 2 files changed, 12 insertions(+), 16 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/intel/igb/igb.h b/drivers/net/ethernet/intel/igb/igb.h
>> index 265e151..577fd3e 100644
>> --- a/drivers/net/ethernet/intel/igb/igb.h
>> +++ b/drivers/net/ethernet/intel/igb/igb.h
>> @@ -100,11 +100,12 @@ struct vf_data_storage {
>> */
>> #define IGB_RX_PTHRESH 8
>> #define IGB_RX_HTHRESH 8
>> -#define IGB_RX_WTHRESH 1
>> #define IGB_TX_PTHRESH 8
>> #define IGB_TX_HTHRESH 1
>> +#define IGB_RX_WTHRESH ((hw->mac.type == e1000_82576&& \
>> + adapter->msix_entries) ? 1 : 4)
>> #define IGB_TX_WTHRESH ((hw->mac.type == e1000_82576&& \
>> - adapter->msix_entries) ? 1 : 16)
>> + adapter->msix_entries) ? 1 : 16)
>>
>> /* this is the size past which hardware will drop packets when setting LPE=0 */
>> #define MAXIMUM_ETHERNET_VLAN_SIZE 1522
>> diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
>> index 3cb1bc9..aa78c10 100644
>> --- a/drivers/net/ethernet/intel/igb/igb_main.c
>> +++ b/drivers/net/ethernet/intel/igb/igb_main.c
>> @@ -2666,14 +2666,12 @@ void igb_configure_tx_ring(struct igb_adapter *adapter,
>> struct igb_ring *ring)
>> {
>> struct e1000_hw *hw =&adapter->hw;
>> - u32 txdctl;
>> + u32 txdctl = 0;
>> u64 tdba = ring->dma;
>> int reg_idx = ring->reg_idx;
>>
>> /* disable the queue */
>> - txdctl = rd32(E1000_TXDCTL(reg_idx));
>> - wr32(E1000_TXDCTL(reg_idx),
>> - txdctl& ~E1000_TXDCTL_QUEUE_ENABLE);
>> + wr32(E1000_TXDCTL(reg_idx), 0);
>> wrfl();
>> mdelay(10);
>>
>> @@ -2685,7 +2683,7 @@ void igb_configure_tx_ring(struct igb_adapter *adapter,
>>
>> ring->head = hw->hw_addr + E1000_TDH(reg_idx);
>> ring->tail = hw->hw_addr + E1000_TDT(reg_idx);
>> - writel(0, ring->head);
>> + wr32(E1000_TDH(reg_idx), 0);
>> writel(0, ring->tail);
>>
>> txdctl |= IGB_TX_PTHRESH;
>> @@ -3028,12 +3026,10 @@ void igb_configure_rx_ring(struct igb_adapter *adapter,
>> struct e1000_hw *hw =&adapter->hw;
>> u64 rdba = ring->dma;
>> int reg_idx = ring->reg_idx;
>> - u32 srrctl, rxdctl;
>> + u32 srrctl = 0, rxdctl = 0;
>>
>> /* disable the queue */
>> - rxdctl = rd32(E1000_RXDCTL(reg_idx));
>> - wr32(E1000_RXDCTL(reg_idx),
>> - rxdctl& ~E1000_RXDCTL_QUEUE_ENABLE);
>> + wr32(E1000_RXDCTL(reg_idx), 0);
>>
>> /* Set DMA base address registers */
>> wr32(E1000_RDBAL(reg_idx),
>> @@ -3045,7 +3041,7 @@ void igb_configure_rx_ring(struct igb_adapter *adapter,
>> /* initialize head and tail */
>> ring->head = hw->hw_addr + E1000_RDH(reg_idx);
>> ring->tail = hw->hw_addr + E1000_RDT(reg_idx);
>> - writel(0, ring->head);
>> + wr32(E1000_RDH(reg_idx), 0);
>> writel(0, ring->tail);
>>
>> /* set descriptor configuration */
>> @@ -3076,13 +3072,12 @@ void igb_configure_rx_ring(struct igb_adapter *adapter,
>> /* set filtering for VMDQ pools */
>> igb_set_vmolr(adapter, reg_idx& 0x7, true);
>>
>> - /* enable receive descriptor fetching */
>> - rxdctl = rd32(E1000_RXDCTL(reg_idx));
>> - rxdctl |= E1000_RXDCTL_QUEUE_ENABLE;
>> - rxdctl&= 0xFFF00000;
>> rxdctl |= IGB_RX_PTHRESH;
>> rxdctl |= IGB_RX_HTHRESH<< 8;
>> rxdctl |= IGB_RX_WTHRESH<< 16;
>> +
>> + /* enable receive descriptor fetching */
>> + rxdctl |= E1000_RXDCTL_QUEUE_ENABLE;
>> wr32(E1000_RXDCTL(reg_idx), rxdctl);
>> }
>>
>> --
>> 1.7.6.2
>>
>> --
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