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e1000e: Remove duplicated writel() in e1000_configure_tx/rx()

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Duplicated register initialization codes exist in e1000_configure_tx()
and e1000_configure_rx().

For example, writel(0, tx_ring->head) writes 0 to tx_ring->head, which
is adapter->hw.hw_addr + E1000_TDH(0).

This initialization is already done in ew32(TDH(0), 0).

ew32(TDH(0), 0) is equivalent to __ew32(hw, E1000_TDH(0), 0). It
executes writel(0, hw->hw_addr + E1000_TDH(0)). Since variable hw is
set to &adapter->hw, it is equal to writel(0, tx_ring->head).

We can remove similar four writel() in e1000_configure_tx() and
e1000_configure_rx().

commit 0845d45e90 ("e1000e: Modify Tx/Rx configurations to avoid
null pointer dereferences in e1000_open") has introduced these
writel(). This commit moved register writing to
e1000_configure_tx/rx(), and as result, it caused duplication in
e1000_configure_tx/rx().

This patch modifies the sequence of register writing, but removing
these writes is safe because the same writes were already there before
the commit.

I also have checked the datasheets [0] [1] and have not found any
description that we need to write RDH, RDT, TDH and TDT registers
twice at initialization. Furthermore, we have tested this patch on an
I219-V device physically.

Link: https://www.intel.com/content/dam/www/public/us/en/documents/datasheets/82577-gbe-phy-datasheet.pdf [0]
Link: https://www.intel.com/content/www/us/en/content-details/613460/intel-82583v-gbe-controller-datasheet.html [1]
Tested-by: Kohei Enju <enjuk@amazon.com>
Signed-off-by: Takamitsu Iwai <takamitz@amazon.co.jp>
Tested-by: Mor Bar-Gabay <morx.bar.gabay@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
This commit is contained in:
Takamitsu Iwai 2024-09-06 11:17:19 +09:00 committed by Tony Nguyen
parent c3c50d4c62
commit 0cab3b0f83
1 changed files with 0 additions and 6 deletions
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6
drivers/net/ethernet/intel/e1000e/netdev.c
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@ -2928,11 +2928,8 @@ static void e1000_configure_tx(struct e1000_adapter *adapter)
tx_ring->head = adapter->hw.hw_addr + E1000_TDH(0);
tx_ring->tail = adapter->hw.hw_addr + E1000_TDT(0);
writel(0, tx_ring->head);
if (adapter->flags2 & FLAG2_PCIM2PCI_ARBITER_WA)
e1000e_update_tdt_wa(tx_ring, 0);
else
writel(0, tx_ring->tail);
/* Set the Tx Interrupt Delay register */
ew32(TIDV, adapter->tx_int_delay);
@ -3253,11 +3250,8 @@ static void e1000_configure_rx(struct e1000_adapter *adapter)
rx_ring->head = adapter->hw.hw_addr + E1000_RDH(0);
rx_ring->tail = adapter->hw.hw_addr + E1000_RDT(0);
writel(0, rx_ring->head);
if (adapter->flags2 & FLAG2_PCIM2PCI_ARBITER_WA)
e1000e_update_rdt_wa(rx_ring, 0);
else
writel(0, rx_ring->tail);
/* Enable Receive Checksum Offload for TCP and UDP */
rxcsum = er32(RXCSUM);