diff mbox series

[net-next,10/12] e1000e: Remove duplicated writel() in e1000_configure_tx/rx()

Message ID 20241008233441.928802-11-anthony.l.nguyen@intel.com (mailing list archive)
State Accepted
Commit 0cab3b0f8306a9ecd11b4c72ca4b890ae816193c
Delegated to: Netdev Maintainers
Headers show
Series Intel Wired LAN Driver Updates 2024-10-08 (ice, iavf, igb, e1000e, e1000) | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 6 this patch: 6
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 4 of 4 maintainers
netdev/build_clang success Errors and warnings before: 6 this patch: 6
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 5 this patch: 5
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 22 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 35 this patch: 35
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2024-10-10--03-00 (tests: 773)

Commit Message

Tony Nguyen Oct. 8, 2024, 11:34 p.m. UTC 
From: Takamitsu Iwai <takamitz@amazon.co.jp>

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 0845d45e900c ("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>
---
 drivers/net/ethernet/intel/e1000e/netdev.c | 6 ------
 1 file changed, 6 deletions(-)
diff mbox series

Patch

diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
index f103249b12fa..9c9d4cb7c735 100644
--- a/drivers/net/ethernet/intel/e1000e/netdev.c
+++ b/drivers/net/ethernet/intel/e1000e/netdev.c
@@ -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);