bnxt_en: Fix TX timeout when TX ring size is set to the smallest

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The smallest TX ring size we support must fit a TX SKB with MAX_SKB_FRAGS
+ 1.  Because the first TX BD for a packet is always a long TX BD, we
need an extra TX BD to fit this packet.  Define BNXT_MIN_TX_DESC_CNT with
this value to make this more clear.  The current code uses a minimum
that is off by 1.  Fix it using this constant.

The tx_wake_thresh to determine when to wake up the TX queue is half the
ring size but we must have at least BNXT_MIN_TX_DESC_CNT for the next
packet which may have maximum fragments.  So the comparison of the
available TX BDs with tx_wake_thresh should be >= instead of > in the
current code.  Otherwise, at the smallest ring size, we will never wake
up the TX queue and will cause TX timeout.

Fixes: c0c050c58d ("bnxt_en: New Broadcom ethernet driver.")
Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadocm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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This commit is contained in:

Michael Chan 2021-09-20 02:51:52 -04:00 • committed by David S. Miller

parent 563f23b002

commit 5bed8b0704

3 changed files with 10 additions and 5 deletions

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8

drivers/net/ethernet/broadcom/bnxt/bnxt.c

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5

drivers/net/ethernet/broadcom/bnxt/bnxt.h

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2

drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c

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