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Revision 92214be5979c0961a471b7eaaaeacab41bdf456c authored by Rahul Rameshbabu on 14 November 2023, 21:58:42 UTC, committed by Jakub Kicinski on 16 November 2023, 06:34:31 UTC 
net/mlx5e: Update doorbell for port timestamping CQ before the software counter
 
Previously, mlx5e_ptp_poll_ts_cq would update the device doorbell with the
incremented consumer index after the relevant software counters in the
kernel were updated. In the mlx5e_sq_xmit_wqe context, this would lead to
either overrunning the device CQ or exceeding the expected software buffer
size in the device CQ if the device CQ size was greater than the software
buffer size. Update the relevant software counter only after updating the
device CQ consumer index in the port timestamping napi_poll context.

Log:
    mlx5_core 0000:08:00.0: cq_err_event_notifier:517:(pid 0): CQ error on CQN 0x487, syndrome 0x1
    mlx5_core 0000:08:00.0 eth2: mlx5e_cq_error_event: cqn=0x000487 event=0x04

Fixes: 1880bc4e4a96 ("net/mlx5e: Add TX port timestamp support")
Signed-off-by: Rahul Rameshbabu <rrameshbabu@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Link: https://lore.kernel.org/r/20231114215846.5902-12-saeed@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
1 parent 7e3f3ba
Raw File
crc4.c 
// SPDX-License-Identifier: GPL-2.0-only
/*
 * crc4.c - simple crc-4 calculations.
 */

#include <linux/crc4.h>
#include <linux/module.h>

static const uint8_t crc4_tab[] = {
	0x0, 0x7, 0xe, 0x9, 0xb, 0xc, 0x5, 0x2,
	0x1, 0x6, 0xf, 0x8, 0xa, 0xd, 0x4, 0x3,
};

/**
 * crc4 - calculate the 4-bit crc of a value.
 * @c:    starting crc4
 * @x:    value to checksum
 * @bits: number of bits in @x to checksum
 *
 * Returns the crc4 value of @x, using polynomial 0b10111.
 *
 * The @x value is treated as left-aligned, and bits above @bits are ignored
 * in the crc calculations.
 */
uint8_t crc4(uint8_t c, uint64_t x, int bits)
{
	int i;

	/* mask off anything above the top bit */
	x &= (1ull << bits) - 1;

	/* Align to 4-bits */
	bits = (bits + 3) & ~0x3;

	/* Calculate crc4 over four-bit nibbles, starting at the MSbit */
	for (i = bits - 4; i >= 0; i -= 4)
		c = crc4_tab[c ^ ((x >> i) & 0xf)];

	return c;
}
EXPORT_SYMBOL_GPL(crc4);

MODULE_DESCRIPTION("CRC4 calculations");
MODULE_LICENSE("GPL");
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