path: root/drivers/net/wireless/ath/ath10k/htt_rx.c

/*
 * Copyright (c) 2005-2011 Atheros Communications Inc.
 * Copyright (c) 2011-2013 Qualcomm Atheros, Inc.
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include "core.h"
#include "htc.h"
#include "htt.h"
#include "txrx.h"
#include "debug.h"
#include "trace.h"

#include <linux/log2.h>

/* slightly larger than one large A-MPDU */
#define HTT_RX_RING_SIZE_MIN 128

/* roughly 20 ms @ 1 Gbps of 1500B MSDUs */
#define HTT_RX_RING_SIZE_MAX 2048

#define HTT_RX_AVG_FRM_BYTES 1000

/* ms, very conservative */
#define HTT_RX_HOST_LATENCY_MAX_MS 20

/* ms, conservative */
#define HTT_RX_HOST_LATENCY_WORST_LIKELY_MS 10

/* when under memory pressure rx ring refill may fail and needs a retry */
#define HTT_RX_RING_REFILL_RETRY_MS 50


static int ath10k_htt_rx_get_csum_state(struct sk_buff *skb);
static void ath10k_htt_txrx_compl_task(unsigned long ptr);

static int ath10k_htt_rx_ring_size(struct ath10k_htt *htt)
{
	int size;

	/*
	 * It is expected that the host CPU will typically be able to
	 * service the rx indication from one A-MPDU before the rx
	 * indication from the subsequent A-MPDU happens, roughly 1-2 ms
	 * later. However, the rx ring should be sized very conservatively,
	 * to accomodate the worst reasonable delay before the host CPU
	 * services a rx indication interrupt.
	 *
	 * The rx ring need not be kept full of empty buffers. In theory,
	 * the htt host SW can dynamically track the low-water mark in the
	 * rx ring, and dynamically adjust the level to which the rx ring
	 * is filled with empty buffers, to dynamically meet the desired
	 * low-water mark.
	 *
	 * In contrast, it's difficult to resize the rx ring itself, once
	 * it's in use. Thus, the ring itself should be sized very
	 * conservatively, while the degree to which the ring is filled
	 * with empty buffers should be sized moderately conservatively.
	 */

	/* 1e6 bps/mbps / 1e3 ms per sec = 1000 */
	size =
	    htt->max_throughput_mbps +
	    1000  /
	    (8 * HTT_RX_AVG_FRM_BYTES) * HTT_RX_HOST_LATENCY_MAX_MS;

	if (size < HTT_RX_RING_SIZE_MIN)
		size = HTT_RX_RING_SIZE_MIN;

	if (size > HTT_RX_RING_SIZE_MAX)
		size = HTT_RX_RING_SIZE_MAX;

	size = roundup_pow_of_two(size);

	return size;
}

static int ath10k_htt_rx_ring_fill_level(struct ath10k_htt *htt)
{
	int size;

	/* 1e6 bps/mbps / 1e3 ms per sec = 1000 */
	size =
	    htt->max_throughput_mbps *
	    1000  /
	    (8 * HTT_RX_AVG_FRM_BYTES) * HTT_RX_HOST_LATENCY_WORST_LIKELY_MS;

	/*
	 * Make sure the fill level is at least 1 less than the ring size.
	 * Leaving 1 element empty allows the SW to easily distinguish
	 * between a full ring vs. an empty ring.
	 */
	if (size >= htt