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Commit fe2407a8 authored by Michal Kazior's avatar Michal Kazior Committed by Kalle Valo
Browse files

ath10k: simplify rx ring size/fill calculation 



Don't bother with fancy arithmetic and just
hardcode the final values.

Signed-off-by: default avatarMichal Kazior <michal.kazior@tieto.com>
Signed-off-by: default avatarKalle Valo <kvalo@qca.qualcomm.com>
parent 1cb86d47

drivers/net/wireless/ath/ath10k/htt.h

+3 −0
Original line number Diff line number Diff line
@@ -158,6 +158,9 @@ enum htt_rx_ring_flags { 
	HTT_RX_RING_FLAGS_PHY_DATA_RX  = 1 << 15

};



#define HTT_RX_RING_SIZE_MIN 128

#define HTT_RX_RING_SIZE_MAX 2048



struct htt_rx_ring_setup_ring {

	__le32 fw_idx_shadow_reg_paddr;

	__le32 rx_ring_base_paddr;

drivers/net/wireless/ath/ath10k/htt_rx.c

+9 −89
Original line number Diff line number Diff line
@@ -25,19 +25,8 @@ 


#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

#define HTT_RX_RING_SIZE 1024

#define HTT_RX_RING_FILL_LEVEL 1000



/* when under memory pressure rx ring refill may fail and needs a retry */

#define HTT_RX_RING_REFILL_RETRY_MS 50
@@ -45,68 +34,6 @@ 
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->rx_ring.size)

		size = htt->rx_ring.size - 1;



	return size;

}



static void ath10k_htt_rx_ring_free(struct ath10k_htt *htt)

{

	struct sk_buff *skb;
@@ -462,25 +389,18 @@ int ath10k_htt_rx_alloc(struct ath10k_htt *htt) 


	htt->rx_confused = false;



	htt->rx_ring.size = ath10k_htt_rx_ring_size(htt);

	/* XXX: The fill level could be changed during runtime in response to

	 * the host processing latency. Is this really worth it?

	 */

	htt->rx_ring.size = HTT_RX_RING_SIZE;

	htt->rx_ring.size_mask = htt->rx_ring.size - 1;

	htt->rx_ring.fill_level = HTT_RX_RING_FILL_LEVEL;



	if (!is_power_of_2(htt->rx_ring.size)) {

		ath10k_warn(ar, "htt rx ring size is not power of 2\n");

		return -EINVAL;

	}



	htt->rx_ring.size_mask = htt->rx_ring.size - 1;



	/*

	 * Set the initial value for the level to which the rx ring

	 * should be filled, based on the max throughput and the

	 * worst likely latency for the host to fill the rx ring

	 * with new buffers. In theory, this fill level can be

	 * dynamically adjusted from the initial value set here, to

	 * reflect the actual host latency rather than a

	 * conservative assumption about the host latency.

	 */

	htt->rx_ring.fill_level = ath10k_htt_rx_ring_fill_level(htt);



	htt->rx_ring.netbufs_ring =

		kzalloc(htt->rx_ring.size * sizeof(struct sk_buff *),

			GFP_KERNEL);