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Revision b76889ff51bfee318bea15891420e5aefd2833a0 authored by Yannick Vignon on 13 January 2021, 13:15:56 UTC, committed by Jakub Kicinski on 14 January 2021, 18:49:42 UTC 
net: stmmac: fix taprio schedule configuration
 
When configuring a 802.1Qbv schedule through the tc taprio qdisc on an NXP
i.MX8MPlus device, the effective cycle time differed from the requested one
by N*96ns, with N number of entries in the Qbv Gate Control List. This is
because the driver was adding a 96ns margin to each interval of the GCL,
apparently to account for the IPG. The problem was observed on NXP
i.MX8MPlus devices but likely affected all devices relying on the same
configuration callback (dwmac 4.00, 4.10, 5.10 variants).

Fix the issue by removing the margins, and simply setup the MAC with the
provided cycle time value. This is the behavior expected by the user-space
API, as altering the Qbv schedule timings would break standards conformance.
This is also the behavior of several other Ethernet MAC implementations
supporting taprio, including the dwxgmac variant of stmmac.

Fixes: 504723af0d85 ("net: stmmac: Add basic EST support for GMAC5+")
Signed-off-by: Yannick Vignon <yannick.vignon@nxp.com>
Link: https://lore.kernel.org/r/20210113131557.24651-1-yannick.vignon@oss.nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
1 parent 2576477
Raw File
shuffle.h 
// SPDX-License-Identifier: GPL-2.0
// Copyright(c) 2018 Intel Corporation. All rights reserved.
#ifndef _MM_SHUFFLE_H
#define _MM_SHUFFLE_H
#include <linux/jump_label.h>

#define SHUFFLE_ORDER (MAX_ORDER-1)

#ifdef CONFIG_SHUFFLE_PAGE_ALLOCATOR
DECLARE_STATIC_KEY_FALSE(page_alloc_shuffle_key);
extern void __shuffle_free_memory(pg_data_t *pgdat);
extern bool shuffle_pick_tail(void);
static inline void shuffle_free_memory(pg_data_t *pgdat)
{
	if (!static_branch_unlikely(&page_alloc_shuffle_key))
		return;
	__shuffle_free_memory(pgdat);
}

extern void __shuffle_zone(struct zone *z);
static inline void shuffle_zone(struct zone *z)
{
	if (!static_branch_unlikely(&page_alloc_shuffle_key))
		return;
	__shuffle_zone(z);
}

static inline bool is_shuffle_order(int order)
{
	if (!static_branch_unlikely(&page_alloc_shuffle_key))
		return false;
	return order >= SHUFFLE_ORDER;
}
#else
static inline bool shuffle_pick_tail(void)
{
	return false;
}

static inline void shuffle_free_memory(pg_data_t *pgdat)
{
}

static inline void shuffle_zone(struct zone *z)
{
}

static inline bool is_shuffle_order(int order)
{
	return false;
}
#endif
#endif /* _MM_SHUFFLE_H */
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