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23 October 2021, 00:29:24 UTC
Revision 275e88b06a277ccf89d9c471a777e9b4f8c552b0 authored by Rob Herring on 18 December 2020, 14:39:05 UTC, committed by Bjorn Helgaas on 26 December 2020, 03:58:36 UTC 
PCI: tegra: Fix host link initialization
 
Commit b9ac0f9dc8ea ("PCI: dwc: Move dw_pcie_setup_rc() to DWC common
code") broke enumeration of downstream devices on Tegra:

In non-working case (next-20201211):

  0001:00:00.0 PCI bridge: NVIDIA Corporation Device 1ad2 (rev a1)
  0001:01:00.0 SATA controller: Marvell Technology Group Ltd. Device 9171 (rev 13)
  0005:00:00.0 PCI bridge: NVIDIA Corporation Device 1ad0 (rev a1)

In working case (v5.10-rc7):

  0001:00:00.0 PCI bridge: Molex Incorporated Device 1ad2 (rev a1)
  0001:01:00.0 SATA controller: Marvell Technology Group Ltd. Device 9171 (rev 13)
  0005:00:00.0 PCI bridge: Molex Incorporated Device 1ad0 (rev a1)
  0005:01:00.0 PCI bridge: PLX Technology, Inc. Device 3380 (rev ab)
  0005:02:02.0 PCI bridge: PLX Technology, Inc. Device 3380 (rev ab)
  0005:03:00.0 USB controller: PLX Technology, Inc. Device 3380 (rev ab)

The problem seems to be dw_pcie_setup_rc() is now called twice before and
after the link up handling. The fix is to move Tegra's link up handling to
.start_link() function like other DWC drivers. Tegra is a bit more
complicated than others as it re-inits the whole DWC controller to retry
the link. With this, the initialization ordering is restored to match the
prior sequence.

Fixes: b9ac0f9dc8ea ("PCI: dwc: Move dw_pcie_setup_rc() to DWC common code")
Link: https://lore.kernel.org/r/20201218143905.1614098-1-robh@kernel.org
Reported-by: Mian Yousaf Kaukab <ykaukab@suse.de>
Tested-by: Mian Yousaf Kaukab <ykaukab@suse.de>
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Jonathan Hunter <jonathanh@nvidia.com>
Cc: Vidya Sagar <vidyas@nvidia.com>
1 parent 255b2d5
Raw File
Tip revision: 275e88b06a277ccf89d9c471a777e9b4f8c552b0 authored by Rob Herring on 18 December 2020, 14:39:05 UTC
PCI: tegra: Fix host link initialization
Tip revision: 275e88b
governor_performance.c 
// SPDX-License-Identifier: GPL-2.0-only
/*
 *  linux/drivers/devfreq/governor_performance.c
 *
 *  Copyright (C) 2011 Samsung Electronics
 *	MyungJoo Ham <myungjoo.ham@samsung.com>
 */

#include <linux/devfreq.h>
#include <linux/module.h>
#include "governor.h"

static int devfreq_performance_func(struct devfreq *df,
				    unsigned long *freq)
{
	/*
	 * target callback should be able to get floor value as
	 * said in devfreq.h
	 */
	*freq = DEVFREQ_MAX_FREQ;
	return 0;
}

static int devfreq_performance_handler(struct devfreq *devfreq,
				unsigned int event, void *data)
{
	int ret = 0;

	if (event == DEVFREQ_GOV_START) {
		mutex_lock(&devfreq->lock);
		ret = update_devfreq(devfreq);
		mutex_unlock(&devfreq->lock);
	}

	return ret;
}

static struct devfreq_governor devfreq_performance = {
	.name = DEVFREQ_GOV_PERFORMANCE,
	.get_target_freq = devfreq_performance_func,
	.event_handler = devfreq_performance_handler,
};

static int __init devfreq_performance_init(void)
{
	return devfreq_add_governor(&devfreq_performance);
}
subsys_initcall(devfreq_performance_init);

static void __exit devfreq_performance_exit(void)
{
	int ret;

	ret = devfreq_remove_governor(&devfreq_performance);
	if (ret)
		pr_err("%s: failed remove governor %d\n", __func__, ret);

	return;
}
module_exit(devfreq_performance_exit);
MODULE_LICENSE("GPL");
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