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Re: [PATCH v3 wireless-drivers 1/2] mt76: mt76x2e: disable pcie_aspm by default

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Hi.

On 27.10.2019 20:53, Lorenzo Bianconi wrote:
On same device (e.g. U7612E-H1) PCIE_ASPM causes continuous mcu hangs and instability. Since mt76x2 series does not manage PCIE PS states, first we
try to disable ASPM using pci_disable_link_state. If it fails, we will
disable PCIE PS configuring PCI registers.
This patch has been successfully tested on U7612E-H1 mini-pice card

Tested-by: Oleksandr Natalenko <oleksandr@xxxxxxxxxxxxxx>

For this revision, not yet ;) (see below).

Signed-off-by: Felix Fietkau <nbd@xxxxxxxx>
Signed-off-by: Lorenzo Bianconi <lorenzo@xxxxxxxxxx>
---
 drivers/net/wireless/mediatek/mt76/Makefile   |  2 +
 drivers/net/wireless/mediatek/mt76/mt76.h     |  1 +
 .../net/wireless/mediatek/mt76/mt76x2/pci.c   |  2 +
 drivers/net/wireless/mediatek/mt76/pci.c      | 46 +++++++++++++++++++
 4 files changed, 51 insertions(+)
 create mode 100644 drivers/net/wireless/mediatek/mt76/pci.c

diff --git a/drivers/net/wireless/mediatek/mt76/Makefile
b/drivers/net/wireless/mediatek/mt76/Makefile
index 4d03596e891f..d7a1ddc9e407 100644
--- a/drivers/net/wireless/mediatek/mt76/Makefile
+++ b/drivers/net/wireless/mediatek/mt76/Makefile
@@ -8,6 +8,8 @@ mt76-y := \
 	mmio.o util.o trace.o dma.o mac80211.o debugfs.o eeprom.o \
 	tx.o agg-rx.o mcu.o

+mt76-$(CONFIG_PCI) += pci.o
+
 mt76-usb-y := usb.o usb_trace.o

 CFLAGS_trace.o := -I$(src)
diff --git a/drivers/net/wireless/mediatek/mt76/mt76.h
b/drivers/net/wireless/mediatek/mt76/mt76.h
index 570c159515a0..dc468ed9434a 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76.h
+++ b/drivers/net/wireless/mediatek/mt76/mt76.h
@@ -578,6 +578,7 @@ bool __mt76_poll_msec(struct mt76_dev *dev, u32
offset, u32 mask, u32 val,
#define mt76_poll_msec(dev, ...) __mt76_poll_msec(&((dev)->mt76), __VA_ARGS__)

 void mt76_mmio_init(struct mt76_dev *dev, void __iomem *regs);
+void mt76_pci_disable_aspm(struct pci_dev *pdev);

 static inline u16 mt76_chip(struct mt76_dev *dev)
 {
diff --git a/drivers/net/wireless/mediatek/mt76/mt76x2/pci.c
b/drivers/net/wireless/mediatek/mt76/mt76x2/pci.c
index 73c3104f8858..cf611d1b817c 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76x2/pci.c
+++ b/drivers/net/wireless/mediatek/mt76/mt76x2/pci.c
@@ -81,6 +81,8 @@ mt76pci_probe(struct pci_dev *pdev, const struct
pci_device_id *id)
 	/* RG_SSUSB_CDR_BR_PE1D = 0x3 */
 	mt76_rmw_field(dev, 0x15c58, 0x3 << 6, 0x3);

+	mt76_pci_disable_aspm(pdev);
+
 	return 0;

 error:
diff --git a/drivers/net/wireless/mediatek/mt76/pci.c
b/drivers/net/wireless/mediatek/mt76/pci.c
new file mode 100644
index 000000000000..04c5a692bc85
--- /dev/null
+++ b/drivers/net/wireless/mediatek/mt76/pci.c
@@ -0,0 +1,46 @@
+// SPDX-License-Identifier: ISC
+/*
+ * Copyright (C) 2019 Lorenzo Bianconi <lorenzo@xxxxxxxxxx>
+ */
+
+#include <linux/pci.h>

FYI, I had to #include <linux/pci-aspm.h> on 5.3 kernel because this is where pci_disable_link_state() is defined. It is not needed on 5.4+ since the declaration got moved to pci.h; this is just a note for those who are going to test these changes on 5.3.

I'm still building the kernel, though. Will get back with the results later.

+
+void mt76_pci_disable_aspm(struct pci_dev *pdev)
+{
+	struct pci_dev *parent = pdev->bus->self;
+	u16 aspm_conf, parent_aspm_conf = 0;
+
+	pcie_capability_read_word(pdev, PCI_EXP_LNKCTL, &aspm_conf);
+	aspm_conf &= PCI_EXP_LNKCTL_ASPMC;
+	if (parent) {
+		pcie_capability_read_word(parent, PCI_EXP_LNKCTL,
+					  &parent_aspm_conf);
+		parent_aspm_conf &= PCI_EXP_LNKCTL_ASPMC;
+	}
+
+	if (!aspm_conf && (!parent || !parent_aspm_conf)) {
+		/* aspm already disabled */
+		return;
+	}
+
+	dev_info(&pdev->dev, "disabling ASPM %s %s\n",
+		 (aspm_conf & PCI_EXP_LNKCTL_ASPM_L0S) ? "L0s" : "",
+		 (aspm_conf & PCI_EXP_LNKCTL_ASPM_L1) ? "L1" : "");
+
+	if (IS_ENABLED(CONFIG_PCIEASPM)) {
+		int err;
+
+		err = pci_disable_link_state(pdev, aspm_conf);
+		if (!err)
+			return;
+	}
+
+	/* both device and parent should have the same ASPM setting.
+	 * disable ASPM in downstream component first and then upstream.
+	 */
+	pcie_capability_clear_word(pdev, PCI_EXP_LNKCTL, aspm_conf);
+	if (parent)
+		pcie_capability_clear_word(parent, PCI_EXP_LNKCTL,
+					   aspm_conf);
+}
+EXPORT_SYMBOL_GPL(mt76_pci_disable_aspm);

--
  Oleksandr Natalenko (post-factum)



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