mt76: mt76x2e: disable pcie_aspm by default

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@natalenko.name>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

4 files changed, 51 insertions, 0 deletions

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@kernel.org>
+ */
+
+#include <linux/pci.h>
+
+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);