Re: [PATCH v3 12/13] wifi: mt76: mt7925: disable ASPM and runtime PM for MT7927

[Sean Wang <sean.wang@kernel.org>]

Hi, Javier

On Wed, Mar 25, 2026 at 5:13 PM Javier Tia <floss@jetm.me> wrote:
>
> Disable PCIe ASPM unconditionally for MT7927. The CONNINFRA power
> domain and WFDMA register access are unreliable with PCIe L1 active,
> causing throughput to drop from 1+ Gbps to ~200 Mbps.
>
> Disable runtime PM and deep sleep for MT7927. The combo chip shares
> a CONNINFRA power domain between WiFi (PCIe) and BT (USB).
> SET_OWN/CLR_OWN transitions on the LPCTL register crash the BT
> firmware, requiring a full power cycle to recover. PM enablement will
> be addressed in a follow-up once safe power state transitions are
> determined.
>
> Signed-off-by: Javier Tia <floss@jetm.me>
> ---
>  drivers/net/wireless/mediatek/mt76/mt7925/init.c | 6 +++++-
>  drivers/net/wireless/mediatek/mt76/mt7925/pci.c  | 9 +++++++--
>  2 files changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/wireless/mediatek/mt76/mt7925/init.c b/drivers/net/wireless/mediatek/mt76/mt7925/init.c
> index c4c99380f5b5..89140fc6a2b6 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt7925/init.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt7925/init.c
> @@ -243,7 +243,11 @@ int mt7925_register_device(struct mt792x_dev *dev)
>         dev->pm.idle_timeout = MT792x_PM_TIMEOUT;
>         dev->pm.stats.last_wake_event = jiffies;
>         dev->pm.stats.last_doze_event = jiffies;
> -       if (!mt76_is_usb(&dev->mt76)) {
> +       /* MT7927: runtime PM disabled. The combo chip shares a CONNINFRA
> +        * power domain between WiFi (PCIe) and BT (USB). SET_OWN/CLR_OWN
> +        * transitions on the LPCTL register crash BT firmware.
> +        */

I think this level of detail is better kept in the commit message. For
the code itself, a short comment should be enough, or even no comment
if the condition is already clear enough.

> +       if (!mt76_is_usb(&dev->mt76) && !is_mt7927(&dev->mt76)) {
>                 dev->pm.enable_user = true;
>                 dev->pm.enable = true;
>                 dev->pm.ds_enable_user = true;
> diff --git a/drivers/net/wireless/mediatek/mt76/mt7925/pci.c b/drivers/net/wireless/mediatek/mt76/mt7925/pci.c
> index 393d9f408b84..693e08f35d68 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt7925/pci.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt7925/pci.c
> @@ -530,7 +530,13 @@ static int mt7925_pci_probe(struct pci_dev *pdev,
>         if (ret)
>                 goto err_free_pci_vec;
>
> -       if (mt7925_disable_aspm)
> +       is_mt7927_hw = (pdev->device == 0x6639 || pdev->device == 0x7927);
> +
> +       /* MT7927: CONNINFRA power domain and WFDMA register access are
> +        * unreliable with PCIe L1 active, causing throughput to drop
> +        * from 1+ Gbps to ~200 Mbps. Disable ASPM unconditionally.
> +        */

Ditto

> +       if (mt7925_disable_aspm || is_mt7927_hw)
>                 mt76_pci_disable_aspm(pdev);
>
>         ops = mt792x_get_mac80211_ops(&pdev->dev, &mt7925_ops,
> @@ -562,7 +568,6 @@ static int mt7925_pci_probe(struct pci_dev *pdev,
>         dev = container_of(mdev, struct mt792x_dev, mt76);
>         dev->fw_features = features;
>         dev->hif_ops = &mt7925_pcie_ops;
> -       is_mt7927_hw = (pdev->device == 0x6639 || pdev->device == 0x7927);
>         dev->irq_map = is_mt7927_hw ? &mt7927_irq_map : &irq_map;
>         dev->dma_config = is_mt7927_hw ? &mt7927_dma_cfg : &mt7925_dma_cfg;
>         mt76_mmio_init(&dev->mt76, pcim_iomap_table(pdev)[0]);
>
> --
> 2.53.0
>
>