[PATCH] wifi: mt76: mt792x: fix firmware reload failure after previous load crash

[Sean Wang]

On Fri, Jan 2, 2026 at 2:03 PM Zac Bowling <zbowling at gmail.com> wrote:
>
> If the firmware loading process crashes or is interrupted after
> acquiring the patch semaphore but before releasing it, subsequent
> firmware load attempts will fail with 'Failed to get patch semaphore'
> because the semaphore is still held.
>
> This issue manifests as devices becoming unusable after suspend/resume
> failures or firmware crashes, requiring a full hardware reboot to
> recover. This has been widely reported on MT7921 and MT7925 devices.
>
> Apply the same fix that was applied to MT7915 in commit 79dd14f:
> 1. Release the patch semaphore before starting firmware load (in case
>    it was held by a previous failed attempt)
> 2. Restart MCU firmware to ensure clean state
> 3. Wait briefly for MCU to be ready
>
> This fix applies to both MT7921 and MT7925 drivers which share the
> mt792x_load_firmware() function.
>
> Fixes: 'Failed to get patch semaphore' errors after firmware crash
> Signed-off-by: Zac Bowling <zac at zacbowling.com>
> ---
>  mt792x_core.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
>
> diff --git a/mt792x_core.c b/mt792x_core.c
> index cc488ee9..b82e4470 100644
> --- a/mt792x_core.c
> +++ b/mt792x_core.c
> @@ -927,6 +927,20 @@ int mt792x_load_firmware(struct mt792x_dev *dev)
>  {
>         int ret;
>
> +       /* Release semaphore if taken by previous failed load attempt.
> +        * This prevents "Failed to get patch semaphore" errors when
> +        * recovering from firmware crashes or suspend/resume failures.
> +        */
> +       ret = mt76_connac_mcu_patch_sem_ctrl(&dev->mt76, false);
> +       if (ret < 0)
> +               dev_dbg(dev->mt76.dev, "Semaphore release returned %d (may be expected)\n", ret);
> +
> +       /* Always restart MCU to ensure clean state before loading firmware */
> +       mt76_connac_mcu_restart(&dev->mt76);
> +
> +       /* Wait for MCU to be ready after restart */
> +       msleep(100);
> +

Hi Zac,

This is a good finding. Since this is a common mt792x code path, have you
also had a chance to test it on MT7921?

One small nit: the Fixes tag should reference the actual commit being
fixed, e.g.

  Fixes: <commit-sha> ("mt76: mt792x: ...")

instead of the error string.

                  Sean

>         ret = mt76_connac2_load_patch(&dev->mt76, mt792x_patch_name(dev));
>         if (ret)
>                 return ret;
> --
> 2.51.0
>
>
>