mt76: mt76_vif_phy() return hw->priv when chanctx is absent

[EdinsonMoreno]

Problem

On single-radio setups or during early STA association events, mlink->ctx may not be assigned yet. mt76_vif_phy() currently returns NULL in this case, which propagates as -EINVAL (-22) to any caller that doesn't explicitly guard against NULL, causing station insertion to fail:

wlp3s0: failed to insert STA entry for the AP (error -22)

Reported by @oswystk15662 in issue #11: #11 (comment)

Fix

Return hw->priv (the primary PHY) instead of NULL when mlink->ctx == NULL. This matches the behavior already implemented for kernels >= 6.15 with !hw->wiphy->n_radio:

#if (LINUX_VERSION_CODE >= KERNEL_VERSION(6, 15, 0))
    if (!hw->wiphy->n_radio)
        return hw->priv;
#endif

The same logic applies here: on a single-radio device with no chanctx assigned yet, hw->priv is always the correct PHY to return.

Tested on

• Hardware: MT7902 (PCI 14c3:7902)
• Kernel: 7.0.9 (Fedora 44)
• WiFi association completes successfully after this fix

Note

This fix was verified independently by @oswystk15662 (Ubuntu 22.04, kernel 6.8.0) as resolving the -22 error on their setup.

[Erwin-Iosef]

Thanks for the work, but if this isn't for a specific version of the kernel if I understand it right, shouldn't this be submitted upstream as well?