Re: [PATCH rtw-next v9 0/4] wifi: rtw88: sdio: Fix unhandled RX request interrupt storm

["Luka Gejak" <luka.gejak@linux.dev>]

November 7, 2026 at 4:53 AM, "Alastair D'Silva" <alastair@d-silva.org> wrote:

> 
> On 3081-based SDIO chips (observed on RTL8821CS; RTL8822BS and RTL8822CS
> are inferred to be affected as they share the 3081 architecture), clearing
> REG_SDIO_HISR_RX_REQUEST requires both a software W1C acknowledge and an
> empty RX FIFO. Masking this bit out before writing back to HISR prevents
> the software acknowledge from happening, leaving the bit asserted even
> after the FIFO is drained and trapping the CPU core in an infinite
> interrupt storm that locks up the system upon receiving network traffic.
> 
> This series fixes the interrupt storm on 3081 chips and addresses
> related SDIO lifecycle, locking, and error handling issues:
> 
> - Patch 1 returns error codes from rtw_sdio_rxfifo_recv() on allocation,
>  oversized packet, or read failures so the caller stops immediately
>  instead of burning through the loop budget.
> - Patch 2 tracks operational state via rtwsdio->running protected by an
>  irq_lock mutex (using a mutex as SDIO bus operations sleep), serializes
>  start/stop state transitions under sdio_claim_host() and irq_lock,
>  cancels the TX worker synchronously on stop, drains rtwsdio->tx_queue[]
>  with locked skb_dequeue() and ieee80211_free_txskb() in rtw_sdio_stop()
>  and again in rtw_sdio_start(), and resets rtwsdio->tx_queue_stopped[]
>  while waking stopped AC queues under tx_queue[].lock in rtw_sdio_start().
> - Patch 3 fixes the interrupt storm by splitting
>  rtw_sdio_handle_interrupt() into 8051 and 3081 paths. On 3081,
>  interrupts are masked via HIMR, acknowledged via W1C writeback,
>  serviced, and re-enabled under irq_lock if still running.
> - Patch 4 refactors rtw_sdio_rx_isr() into separate 8051 and 3081 variants
>  to clarify the differences in register width and HISR handling without
>  any logic changes.
> 

Thanks for addressing those comments, v9 looks good to me,

Reviewed-by: Luka Gejak <luka.gejak@linux.dev>

Best regards,
Luka Gejak