Re: [PATCH V3 04/16] i3c: mipi-i3c-hci: Wait for DMA ring restart to complete

On Mon, May 04, 2026 at 02:33:40PM +0300, Adrian Hunter wrote:
> Although hci_dma_dequeue_xfer() is serialized against itself via
> control_mutex, this does not guarantee that a DMA ring restart
> triggered by a previous invocation has fully completed.
>
> When the function is called again in rapid succession, the DMA ring may
> still be transitioning back to the running state, which may confound or
> disrupt further state changes.
>
> Address this by waiting for the DMA ring restart to complete before
> continuing.
>
> Signed-off-by: Adrian Hunter <[email protected]>
> ---

Reviewed-by: Frank Li <[email protected]>

>
>
> Changes in V2 and V3:
>
> 	None
>
>
>  drivers/i3c/master/mipi-i3c-hci/dma.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/i3c/master/mipi-i3c-hci/dma.c b/drivers/i3c/master/mipi-i3c-hci/dma.c
> index 314635e6e190..28614fdbf558 100644
> --- a/drivers/i3c/master/mipi-i3c-hci/dma.c
> +++ b/drivers/i3c/master/mipi-i3c-hci/dma.c
> @@ -617,6 +617,7 @@ static bool hci_dma_dequeue_xfer(struct i3c_hci *hci,
>  	}
>
>  	/* restart the ring */
> +	reinit_completion(&rh->op_done);
>  	mipi_i3c_hci_resume(hci);
>  	rh_reg_write(RING_CONTROL, RING_CTRL_ENABLE);
>  	rh_reg_write(RING_CONTROL, RING_CTRL_ENABLE | RING_CTRL_RUN_STOP);
> @@ -625,6 +626,8 @@ static bool hci_dma_dequeue_xfer(struct i3c_hci *hci,
>
>  	spin_unlock_irq(&hci->lock);
>
> +	wait_for_completion_timeout(&rh->op_done, HZ);
> +
>  	return did_unqueue;
>  }
>
> --
> 2.51.0
>

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