Hello Tim,
On 9/4/23 10:36, Tim Blechmann wrote:
> when we cannot get a tx buffer (`get_a_tx_buf`) `rpmsg_upref_sleepers`
> enables tx-complete interrupt.
> however if the interrupt is executed after `get_a_tx_buf` and before
> `rpmsg_upref_sleepers` we may mis the tx-complete interrupt and sleep
> for the full 15 seconds.
Is there any reason why your co-processor is unable to release the TX RPMSG
buffers for 15 seconds? If not, you should first determine the reason why it is
stalled.
Regards,
Arnaud
>
> in this case, so we re-try once before we really start to sleep
>
> Signed-off-by: Tim Blechmann <tim@xxxxxxxxxx>
> ---
> drivers/rpmsg/virtio_rpmsg_bus.c | 24 +++++++++++++++---------
> 1 file changed, 15 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c b/drivers/rpmsg/virtio_rpmsg_bus.c
> index 905ac7910c98..2a9d42225e60 100644
> --- a/drivers/rpmsg/virtio_rpmsg_bus.c
> +++ b/drivers/rpmsg/virtio_rpmsg_bus.c
> @@ -587,21 +587,27 @@ static int rpmsg_send_offchannel_raw(struct rpmsg_device *rpdev,
>
> /* no free buffer ? wait for one (but bail after 15 seconds) */
> while (!msg) {
> /* enable "tx-complete" interrupts, if not already enabled */
> rpmsg_upref_sleepers(vrp);
>
> - /*
> - * sleep until a free buffer is available or 15 secs elapse.
> - * the timeout period is not configurable because there's
> - * little point in asking drivers to specify that.
> - * if later this happens to be required, it'd be easy to add.
> - */
> - err = wait_event_interruptible_timeout(vrp->sendq,
> - (msg = get_a_tx_buf(vrp)),
> - msecs_to_jiffies(15000));
> + /* make sure to retry to grab tx buffer before we start waiting */
> + msg = get_a_tx_buf(vrp);
> + if (msg) {
> + err = 0;
> + } else {
> + /*
> + * sleep until a free buffer is available or 15 secs elapse.
> + * the timeout period is not configurable because there's
> + * little point in asking drivers to specify that.
> + * if later this happens to be required, it'd be easy to add.
> + */
> + err = wait_event_interruptible_timeout(vrp->sendq,
> + (msg = get_a_tx_buf(vrp)),
> + msecs_to_jiffies(15000));
> + }
>
> /* disable "tx-complete" interrupts if we're the last sleeper */
> rpmsg_downref_sleepers(vrp);
>
> /* timeout ? */
> if (!err) {
