Hi Jassi, Thank You for reviews.
I agree to all your comments, and I will address them in the next revision. I am returning from the leave now hence delay in the response. Tanmay On 1/18/2026 1:53 PM, Jassi Brar wrote: > On Wed, Dec 17, 2025 at 3:27 PM Tanmay Shah <[email protected]> wrote: >> >> Sometimes clients need to know if mailbox queue is full or not before >> posting new message via mailbox. If mailbox queue is full clients can >> choose not to post new message. This doesn't mean current queue length >> should be increased, but clients may want to wait till previous Tx is >> done. Introduce variable per channel to track available msg slots. >> Clients can check this variable and decide not to send new message if >> it is 0. This will help avoid false positive warning from mailbox >> framework "Try increasing MBOX_TX_QUEUE_LEN". >> >> Signed-off-by: Tanmay Shah <[email protected]> >> --- >> drivers/mailbox/mailbox.c | 3 +++ >> include/linux/mailbox_client.h | 2 ++ >> 2 files changed, 5 insertions(+) >> >> diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c >> index 2acc6ec229a4..b7ae5c173143 100644 >> --- a/drivers/mailbox/mailbox.c >> +++ b/drivers/mailbox/mailbox.c >> @@ -36,6 +36,7 @@ static int add_to_rbuf(struct mbox_chan *chan, void *mssg) >> idx = chan->msg_free; >> chan->msg_data[idx] = mssg; >> chan->msg_count++; >> + chan->cl->msg_slot_ro = (MBOX_TX_QUEUE_LEN - chan->msg_count); >> > msg_count is protected by a lock and limited within MBOX_TX_QUEUE_LEN, > so how about simply chan->cl->msg_slot_ro--; > >> if (idx == MBOX_TX_QUEUE_LEN - 1) >> chan->msg_free = 0; >> @@ -71,6 +72,7 @@ static void msg_submit(struct mbox_chan *chan) >> if (!err) { >> chan->active_req = data; >> chan->msg_count--; >> + chan->cl->msg_slot_ro = (MBOX_TX_QUEUE_LEN - >> chan->msg_count); >> > Similarly chan->cl->msg_slot_ro++ ? > >> } >> } >> >> @@ -321,6 +323,7 @@ static int __mbox_bind_client(struct mbox_chan *chan, >> struct mbox_client *cl) >> chan->msg_count = 0; >> chan->active_req = NULL; >> chan->cl = cl; >> + chan->cl->msg_slot_ro = MBOX_TX_QUEUE_LEN; >> init_completion(&chan->tx_complete); >> >> if (chan->txdone_method == TXDONE_BY_POLL && >> cl->knows_txdone) >> diff --git a/include/linux/mailbox_client.h b/include/linux/mailbox_client.h >> index c6eea9afb943..a073fb0c03d1 100644 >> --- a/include/linux/mailbox_client.h >> +++ b/include/linux/mailbox_client.h >> @@ -17,6 +17,7 @@ struct mbox_chan; >> * @dev: The client device >> * @tx_block: If the mbox_send_message should block until data is >> * transmitted. >> + * @msg_slot_ro: msg slots remaining for this client's channel. >> * @tx_tout: Max block period in ms before TX is assumed failure >> * @knows_txdone: If the client could run the TX state machine. Usually >> * if the client receives some ACK packet for >> transmission. >> @@ -29,6 +30,7 @@ struct mbox_chan; >> struct mbox_client { >> struct device *dev; >> bool tx_block; >> + unsigned int msg_slot_ro; >> > maybe call it 'tx_slots_available_ro' ? > > Thanks
