On Tue, Oct 7, 2025 at 10:19 AM 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 can help avoid false positive warning from mailbox > framework "Try increasing MBOX_TX_QUEUE_LEN". > > Signed-off-by: Tanmay Shah <[email protected]> > --- > > v2: > - Separate patch for remoteproc subsystem. > - Change design and introduce msg_slot_ro field for each channel > instead of API. Clients can use this variable directly. > - Remove mbox_queue_full API > > drivers/mailbox/mailbox.c | 3 +++ > include/linux/mailbox_controller.h | 2 ++ > 2 files changed, 5 insertions(+) > > diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c > index 5cd8ae222073..c2e187aa5d22 100644 > --- a/drivers/mailbox/mailbox.c > +++ b/drivers/mailbox/mailbox.c > @@ -35,6 +35,7 @@ static int add_to_rbuf(struct mbox_chan *chan, void *mssg) > idx = chan->msg_free; > chan->msg_data[idx] = mssg; > chan->msg_count++; > + chan->msg_slot_ro = (MBOX_TX_QUEUE_LEN - chan->msg_count); > > if (idx == MBOX_TX_QUEUE_LEN - 1) > chan->msg_free = 0; > @@ -70,6 +71,7 @@ static void msg_submit(struct mbox_chan *chan) > if (!err) { > chan->active_req = data; > chan->msg_count--; > + chan->msg_slot_ro = (MBOX_TX_QUEUE_LEN - > chan->msg_count); > No, I had suggested adding this info in client structure. There is no point in carrying msg_count and msg_slot_ro in mbox_chan. The client needs this info but can/should not access the chan internals.
thanks jassi
