Hi Peng,
Thanks for reviews. Please find my comments below.
On 9/26/25 2:37 AM, Peng Fan wrote:
Hi Tanmay,
On Thu, Sep 25, 2025 at 11:50:44AM -0700, Tanmay Shah 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. This API can 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 | 24 ++++++++++++++++++++++++
drivers/remoteproc/xlnx_r5_remoteproc.c | 4 ++++
include/linux/mailbox_client.h | 1 +
The mailbox and remoteproc should be separated.
Mailbox framework is introducing new API. I wanted the use case to be in
the same patch-set, otherwise we might see unused API warning.
Hence, both in the same patch makes more sense. If maintainers prefer, I
will separate them.
3 files changed, 29 insertions(+)
diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c
index 5cd8ae222073..7afdb2c9006d 100644
--- a/drivers/mailbox/mailbox.c
+++ b/drivers/mailbox/mailbox.c
@@ -217,6 +217,30 @@ bool mbox_client_peek_data(struct mbox_chan *chan)
}
EXPORT_SYMBOL_GPL(mbox_client_peek_data);
+/**
+ * mbox_queue_full - check if mailbox queue is full or not
+ * @chan: Mailbox channel assigned to this client.
+ *
+ * Clients can choose not to send new msg if mbox queue is full.
+ *
+ * Return: true if queue is full else false. < 0 for error
+ */
+int mbox_queue_full(struct mbox_chan *chan)
+{
+ unsigned long flags;
+ int res;
+
+ if (!chan)
+ return -EINVAL;
+
+ spin_lock_irqsave(&chan->lock, flags);
Use scoped_guard.
Other APIs use spin_lock_irqsave. Probably scoped_guard should be
introduced in a different patch for all APIs in the mailbox.
+ res = (chan->msg_count == (MBOX_TX_QUEUE_LEN - 1));
+ spin_unlock_irqrestore(&chan->lock, flags);
+
+ return res;
+}
+EXPORT_SYMBOL_GPL(mbox_queue_full);
add_to_rbuf is able to return ENOBUFS when call mbox_send_message.
Does checking mbox_send_message return value works for you?
That is the problem. mbox_send_message uses add_to_rbuf and fails. But
during failure, it prints warning message:
dev_err(chan->mbox->dev, "Try increasing MBOX_TX_QUEUE_LEN\n");
In some cases there are lot of such messages on terminal. Functionally
nothing is wrong and everything is working but user keeps getting false
positive warning about increasing mbox tx queue length. That is why we
need API to check if mbox queue length is full or not before doing
mbox_send_message. Not all clients need to use it, but some cane make
use of it.
+
/**
* mbox_send_message - For client to submit a message to be
* sent to the remote.
Regards
Peng
