"tegra-hsp b950000.tegra-hsp: Try increasing MBOX_TX_QUEUE_LEN" on AGX Orin, Jetpack 6.0GA

[gdwang]

Hi,
We found that some error messages like “tegra-hsp b950000.tegra-hsp: Try increasing MBOX_TX_QUEUE_LEN” reported on Orin booting.
What is the cause of this error, and will it have any impact on usage?

[gdwang]

In source code “kernel/kernel-jammy-src/include/linux/mailbox_controller.h”, it says:

/*
 * The length of circular buffer for queuing messages from a client.
 * 'msg_count' tracks the number of buffered messages while 'msg_free'
 * is the index where the next message would be buffered.
 * We shouldn't need it too big because every transfer is interrupt
 * triggered and if we have lots of data to transfer, the interrupt
 * latencies are going to be the bottleneck, not the buffer length.
 * Besides, mbox_send_message could be called from atomic context and
 * the client could also queue another message from the notifier 'tx_done'
 * of the last transfer done.
 * REVISIT: If too many platforms see the "Try increasing MBOX_TX_QUEUE_LEN"
 * print, it needs to be taken from config option or somesuch.
 */
#define MBOX_TX_QUEUE_LEN       20

Do you think it’s necessary to change MBOX_TX_QUEUE_LEN value?

[kayccc]

Are you using devkit or with custom carrier board?
Which JetPack SW?

Does this cause anything go wrong there?

[gdwang]

We are using our own carrier board, and the JetPack version is 6.0GA.
Nothing seems wrong so far, but we are concerned about potential risks.