Re: [RFC PATCH 6/9] net: dsa: hellcreek: Add debugging mechanisms

Hi Andrew,

On Thu Jun 18 2020, Andrew Lunn wrote:

On Thu, Jun 18, 2020 at 08:40:26AM +0200, Kurt Kanzenbach wrote:

quoted

The switch has registers which are useful for debugging issues:

debugfs is not particularly likes. Please try to find other means
where possible. Memory usage fits nicely into devlink. See mv88e6xxx
which exports the ATU fill for example.

OK, I'll have a look at devlink and the mv88e6xxx driver to see if that
could be utilized.

Are trace registers counters?

No. The trace registers provide bits for error conditions and if packets
have been dropped e.g. because of full queues or FCS errors, and so on.

quoted

+static int hellcreek_debugfs_init(struct hellcreek *hellcreek)
+{
+	struct dentry *file;
+
+	hellcreek->debug_dir = debugfs_create_dir(dev_name(hellcreek->dev),
+						  NULL);
+	if (!hellcreek->debug_dir)
+		return -ENOMEM;

Just a general comment. You should not check the return value from any
debugfs call, since it is totally optional. It will also do the right
thing if the previous call has failed. There are numerous emails from
GregKH about this.

OK.

Thanks,
Kurt