linux-kernel - Re: [PATCH] cxl/mbox: Add debug messages for supported mailbox commands

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Date:   Mon, 23 Jan 2023 11:26:55 -0800
From:   Alison Schofield <alison.schofield@...el.com>
To:     Robert Richter <rrichter@....com>
Cc:     Vishal Verma <vishal.l.verma@...el.com>,
        Ira Weiny <ira.weiny@...el.com>,
        Ben Widawsky <bwidawsk@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Jonathan Cameron <jonathan.cameron@...wei.com>,
        linux-cxl@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] cxl/mbox: Add debug messages for supported mailbox
 commands

On Mon, Jan 23, 2023 at 01:32:55PM +0100, Robert Richter wrote:
> Hi Alison,
> 
> On 22.01.23 21:39:33, Alison Schofield wrote:
> > On Thu, Jan 19, 2023 at 02:04:50PM +0100, Robert Richter wrote:
> > > Only unsupported mailbox commands are reported in debug messages. A
> > > list of supported commands is useful too. Change debug messages to
> > > also report the opcodes of supported commands.
> > 
> > Hi Robert,
> > I wonder if you can get this info another way. When I try this 
> > loading cxl_test today, I get 99 new messages. Is this going to
> > create too much noise with debug kernels?
> 
> There are 26 commands supported by the driver, so I assume there are
> at least 4 cards in your system? To me the number of messages looks ok
> for a debug kernel. And, most kernels have dyndbg enabled allowing to
> enable only messages of interest? Esp. if card initialization fails
> there is no way to get this information from userland. The list of
> unsupported commands is of less use than the one for supported. That
> is the intention for the change.

cxl_walk_cel() job is to create the enabled_cmds list for the device.
How about we use that language in the message, like:

		set_bit(cmd->info.id, cxlds->enabled_cmds);
-               dev_dbg(cxlds->dev, "Opcode 0x%04x supported by driver\n", opcode);
+               dev_dbg(cxlds->dev, "Opcode 0x%04x enabled\n", opcode);

Because when we say, "Opcode 0x%04x supported by driver\n", that comes
with the assumption that the device supported it too. By saying
'enabled', it's clear device and driver are aligned.

> 
> Thanks,
> 
> -Robert