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

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Date:   Thu, 26 Jan 2023 15:45:43 -0800
From:   Dan Williams <dan.j.williams@...el.com>
To:     Robert Richter <rrichter@....com>,
        Alison Schofield <alison.schofield@...el.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

Robert Richter wrote:
> On 23.01.23 11:26:55, Alison Schofield wrote:
> > 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.
> 
> Yes, that message is more meaningful.
> 

Applied with this fixup.