Re: [PATCH v1] HID: i2c-hid: use print_hex_dump_debug to print report descriptor

[Riwen Lu]

在 2023/8/15 14:35, Rahul Rameshbabu 写道:
> On Tue, 15 Aug, 2023 14:02:40 +0800 "Riwen Lu" <luriwen@xxxxxxxxxxx> wrote:
> > 在 2023/8/14 17:26, Jiri Kosina 写道:
> > > On Mon, 3 Jul 2023, Riwen Lu wrote:
> > >
> > > > From: Riwen Lu <luriwen@xxxxxxxxxx>
> > > >
> > > > The format '%*ph' print up to 64 bytes long as a hex string with ' '
> > > > sepatator. Usually the size of report descriptor is larger than 64
> > > > bytes, so consider using print_hex_dump_debug to print out all of it for
> > > > better debugging.
> > > >
> > > > Signed-off-by: Riwen Lu <luriwen@xxxxxxxxxx>
> > > > ---
> > > >    drivers/hid/i2c-hid/i2c-hid-core.c | 4 +++-
> > > >    1 file changed, 3 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/hid/i2c-hid/i2c-hid-core.c b/drivers/hid/i2c-hid/i2c-hid-core.c
> > > > index efbba0465eef..8e97fc01c852 100644
> > > > --- a/drivers/hid/i2c-hid/i2c-hid-core.c
> > > > +++ b/drivers/hid/i2c-hid/i2c-hid-core.c
> > > > @@ -772,7 +772,9 @@ static int i2c_hid_parse(struct hid_device *hid)
> > > >    		}
> > > >    	}
> > > >
> > > > -	i2c_hid_dbg(ihid, "Report Descriptor: %*ph\n", rsize, rdesc);
> > > > +	i2c_hid_dbg(ihid, "Report Descriptor\n");
> > > > +	print_hex_dump_debug("  ", DUMP_PREFIX_OFFSET, 16, 1,
> > > > +			rdesc, rsize, false);
>
> Maybe it makes sense to use a prefix for the hex dump that is easy to
> trace rather than padding whitespace? This looks good when you do not
> see any other kernel message log lines get interlaced when written.
> However, if you have a lot of concurrent kernel message output, I think
> it can be tough to piece together the lines of the dump with this
> prefix. Just my opinion.
That's a good opinion. I'll make a v2 version.

Thanks.
> > > But that would dump it unconditionally, while i2c_hid_dbg() is
> > > conditional.
> > Function print_hex_dump_debug() dump messages is as conditional as
> > i2c_hid_dbg().
> >
> > The function i2c_hid_dbg() defines as follows:
> > #define i2c_hid_dbg(ihid, ...) dev_dbg(&(ihid)->client->dev, __VA_ARGS__)
> >
> > dev_dbg() depends on the same macro as print_hex_dump_debug().
>
> I agree with this point. Both dev_dbg and print_hex_dump_debug are noops
> if neither CONFIG_DYNAMIC_DEBUG is set or DEBUG is defined.
>
> --
> Thanks,
>
> Rahul Rameshbabu