linux-kernel - Re: [PATCH v1] HID: i2c-hid: use print_hex_dump

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Date:   Tue, 15 Aug 2023 14:02:40 +0800
From:   Riwen Lu <luriwen@...mail.com>
To:     Jiri Kosina <jikos@...nel.org>
Cc:     benjamin.tissoires@...hat.com, dmitry.torokhov@...il.com,
        linux@...ssschuh.net, hdegoede@...hat.com, rrangel@...omium.org,
        u.kleine-koenig@...gutronix.de, linux-input@...r.kernel.org,
        linux-kernel@...r.kernel.org, Riwen Lu <luriwen@...inos.cn>
Subject: Re: [PATCH v1] HID: i2c-hid: use print_hex_dump_debug to print report
 descriptor

在 2023/8/14 17:26, Jiri Kosina 写道:
> On Mon, 3 Jul 2023, Riwen Lu wrote:
> 
>> From: Riwen Lu <luriwen@...inos.cn>
>>
>> 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@...inos.cn>
>> ---
>>   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);
> 
> 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().