linux-kernel - Re: [PATCH v2 29/49] Input: atmel_mxt_ts - implement debug output for messages

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Message-ID: <20190829153124.cozqsegnmvxveecd@holly.lan>
Date:   Thu, 29 Aug 2019 16:31:24 +0100
From:   Daniel Thompson <daniel.thompson@...aro.org>
To:     Jiada Wang <jiada_wang@...tor.com>
Cc:     nick@...anahar.org, dmitry.torokhov@...il.com,
        linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
        george_davis@...tor.com
Subject: Re: [PATCH v2 29/49] Input: atmel_mxt_ts - implement debug output
 for messages

On Tue, Aug 27, 2019 at 03:29:23PM +0900, Jiada Wang wrote:
> From: Nick Dyer <nick.dyer@...ev.co.uk>
> 
> Add a debug switch which causes all messages from the touch controller to
> be dumped to the dmesg log with a set prefix "MXT MSG:". This is used by
> Atmel user-space utilities to debug touch operation. Enabling this output
> does impact touch performance.
> 
> Signed-off-by: Nick Dyer <nick.dyer@...ev.co.uk>
> (cherry picked from ndyer/linux/for-upstream commit 3c3fcfdd4889dfeb1c80ae8cd94a622c6342b06a)
> [gdavis: Forward port and fix conflicts.]
> Signed-off-by: George G. Davis <george_davis@...tor.com>
> Signed-off-by: Jiada Wang <jiada_wang@...tor.com>
> ---
>  drivers/input/touchscreen/atmel_mxt_ts.c | 44 ++++++++++++++++++++++--
>  1 file changed, 41 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
> index 2d2e8ea30547..941c6970cb70 100644
> --- a/drivers/input/touchscreen/atmel_mxt_ts.c
> +++ b/drivers/input/touchscreen/atmel_mxt_ts.c
> @@ -335,6 +335,7 @@ struct mxt_data {
>  	u8 t100_aux_ampl;
>  	u8 t100_aux_area;
>  	u8 t100_aux_vect;
> +	bool debug_enabled;
>  	u8 max_reportid;
>  	u32 config_crc;
>  	u32 info_crc;
> @@ -460,8 +461,8 @@ static bool mxt_object_readable(unsigned int type)
>  
>  static void mxt_dump_message(struct mxt_data *data, u8 *message)
>  {
> -	dev_dbg(&data->client->dev, "message: %*ph\n",
> -		data->T5_msg_size, message);
> +	dev_dbg(&data->client->dev, "MXT MSG: %*ph\n",
> +		       data->T5_msg_size, message);

I'm not 100% convinced that the kernel should change here (arguably the
userspace utility should be modified instead) but if the messages are
conforming to some sort of vendor specific protocol then some commenting
is needed.


> @@ -3538,6 +3573,8 @@ static DEVICE_ATTR(hw_version, S_IRUGO, mxt_hw_version_show, NULL);
>  static DEVICE_ATTR(object, S_IRUGO, mxt_object_show, NULL);
>  static DEVICE_ATTR(update_cfg, S_IWUSR, NULL, mxt_update_cfg_store);
>  static DEVICE_ATTR(config_crc, S_IRUGO, mxt_config_crc_show, NULL);
> +static DEVICE_ATTR(debug_enable, S_IWUSR | S_IRUSR, mxt_debug_enable_show,
> +		   mxt_debug_enable_store);

Why isn't CONFIG_DYNAMIC_DEBUG sufficient to enable/disable the
messages?


Daniel.