linux-kernel - Re: [PATCH] Core driver for WM97xx touchscreens

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Date:	Fri, 18 Jan 2008 12:23:41 -0500
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
Cc:	linux-input@...ey.karlin.mff.cuni.cz, linux-kernel@...r.kernel.org,
	Liam Girdwood <liam.girdwood@...fsonmicro.com>,
	Graeme Gregory <gg@...nsource.wolfsonmicro.com>,
	Mike Arthur <mike.arthur@...fsonmicro.com>,
	Stanley Cai <stanley.cai@...el.com>,
	Rodolfo Giometti <giometti@...eenne.com>,
	Russell King <rmk@....linux.org.uk>,
	Marc Kleine-Budde <mkl@...gutronix.de>,
	Ian Molton <spyro@....com>,
	Vincent Sanders <vince@...likki.org>,
	Andrew Zabolotny <zap@...elink.ru>
Subject: Re: [PATCH] Core driver for WM97xx touchscreens

Hi Mark,

On Fri, Jan 18, 2008 at 04:27:06PM +0000, Mark Brown wrote:
> This patch series adds support for the touchscreen controllers provided
> by Wolfson Microelectronics WM97xx series chips in both polled and
> streaming modes.
>

Thank you for the patches. Some comments below.

> +static int wm97xx_ts_input_open(struct input_dev *idev)
> +{
> +	struct wm97xx *wm = (struct wm97xx *)input_get_drvdata(idev);

No need to cast.

> +
> +	mutex_lock(&wm->ts_mutex);
> +	/* first time opened ? */
> +	if (wm->ts_use_count++ == 0) {

You do not need to implement a counter here. Input core makes sure
that open and close are only called for the fist and last user
respectivly. ts_mutex can go away as well.

> +	/* set up touch configuration */
> +	wm->input_dev->name = "wm97xx touchscreen";
> +	wm->input_dev->open = wm97xx_ts_input_open;
> +	wm->input_dev->close = wm97xx_ts_input_close;
> +	set_bit(EV_ABS, wm->input_dev->evbit);
> +	set_bit(ABS_X, wm->input_dev->absbit);
> +	set_bit(ABS_Y, wm->input_dev->absbit);
> +	set_bit(ABS_PRESSURE, wm->input_dev->absbit);
> +	wm->input_dev->absmax[ABS_X] = abs_x[1];
> +	wm->input_dev->absmax[ABS_Y] = abs_y[1];
> +	wm->input_dev->absmax[ABS_PRESSURE] = abs_p[1];
> +	wm->input_dev->absmin[ABS_X] = abs_x[0];
> +	wm->input_dev->absmin[ABS_Y] = abs_y[0];
> +	wm->input_dev->absmin[ABS_PRESSURE] = abs_p[0];
> +	wm->input_dev->absfuzz[ABS_X] = abs_x[2];
> +	wm->input_dev->absfuzz[ABS_Y] = abs_y[2];
> +	wm->input_dev->absfuzz[ABS_PRESSURE] = abs_p[2];

input_set-abs_params(wm->input_dev, ABS_X, ...);
input_set-abs_params(wm->input_dev, ABS_Y, ...);
input_set-abs_params(wm->input_dev, ABS_X, ...);

I'd also recoomend using a temp for wm->input_dev, shoudl save a couple
of bytes.

> +	input_set_drvdata(wm->input_dev, wm);

Also wm->input_dev->dev.parent = &dev; to put it in the proper place
in sysfs hierarchy.

> +	ret = input_register_device(wm->input_dev);
> +	if (ret < 0) {

Add input_free_device(); here.

> +		kfree(wm);
> +		return -ENOMEM;
> +	}

I will need some more time to review and understand the need for the new bus
in the driver.

Thanks.

-- 
Dmitry
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