linux-kernel - Re: [PATCH v4 2/2] Input: add MStar MSG2638 touchscreen driver

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Message-ID: <a22fda89b5f97418e936655817f45bd55f6248ee.camel@mailoo.org>
Date:   Mon, 22 Feb 2021 21:51:39 +0100
From:   Vincent Knecht <vincent.knecht@...loo.org>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Henrik Rydberg <rydberg@...math.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Michael Srba <Michael.Srba@...nam.cz>,
        linux-input@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, ~postmarketos/upstreaming@...ts.sr.ht
Subject: Re: [PATCH v4 2/2] Input: add MStar MSG2638 touchscreen driver

Le samedi 20 février 2021 à 15:23 -0800, Dmitry Torokhov a écrit :
> Hi Vincent,

Hi Dmitry, thank you for the review !

> On Wed, Feb 10, 2021 at 06:33:52PM +0100, Vincent Knecht wrote:
> > +
> > +       for (i = 0; i < MAX_SUPPORTED_FINGER_NUM; i++) {
> > +               p = &touch_event.pkt[i];
> > +               /* Ignore non-pressed finger data */
> > +               if (p->xy_hi == 0xFF && p->x_low == 0xFF && p->y_low == 0xFF)
> > +                       continue;
> > +
> > +               coord.x = (((p->xy_hi & 0xF0) << 4) | p->x_low) * msg2638->prop.max_x / TPD_WIDTH;
> > +               coord.y = (((p->xy_hi & 0x0F) << 8) | p->y_low) * msg2638->prop.max_y / TPD_HEIGHT;
> > +               msg2638_report_finger(msg2638, i, &coord);
> 
> We do not scale the coordinates in the kernel. Rather we provide
> resolution, if known, and min/max coordinates reported by the hardware,
> and let userspace handle the rest.

Ok, will remove scaling... I was able to test it's ok by setting 
touchscreen-size-{x,y} = <2048>;

> > +static int __maybe_unused msg2638_suspend(struct device *dev)
> > +{
> > +       struct i2c_client *client = to_i2c_client(dev);
> > +       struct msg2638_ts_data *msg2638 = i2c_get_clientdata(client);
> > +
> > +       mutex_lock(&msg2638->input_dev->mutex);
> > +
> > +       if (input_device_enabled(msg2638->input_dev))
> > +               msg2638_stop(msg2638);
> 
> I believe that you should power down the device only if it is not
> configures as wakeup source. In fact (and I think most drivers are
> wrong in this), you may want to power up the device if it is a wakeup
> source and it does not have any users.

I don't know much on this subject ; from downstream code, it seems
the touchscreen supports "wakeup gestures" (like "double click",
up/down/left/right directions and some characters/letters) and apparently
an irq-gpio which would be used to wakeup.
I don't handle that currently, is it required ?