linux-kernel - Re: [PATCH v2 1/4] Input: Add driver for Cypress Generation 5 touchscreen

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Date:   Sun, 12 Dec 2021 21:45:48 -0800
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Alistair Francis <alistair23@...il.com>
Cc:     Alistair Francis <alistair@...stair23.me>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        devicetree <devicetree@...r.kernel.org>,
        linux-input <linux-input@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Mylene Josserand <mylene.josserand@...e-electrons.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Andreas Kemnade <andreas@...nade.info>,
        Henrik Rydberg <rydberg@...math.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mylène Josserand 
        <mylene.josserand@...tlin.com>,
        Maxime Ripard <maxime.ripard@...tlin.com>
Subject: Re: [PATCH v2 1/4] Input: Add driver for Cypress Generation 5
 touchscreen

On Wed, Dec 01, 2021 at 10:27:46PM +1000, Alistair Francis wrote:
>  On Sat, Nov 6, 2021 at 4:47 PM Dmitry Torokhov
> <dmitry.torokhov@...il.com> wrote:
> >
> > Hi Alistair,
> >
> > On Wed, Nov 03, 2021 at 09:48:27PM +1000, Alistair Francis wrote:
> > > From: Mylčne Josserand <mylene.josserand@...tlin.com>
> > >
...
> > > +                            si->tch_hdr.max,
> > > +                            si->xy_mode + 3 + si->tch_hdr.ofs,
> > > +                            si->tch_hdr.bofs);
> > > +
> > > +     num_cur_tch = tch.hdr;
> > > +     if (num_cur_tch > max_tch) {
> > > +             dev_err(dev, "Num touch err detected (n=%d)\n", num_cur_tch);
> > > +             num_cur_tch = max_tch;
> > > +     }
> > > +
> > > +     if (num_cur_tch == 0 && ts->num_prv_rec == 0)
> > > +             return 0;
> > > +
> > > +     /* extract xy_data for all currently reported touches */
> > > +     if (num_cur_tch)
> > > +             cyttsp5_get_mt_touches(ts, &tch, num_cur_tch);
> > > +     else
> > > +             cyttsp5_mt_lift_all(ts);
> >
> > Not needed with INPUT_MT_DROP_UNUSED.
> 
> I tried INPUT_MT_DROP_UNUSED and I still need this function

I am curious why that is. Probably call to input_mt_sync_frame() was in
a wrong place?

...

> > > +
> > > +static int cyttsp5_deassert_int(struct cyttsp5 *ts)
> > > +{
> > > +     u16 size;
> > > +     u8 buf[2];
> > > +     int rc;
> > > +
> > > +     rc = regmap_bulk_read(ts->regmap, HID_INPUT_REG, buf, 2);
> > > +     if (rc < 0)
> > > +             return rc;
> > > +
> > > +     size = get_unaligned_le16(&buf[0]);
> > > +     if (size == 2 || size == 0)
> > > +             return 0;
> >
> > If you were to use level interrupts this probably would not be needed.
> 
> I have tried with/without this and I still can't get level interrupts working.

Does the platform support level interrupts?

...
> > > +static int cyttsp5_probe(struct device *dev, struct regmap *regmap, int irq,
> > > +                      const char *name)
> > > +{
> > > +     struct cyttsp5 *ts;
> > > +     struct cyttsp5_sysinfo *si;
> > > +     int rc = 0, i;
> > > +
> > > +     ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
> > > +     if (!ts)
> > > +             return -ENOMEM;
> > > +
> > > +     /* Initialize device info */
> > > +     ts->regmap = regmap;
> > > +     ts->dev = dev;
> > > +     si = &ts->sysinfo;
> > > +     dev_set_drvdata(dev, ts);
> > > +
> > > +     /* Initialize mutexes and spinlocks */
> > > +     mutex_init(&ts->system_lock);
> > > +
> > > +     /* Initialize wait queue */
> > > +     init_waitqueue_head(&ts->wait_q);
> > > +
> > > +     /* Power up the device */
> > > +     ts->vdd = regulator_get(dev, "vdd");
> >
> > Do not mix managed an unmanaged resources. You are leaking this
> > regulator.
> 
> I'm not clear what I should do differently here.

devm_regulator_get().

> 
> >
> > > +     if (IS_ERR(ts->vdd)) {
> > > +             rc = PTR_ERR(ts->vdd);
> > > +             dev_set_drvdata(dev, NULL);
> > > +             kfree(ts);

You can't call kfree() for memory allocated with devm_kzalloc().

> > > +             return rc;
> > > +     }
> > > +
> > > +     rc = regulator_enable(ts->vdd);
> > > +     if (rc) {
> > > +             regulator_put(ts->vdd);
> > > +             dev_set_drvdata(dev, NULL);
> > > +             kfree(ts);
> > > +             return rc;
> > > +     }
> > > +
> > > +     /* Reset the gpio to be in a reset state */
> > > +     ts->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
> > > +     if (IS_ERR(ts->reset_gpio)) {
> > > +             rc = PTR_ERR(ts->reset_gpio);
> > > +             dev_err(dev, "Failed to request reset gpio, error %d\n", rc);
> > > +             return rc;
> > > +     }
> > > +     gpiod_set_value(ts->reset_gpio, 1);
> > > +
> > > +     /* Need a delay to have device up */
> > > +     msleep(20);
> > > +
> > > +     rc = devm_request_threaded_irq(dev, irq, NULL, cyttsp5_handle_irq,
> > > +                                    IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
> >
> > Please do not override platform setup with hardcoded triggers. Also, it
> > is strongly recommended to use level interrupts for these peripherals.
> >
> > This is also likely unsafe if controller is not completely shut off and
> > is capable of generating interrupts given input device is not yet
> > allocated.
> 
> I have dropped the `IRQF_TRIGGER_FALLING |`
> 
> I have tried to use level interrupts, but I can't get the device
> working with them.

That is weird, does the interrupt controller support level interrupts?

Thanks.

-- 
Dmitry