Re: [RESEND PATCH v5 3/5] IIO: Ingenic JZ47xx: Add touchscreen mode.

From: Paul Cercueil
Date: Fri Apr 17 2020 - 17:05:07 EST


Hi Andy,

Le ven. 17 avril 2020 à 23:59, Andy Shevchenko <andy.shevchenko@xxxxxxxxx> a écrit :
On Fri, Apr 17, 2020 at 11:21 PM Artur Rojek <contact@xxxxxxxxxxxxxx> wrote:

The SADC component in JZ47xx SoCs provides support for touchscreen
operations (pen position and pen down pressure) in single-ended and
differential modes.

Of the known hardware to use this controller, GCW Zero and Anbernic RG-350
utilize the touchscreen mode by having their joystick(s) attached to the
X/Y positive/negative input pins.
GCW Zero comes with a single joystick and is sufficiently handled with the
currently implemented single-ended mode. Support for boards with two
joysticks, where one is hooked up to Xn/Yn and the other to Xp/Yp channels
will need to be provided in the future.

The touchscreen component of SADC takes a significant time to stabilize
after first receiving the clock and a delay of 50ms has been empirically
proven to be a safe value before data sampling can begin.

All the boards which probe this driver have the interrupt provided from
devicetree, with no need to handle a case where the irq was not provided.

Device Tree
IRQ

...

+ .scan_type = {
+ .sign = 'u',
+ .realbits = 12,

+ .storagebits = 16

It's slightly better to leave comma in such cases.

+ },

+ .scan_type = {
+ .sign = 'u',
+ .realbits = 12,

+ .storagebits = 16

Ditto.

+ },

...

.indexed = 1,
.channel = INGENIC_ADC_AUX,
+ .scan_index = -1

Ditto. You see above? Isn't it nice that you didn't touch that line?
So, perhaps next developer can leverage this subtle kind of things.

.indexed = 1,
.channel = INGENIC_ADC_BATTERY,
+ .scan_index = -1

Ditto.

.indexed = 1,
.channel = INGENIC_ADC_AUX2,
+ .scan_index = -1

Ditto.

...

+static int ingenic_adc_buffer_enable(struct iio_dev *iio_dev)
+{
+ struct ingenic_adc *adc = iio_priv(iio_dev);
+

+ clk_enable(adc->clk);

Error check?

+ /* It takes significant time for the touchscreen hw to stabilize. */
+ msleep(50);
+ ingenic_adc_set_config(adc, JZ_ADC_REG_CFG_TOUCH_OPS_MASK,
+ JZ_ADC_REG_CFG_SAMPLE_NUM(4) |
+ JZ_ADC_REG_CFG_PULL_UP(4));
+ writew(80, adc->base + JZ_ADC_REG_ADWAIT);
+ writew(2, adc->base + JZ_ADC_REG_ADSAME);

+ writeb((u8)~JZ_ADC_IRQ_TOUCH, adc->base + JZ_ADC_REG_CTRL);

Why casting?

+ writel(0, adc->base + JZ_ADC_REG_ADTCH);
+ ingenic_adc_enable(adc, 2, true);
+
+ return 0;
+}

+ irq = platform_get_irq(pdev, 0);

Before it worked w/o IRQ, here is a regression you introduced.

Before it simply did not need the IRQ, which is provided by the devicetree anyway. No regression here.

-Paul


+ if (irq < 0) {

+ dev_err(dev, "Failed to get irq: %d\n", irq);

Redundant message.

+ return irq;
+ }

--
With Best Regards,
Andy Shevchenko