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Date: Wed, 2 Sep 2020 16:01:37 +0530
From: Nishant Malpani <nish.malpani25@...il.com>
To: Andy Shevchenko <andy.shevchenko@...il.com>
Cc: Jonathan Cameron <jic23@...nel.org>,
Rob Herring <robh+dt@...nel.org>,
"Bogdan, Dragos" <dragos.bogdan@...log.com>,
darius.berghe@...log.com,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
linux-iio <linux-iio@...r.kernel.org>,
devicetree <devicetree@...r.kernel.org>
Subject: Re: [PATCH 1/3] iio: gyro: adxrs290: Add triggered buffer support
Hello,
Thanks for the review, Andy. Comments inline...
On 26/08/20 9:40 pm, Andy Shevchenko wrote:
> On Tue, Aug 25, 2020 at 4:11 PM Nishant Malpani
> <nish.malpani25@...il.com> wrote:
>>
>> Provide a way for continuous data capture by setting up buffer support. The
>> data ready signal exposed at the SYNC pin of the ADXRS290 is exploited as
>> a hardware interrupt which triggers to fill the buffer.
>>
>> Triggered buffer setup was tested with both hardware trigger (DATA_RDY) and
>> software triggers (sysfs-trig & hrtimer).
>
> ...
>
>> +static int adxrs290_set_mode(struct iio_dev *indio_dev, enum adxrs290_mode mode)
>> +{
>> + struct adxrs290_state *st = iio_priv(indio_dev);
>> + int val, ret;
>> +
>> + mutex_lock(&st->lock);
>> +
>> + if (st->mode == mode) {
>
>> + ret = 0;
>
> Can be done outside of mutex.
>
Yep, makes sense.
>> + goto done;
>> + }
>> +
>
>> + val = spi_w8r8(st->spi, ADXRS290_READ_REG(ADXRS290_REG_POWER_CTL));
>> + if (val < 0) {
>> + ret = val;
>> + goto done;
>> + }
>
> Consider other way around
> ret = ...
> ...
> val = ret;
>
I suppose that does make things consistent; will do so in v2.
>> + switch (mode) {
>> + case ADXRS290_MODE_STANDBY:
>> + val &= ~ADXRS290_MEASUREMENT;
>> + break;
>> + case ADXRS290_MODE_MEASUREMENT:
>> + val |= ADXRS290_MEASUREMENT;
>> + break;
>> + default:
>> + ret = -EINVAL;
>> + goto done;
>> + }
>> +
>> + ret = adxrs290_spi_write_reg(st->spi,
>> + ADXRS290_REG_POWER_CTL,
>> + val);
>> + if (ret < 0) {
>> + dev_err(&st->spi->dev, "unable to set mode: %d\n", ret);
>> + goto done;
>> + }
>> +
>> + /* update cached mode */
>> + st->mode = mode;
>> +
>> +done:
>> + mutex_unlock(&st->lock);
>> + return ret;
>> +}
>
> ...
>
>> + goto err_release;
>>
>> - return IIO_VAL_INT;
>> + ret = IIO_VAL_INT;
>> + break;
>> default:
>> - return -EINVAL;
>> + ret = -EINVAL;
>> + break;
>> }
>
>> +err_release:
>
> I didn't get the purpose of this. Wasn't the break statement enough?
>
It is indeed; I just thought the labeling was a preferred way to jump to
error handling paths. Will use just the 'break' in v2.
>> + iio_device_release_direct_mode(indio_dev);
>> + return ret;
>> case IIO_CHAN_INFO_SCALE:
>> switch (chan->type) {
>> case IIO_ANGL_VEL:
>
> ...
>
>> + goto err_release;
>
> Ditto.
>
Got it.
>> + }
>> +
>> /* caching the updated state of the high-pass filter */
>> st->hpf_3db_freq_idx = hpf_idx;
>> /* retrieving the current state of the low-pass filter */
>> lpf_idx = st->lpf_3db_freq_idx;
>> - return adxrs290_set_filter_freq(indio_dev, lpf_idx, hpf_idx);
>> + ret = adxrs290_set_filter_freq(indio_dev, lpf_idx, hpf_idx);
>> + break;
>> +
>> + default:
>> + ret = -EINVAL;
>> + break;
>> }
>>
>> - return -EINVAL;
>> +err_release:
>> + iio_device_release_direct_mode(indio_dev);
>> + return ret;
>> }
>
> ...
>
>> + val = (state ? ADXRS290_SYNC(ADXRS290_DATA_RDY_OUT) : 0);
>
> Purpose of outer parentheses?
> I personally find that more readable but I think I'm violating the
coding style in the kernel; will remove the parentheses in v2.
> ...
>
>> +static int adxrs290_probe_trigger(struct iio_dev *indio_dev)
>> +{
>> + struct adxrs290_state *st = iio_priv(indio_dev);
>> + int ret;
>> +
>> + if (!st->spi->irq) {
>> + dev_info(&st->spi->dev, "no irq, using polling\n");
>> + return 0;
>> + }
>> +
>> + st->dready_trig = devm_iio_trigger_alloc(&st->spi->dev,
>> + "%s-dev%d",
>> + indio_dev->name,
>> + indio_dev->id);
>> + if (!st->dready_trig)
>> + return -ENOMEM;
>> +
>> + st->dready_trig->dev.parent = &st->spi->dev;
>> + st->dready_trig->ops = &adxrs290_trigger_ops;
>> + iio_trigger_set_drvdata(st->dready_trig, indio_dev);
>> +
>> + ret = devm_request_irq(&st->spi->dev, st->spi->irq,
>> + &iio_trigger_generic_data_rdy_poll,
>> + IRQF_ONESHOT,
>> + "adxrs290_irq", st->dready_trig);
>> + if (ret < 0) {
>
>> + dev_err(&st->spi->dev, "request irq %d failed\n", st->spi->irq);
>> + return ret;
>
> return dev_err_probe(...);
>
Nice, wasn't aware of this. Thanks. Will use 'dev_err_probe()' in v2
wherever pointed.
With regards,
Nishant Malpani
>> + }
>> +
>> + ret = devm_iio_trigger_register(&st->spi->dev, st->dready_trig);
>> + if (ret) {
>
>> + dev_err(&st->spi->dev, "iio trigger register failed\n");
>> + return ret;
>
> return dev_err_probe(...);
>
>> + }
>> +
>> + indio_dev->trig = iio_trigger_get(st->dready_trig);
>> +
>> + return 0;
>> +}
>
> ...
>
>> + ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev,
>> + &iio_pollfunc_store_time,
>> + &adxrs290_trigger_handler, NULL);
>> + if (ret < 0) {
>
>> + dev_err(&spi->dev, "iio triggered buffer setup failed\n");
>> + return ret;
>
> return dev_err_probe(...);
>
>> + }
>
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