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Date: Wed, 6 Apr 2011 15:02:32 +0100
From: Alan Cox <alan@...rguk.ukuu.org.uk>
To: Jonathan Cameron <jic23@....ac.uk>
Cc: Alan Cox <alan@...ux.jf.intel.com>, linux-kernel@...r.kernel.org,
greg@...ah.com,
"linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>
Subject: Re: [PATCH] oaktrail AK8975 support via IIO
> >> +static int wait_conversion_complete_gpio(struct ak8975_data *data)
> >> +{
> >> + struct i2c_client *client = data->client;
> >> + u8 read_status;
> >> + u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT;
> >> + int ret;
> >> +
> >> + /* Wait for the conversion to complete. */
> >> + while (timeout_ms) {
> >> + msleep(AK8975_CONVERSION_DONE_POLL_TIME);
> >> + if (gpio_get_value(data->eoc_gpio))
> >> + break;
> >> + timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
> >> + }
> >> + if (!timeout_ms) {
> >> + dev_err(&client->dev, "Conversion timeout happened\n");
> >> + return -EINVAL;
> >> + }
> >> +
> >> + ret = ak8975_read_data(client, AK8975_REG_ST1, 1, &read_status);
> >> + if (ret < 0) {
> >> + dev_err(&client->dev, "Error in reading ST1\n");
> >> + return ret;
> >> + }
> >> + return read_status;
> >> +}
> >> +
> Its not immediately obvious to me why we need these two separate functions.
> They only differ by a couple of lines. Perhaps push querying if the gpio
> down into a single function?
That was actually my starting point but they are quite different - one
does the gpio check each loop then a read, the other does a read each
loop and then nothing. Mixed together you get
while() {
if
if
else
if
}
if
else
and it looks like spagetti ..
> >> +static int wait_conversion_complete_polled(struct ak8975_data *data)
> >> +{
> >> + struct i2c_client *client = data->client;
> >> + u8 read_status;
> >> + u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT;
> >> + int ret;
> >> +
> >> + /* Wait for the conversion to complete. */
> >> + while (timeout_ms) {
> >> + msleep(AK8975_CONVERSION_DONE_POLL_TIME);
> >> + ret = ak8975_read_data(client, AK8975_REG_ST1, 1, &read_status);
> >> + if (ret < 0) {
> >> + dev_err(&client->dev, "Error in reading ST1\n");
> >> + return ret;
> >> + }
> >> + if (read_status)
> >> + break;
> >> + timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
> >> + }
> >> + if (!timeout_ms) {
> >> + dev_err(&client->dev, "Conversion timeout happened\n");
> >> + return -EINVAL;
> >> + }
> >> + return read_status;
> >> +}
> >> +
> >> /*
> >> * Emits the raw flux value for the x, y, or z axis.
> >> */
> >> @@ -326,7 +379,6 @@ static ssize_t show_raw(struct device *dev, struct device_attribute *devattr,
> >> struct ak8975_data *data = indio_dev->dev_data;
> >> struct i2c_client *client = data->client;
> >> struct iio_dev_attr *this_attr = to_iio_dev_attr(devattr);
> >> - u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT;
> >> u16 meas_reg;
> >> s16 raw;
> >> u8 read_status;
> >> @@ -352,23 +404,14 @@ static ssize_t show_raw(struct device *dev, struct device_attribute *devattr,
> >> }
> >>
> >> /* Wait for the conversion to complete. */
> >> - while (timeout_ms) {
> >> - msleep(AK8975_CONVERSION_DONE_POLL_TIME);
> >> - if (gpio_get_value(data->eoc_gpio))
> >> - break;
> >> - timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
> >> - }
> >> - if (!timeout_ms) {
> >> - dev_err(&client->dev, "Conversion timeout happened\n");
> >> - ret = -EINVAL;
> >> + if (data->eoc_gpio)
> >> + ret = wait_conversion_complete_gpio(data);
> >> + else
> >> + ret = wait_conversion_complete_polled(data);
> >> + if (ret < 0)
> >> goto exit;
> >> - }
> >>
> >> - ret = ak8975_read_data(client, AK8975_REG_ST1, 1, &read_status);
> >> - if (ret < 0) {
> >> - dev_err(&client->dev, "Error in reading ST1\n");
> >> - goto exit;
> >> - }
> >> + read_status = ret;
> >>
> >> if (read_status & AK8975_REG_ST1_DRDY_MASK) {
> >> ret = ak8975_read_data(client, AK8975_REG_ST2, 1, &read_status);
> >> @@ -454,25 +497,26 @@ static int ak8975_probe(struct i2c_client *client,
> >> data->eoc_irq = client->irq;
> >> data->eoc_gpio = irq_to_gpio(client->irq);
> >>
> >> - if (!data->eoc_gpio) {
> >> - dev_err(&client->dev, "failed, no valid GPIO\n");
> >> - err = -EINVAL;
> >> - goto exit_free;
> >> - }
> >> -
> >> - err = gpio_request(data->eoc_gpio, "ak_8975");
> >> - if (err < 0) {
> >> - dev_err(&client->dev, "failed to request GPIO %d, error %d\n",
> >> - data->eoc_gpio, err);
> >> - goto exit_free;
> >> - }
> >> + /* We may not have a GPIO based IRQ to scan, that is fine, we will
> >> + poll if so */
> >> + if (data->eoc_gpio > 0) {
> >> + err = gpio_request(data->eoc_gpio, "ak_8975");
> >> + if (err < 0) {
> >> + dev_err(&client->dev,
> >> + "failed to request GPIO %d, error %d\n",
> >> + data->eoc_gpio, err);
> >> + goto exit_free;
> >> + }
> >>
> >> - err = gpio_direction_input(data->eoc_gpio);
> >> - if (err < 0) {
> >> - dev_err(&client->dev, "Failed to configure input direction for"
> >> - " GPIO %d, error %d\n", data->eoc_gpio, err);
> >> - goto exit_gpio;
> >> - }
> >> + err = gpio_direction_input(data->eoc_gpio);
> >> + if (err < 0) {
> >> + dev_err(&client->dev,
> >> + "Failed to configure input direction for GPIO %d, error %d\n",
> >> + data->eoc_gpio, err);
> >> + goto exit_gpio;
> Not really relevant to this patch, but this handling could be cleaned up using gpio_request_one.
> >> + }
> >> + } else
> >> + data->eoc_gpio = 0; /* No GPIO available */
> >>
> >> /* Perform some basic start-of-day setup of the device. */
> >> err = ak8975_setup(client);
> >> @@ -503,7 +547,8 @@ static int ak8975_probe(struct i2c_client *client,
> >> exit_free_iio:
> >> iio_free_device(data->indio_dev);
> >> exit_gpio:
> >> - gpio_free(data->eoc_gpio);
> >> + if (data->eoc_gpio)
> >> + gpio_free(data->eoc_gpio);
> >> exit_free:
> >> kfree(data);
> >> exit:
> >> @@ -517,7 +562,8 @@ static int ak8975_remove(struct i2c_client *client)
> >> iio_device_unregister(data->indio_dev);
> >> iio_free_device(data->indio_dev);
> >>
> >> - gpio_free(data->eoc_gpio);
> >> + if (data->eoc_gpio)
> >> + gpio_free(data->eoc_gpio);
> >>
> >> kfree(data);
> >>
> >>
> >
> > --
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> >
>
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--
--
"Alan, I'm getting a bit worried about you."
-- Linus Torvalds
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