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Message-ID: <4D9C7374.2050104@cam.ac.uk>
Date: Wed, 06 Apr 2011 15:06:44 +0100
From: Jonathan Cameron <jic23@....ac.uk>
To: Alan Cox <alan@...rguk.ukuu.org.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
On 04/06/11 15:02, Alan Cox wrote:
>>>> +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 ..
Good point. I clearly didn't look closely enough.
Acked-by: Jonathan Cameron <jic23@....ac.uk>
>
>
>
>
>>>> +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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