On 09/03/10 06:18, samu.p.onkalo@xxxxxxxxx wrote: > > >> -----Original Message----- >> From: linux-iio-owner@xxxxxxxxxxxxxxx [mailto:linux-iio- >> owner@xxxxxxxxxxxxxxx] On Behalf Of ext Alan Cox >> Sent: 03 September, 2010 01:20 >> To: achew@xxxxxxxxxx >> Cc: linux-kernel@xxxxxxxxxxxxxxx; linux-iio@xxxxxxxxxxxxxxx; linux- >> i2c@xxxxxxxxxxxxxxx; akpm@xxxxxxxxxxxxxxxxxxxx; khali@xxxxxxxxxxxx; >> ldewangan@xxxxxxxxxx >> Subject: Re: [PATCH 1/1] iio: ak8975: Add Ak8975 magnetometer sensor >> >>> +/* >>> + * Shows the device's mode. 0 = off, 1 = on. >>> + */ >> >> Should this not be handled by runtime pm nowdays ? >> >>> + if ((oval < 0) || (oval > 1)) { >>> + dev_err(dev, "mode value is not supported\n"); >>> + return -EINVAL; >>> + } >> >> ulong cannot be < 0 and doesn't need all the brackets >> >> >>> + /* Wait for the conversion to complete. */ >>> + while (timeout_ms) { >>> + msleep(AK8975_CONVERSION_DONE_POLL_TIME); >>> + state = (gpio_get_value(data->eoc_gpio) ? 1 : 0); >>> + if (state) >>> + break; >>> + timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME; >>> + } >> >> This makes some fairly specific wiring assumptions about how the ak8975 >> is configured. I'm looking at the ak8974 driver in our tree and also >> wondering if they can be combined sanely. > > With ak8974 chip, it is possible to have similar functionality without interrupt > pin. This is most probably true also for ak8975 chip. It is not good to assume > that everyone uses interrupt pin if the same functionally can be achieved > another way. I mean polling via I2C instead of checking GPIO state after the > sleep. Of course this can be done, but it's up to Andrew to decide whether he wants to. I think the usual principal of writing only what people currently need applies here. Perhaps a comment in the code to point out this could be done is a sensible compromise? > > Based on the this driver it seems that ak8974 and ak8975 are quite similar, but > also there are many differences like different register map. Maybe combining > these two makes implementation just messy. > > >> >>> + status = ak8975_read_data(client, AK8975_REG_ST1, 1, >> &read_status); >>> + if (!status) { >>> + dev_err(&client->dev, "Error in reading ST1\n"); >>> + return false; >> >> I would have expected these to return a meaningful error code not 0 ? >> >>> +static IIO_DEVICE_ATTR(mode, S_IRUGO | S_IWUSR, show_mode, >> store_mode, 0); >>> +static IIO_DEVICE_ATTR(magn_x_calibscale, S_IRUGO, show_calibscale, >> NULL, 0); >>> +static IIO_DEVICE_ATTR(magn_y_calibscale, S_IRUGO, show_calibscale, >> NULL, 1); >>> +static IIO_DEVICE_ATTR(magn_z_calibscale, S_IRUGO, show_calibscale, >> NULL, 2); >>> +static IIO_DEV_ATTR_MAGN_X(show_raw, AK8975_REG_HXL); >>> +static IIO_DEV_ATTR_MAGN_Y(show_raw, AK8975_REG_HYL); >>> +static IIO_DEV_ATTR_MAGN_Z(show_raw, AK8975_REG_HZL); >> >> This seems odd as an interface as it's raw when the maths to provide >> non-raw (and thus abstract and easy for user space) data is trivial >> enough to do in kernel >> >> (but then I still suspect it should jusst be an input device of course) >> >>> +static int ak8975_probe(struct i2c_client *client, >>> + const struct i2c_device_id *id) >>> +{ >>> + struct ak8975_data *data; >>> + int err; >>> + >>> + /* Allocate our device context. */ >>> + data = kzalloc(sizeof(struct ak8975_data), GFP_KERNEL); >>> + if (!data) { >>> + dev_err(&client->dev, "Memory allocation fails\n"); >>> + err = -ENOMEM; >>> + goto exit; >>> + } >>> + >>> + i2c_set_clientdata(client, data); >>> + data->client = client; >>> + >>> + mutex_init(&data->lock); >>> + >>> + /* Grab and set up the supplied GPIO. */ >>> + data->eoc_irq = client->irq; >>> + data->eoc_gpio = irq_to_gpio(client->irq); >> >> It may not be via a GPIO. Better to do the GPIO handling in platform >> abstraction or accept passing IRQ and no GPIO value to mean "just use >> the >> IRQ". Ie do all the gpio foo if (data->eoc_gpio) { ... } >> >> >>> + >>> + 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); >>> + gpio_free(data->eoc_gpio); >> >> This frees the GPIO twice ? >> >> Looks basically sound to me. >> >> Alan -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
