Messages in this thread | | | Subject | Re: [patch 2.6.24-rc6-mm 8/9] gpiolib: pca9539 i2c gpio expander support | From | "Jean Delvare" <> | Date | Wed, 02 Jan 2008 14:46:03 +0100 |
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Hi David, hi Eric,
Le 29/12/2007, "David Brownell" <david-b@pacbell.net> a écrit: >From: eric miao <eric.miao@marvell.com> > >This adds a new-style I2C driver with basic support for the sixteen >bit PCA9539 GPIO expanders. These chips have multiple registers, >push-pull output drivers, and (not supported by this patch) pin >change interrupts. > >Board-specific code must provide "pca9539_platform_data" with each >chip's "i2c_board_info". That provides the GPIO numbers to be used >by that chip, and callbacks for board-specific setup/teardown logic. > >Derived from drivers/i2c/chips/pca9539.c (which has no current known >users). This is faster and simpler; it uses 16-bit register access, >and caches the OUTPUT and DIRECTION registers for fast access. > >Signed-off-by: eric miao <eric.miao@marvell.com> >Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> >--- > drivers/gpio/Kconfig | 10 + > drivers/gpio/Makefile | 1 > drivers/gpio/pca9539.c | 264 ++++++++++++++++++++++++++ > include/linux/i2c/pca9539.h | 18 +++ > 4 files changed, 293 insertions(+)
Random comments:
>+static int pca9539_gpio_get_value(struct gpio_chip *gc, unsigned off) >+{ >+ struct pca9539_chip *chip; >+ uint16_t reg_val; >+ int ret; >+ >+ chip = container_of(gc, struct pca9539_chip, gpio_chip); >+ >+ ret = pca9539_read_reg(chip, PCA9539_INPUT, ®_val); >+ if (ret < 0) { >+ /* NOTE: diagnostic already omitted; that's the >+ * best we can do here. >+ */ >+ return 0; >+ }
I guess that you really mean "emitted" here, not "omitted"?
More importantly, I don't agree that it's the best we can do here. Maybe it was already discussed before and there's a good reason to not report errors from "get" functions at the gpio-core level, but I can't see it. Whether a read error should be considered as "0" or "1" (or neither) should be a decision left to the user of the GPIO chip, rather than to each GPIO driver.
>+ >+ return (reg_val & (1u << off)) ? 1 : 0; >+}
>+static int __devinit pca9539_probe(struct i2c_client *client) >+{ >+ (...) >+ if (pdata->setup) { >+ ret = pdata->setup(client, chip->gpio_chip.base, >+ chip->gpio_chip.ngpio, pdata->context); >+ if (ret < 0) >+ dev_dbg(&client->dev, "setup failed, %d\n", ret);
Should be at least dev_warn() and maybe even dev_err().
>+ } >+ (...) >+} >+ >+static int pca9539_remove(struct i2c_client *client) >+{ >+ (...) >+ if (pdata->teardown) { >+ ret = pdata->teardown(client, chip->gpio_chip.base, >+ chip->gpio_chip.ngpio, pdata->context); >+ if (ret < 0) >+ dev_dbg(&client->dev, "teardown failed, %d\n", ret);
Same thing here.
>+ } >+ >+ ret = gpiochip_remove(&chip->gpio_chip); >+ if (ret) { >+ dev_err(&client->dev, "failed remove gpio_chip\n");
This error message could certainly be reworded to sound better. Also, for consistency you should include the value of "ret" in the message.
>+ return ret; >+ } >+ >+ kfree(chip); >+ return 0; >+}
-- Jean Delvare -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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