Messages in this thread |  | | Date | Tue, 18 Mar 2008 17:31:16 +0100 (CET) | From | Guennadi Liakhovetski <> | Subject | Re: gpio patches in mmotm |
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Please, do not trim the CC: list. I've also added lkml.
On Tue, 18 Mar 2008, Uwe Kleine-KЖnig wrote:
> Guennadi Liakhovetski wrote: > > On Mon, 17 Mar 2008, Uwe Kleine-KЖnig wrote: > > > > > I'm nure sure if I like gpio_is_valid(). When do you think it should be > > > used? (i.e. in which situations gpio_request doesn't do the right > > > thing?) > > > > For example, in situations similar to what I have in mt9m001 and mt9v022 > > camera drivers. Those cameras can be built with an i2c gpio extender, > > which can be used to switch between 8 and 10 bit data bus widths. But that > > extender is not always available. So, those drivers request a gpio, and if > > it is not available on the system, the gpio_is_valid() test fails. > I found your patch, but no tree where it applies. Can you point me to a > tree where it applies?
These drivers are currently in the v4l-dvb tree http://git.kernel.org/?p=linux/kernel/git/mchehab/v4l-dvb.git;a=summary in the devel branch.
> Why isn't it enough that gpio_request fails in such a situation?
I'm storing the GPIO number locally, and if the system doesn't have a valid GPIO for me, I'm storing an invalid GPIO number. Then at any time if the GPIO has to be used, I just verify if gpio_is_valid(), and if not, return an error code for this request, but the driver remains otherwise functional.
Thanks Guennadi --- Guennadi Liakhovetski -- 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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