linux-kernel - Re: gpio patches in mmotm

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 18 Mar 2008 17:31:16 +0100 (CET)
From:	Guennadi Liakhovetski <g.liakhovetski@...gutronix.de>
To:	Uwe Kleine-König <Uwe.Kleine-Koenig@...i.com>
cc:	David Brownell <david-b@...bell.net>, linux-kernel@...r.kernel.org
Subject: Re: gpio patches in mmotm

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@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/