[PATCH 1/4 v2] i2c/gpio: add DT support

Russell King - ARM Linux linux at arm.linux.org.uk
Mon Feb 20 10:03:22 EST 2012


On Mon, Feb 20, 2012 at 03:51:37PM +0100, Jean-Christophe PLAGNIOL-VILLARD wrote:
> On 13:51 Mon 20 Feb     , Russell King - ARM Linux wrote:
> > On Mon, Feb 20, 2012 at 02:35:57PM +0100, Jean Delvare wrote:
> > > On Mon, 20 Feb 2012 12:50:54 +0000, Russell King - ARM Linux wrote:
> > > > What is linux specific is specifying the _delay_ rather than specifying
> > > > the bus frequency.  So as soon as you're trying to justify not adding
> > > > the units because they may be linux specific, you've already lost that
> > > > argument by using a delay rather than a bus frequency.  You can't have
> > > > it both ways.
> > > 
> > > While I am not much into DT and did not follow this thread too
> > > carefully... I seem to understand that the dispute is mainly on
> > > frequency vs. udelay specification for the bus speed, Jean-Christophe
> > > arguing that hardware-specific delays are added when changing e.g. a
> > > GPIO pin output value and thus the frequency can't be guaranteed. Do I
> > > get this right?
> > 
> > This sub-thread is more about the units of the properties rather
> > than the properties themselves.
> > 
> > What's being proposed is to have two properties, one named 'udelay'
> > which takes microseconds, and one named 'timeout' which takes
> > milliseconds.
> > 
> > I'm saying that's a completely absurd proposal, as the proposal is
> > for two opaque numeric properties with different units.  At least
> > make the units the same, or as Karol said, incorporate the units
> > into the property names.
> > 
> > At least we can then create new properties in the future of we need
> > to change the units, rather than thinking up a different name for
> > 'timeout'.
> 
> please read the binding
> 
> we have 2 properties
> 
>  - udelay: delay between GPIO operations (may depend on each platform)
>  - timeout: timeout to get data (ms)
> 
>  please do not mixed them together
> 
> udelay is related to bus frequency
> 
> timeout is implelentation detail, that allow to parameter the timeout og i2c
> bit algo when reading the scl on slow device

FOR FUCKING SAKE.  MILLISECONDS FOR SOME STUFF VS MICROSECONDS FOR OTHER
STUFF IS BAD NEWS.  FIX THIS AND I WILL WITHDRAW MY NACK.  CONTINUE BEING
OBSTRUCTIVE OVER THIS AND MY NACK STANDS.

I HOPE USING BIG LETTERS HELPS TO GET MY POINT THROUGH.



More information about the linux-arm-kernel mailing list