Re: [PATCH 1/4] i2c: imx: check busy bit when START/STOP

Wolfram Sang
2009-10-02T14:11:06Z

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On Fri, Oct 02, 2009 at 04:17:09PM +0800, Richard Zhao wrote:
> On Fri, Oct 2, 2009 at 3:26 PM, Sascha Hauer <s.hauer-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org> wrote:
> > On Fri, Oct 02, 2009 at 08:57:04AM +0800, Richard Zhao wrote:
> >> On Fri, Oct 2, 2009 at 12:37 AM, Wolfram Sang <w.sang-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org> wrote:
> >> >> > Ah, so 'make the driver work on i.MX51' is a good statement which should
> >> >> > be part of the commit message.
> >> >> Well, maybe I can mention it.
> >> >> But I think the good point is to present what you modified, not the side effect.
> >> >
> >> > It is not the side effect but the intention :) As no code is changed without a
> >> > need, the reason really should be in the patch description.
> >> No, it's not intention. I'm just trying to make the controller work in
> >> a right way. Without this patch, maybe some other fast cpus have
> >> problem too. I just tested mx31 and mx51. I will add "Without this
> >> patch, i2c on some fast SoCs (for example imx51) will not work". Is it
> >> ok for you?
> >
> > Please remember that we do not have i.MX51 support in mainline, so this
> > is irrelevant atm.
> So I don't need to meantion mx51? "Without this patch, i2c on some
> fast SoCs will not work" is all right?

Sounds good to me!

> > At the moment we have a driver which is not multi master capable.
> > Looking at the datasheet the change you do seems not enough to change
> > this. So we should take a patch which changes something from which you
> > think it might be needed? And you don't even have the details at hand?
> >
> > No.
> Ok, It seems I have no reason to keep the busy wait before START.
> Wolfram, do you agree to remove the busy wait?

If somebody really needs multi-master and is able to test it, then it can be
reimplemented (but as said, this needs a lot more changes). Have to have a
closer look though, if it may detect a stalled bus.

> I saw you submmited the original driver.

I helped in getting it accepted, but the commit is mainly from Darius.

Regards,

Wolfram

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