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

Sascha Hauer
2009-10-02T07:26:43Z

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.

> >
> >> Yes. But I don't have multi-master system. So I can't say that.
> >> The code is just taken from Freescale latest code. Without it, It
> >> could also cause a device error. I forget the details.  Anyway, it
> >> doesn't make anything wrong.
> >
> > Do you know where the details are explained?
> No, I don't. I don't have device in hand now. If you have, could you
> please help do a simple test?
> Use hw to simulate multi-master system. Before execute xfer, you first
> pull down SDA, then pull down SDC. It simulates a START. and execute
> xfer to see whether IBB is set?

No, we won't do any tests on hardware.

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.

Sascha

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