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

Richard Zhao
2009-10-02T00:57:04Z

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?
>
>> 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?

Thanks
Richard
>
> Regards,
>
>   Wolfram
>
> --
> Pengutronix e.K.                           | Wolfram Sang                |
> Industrial Linux Solutions                 | http://www.pengutronix.de/  |
>
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