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SubjectRe: [PATCH] i2c: imx: add slave support. v2 status
Hello Maxim,

Thank you very much for the intermediate patch. I am in the process of
reviewing it. Please let me clarify a few questions I have.

1. What alternative to "bus busy/bus free/IBB" polling do you have in
mind? This seems like a reasonable approach to me.
2. What are the major points you consider in need of refactoring?
3. You mention race conditions being fixed in this version relating to
bus-locking by the slave and breaking slave transactions by the master.
Does this mean mixed slave/master mode works to your satisfaction? If
not, what work still needs to be done here?
4. You mention the need for a slave locking test and a work-around
(checking IMX_I2C_I2DR and IBB) being in-place. Why is this work-around
not sufficient?

Thanks again,


On 10/28/2016 04:38 AM, Maxim Syrchin wrote:
> Hi,
> Sorry for huge delay in answering. Unfortunately we don't have enough
> resources now to prepare clean enough patch to be accepted by community.
> Please find the latest version attached. Driver has passed stress
> tests, but looks like it need seriuos refactoring (it is unnecessarily
> complicated).
> We still have polling in slave code. Since imx doesn't generate
> interrupt on "bus busy"/"bus free" events we have to test IBB bit in
> polling loop.
> Comparing to v2 version several race conditions were fixed (bus
> locking by slave, breaking slave transaction by starting master xfer).
> v2 is working pretty good in slave-only or master-only mode. It is
> reasonable to add slave locking test - sometimes imx6 hw doesn't
> release data line. As workaround we use dummy reading of IMX_I2C_I2DR
> if driver is in slave mode and IBB bit is set for a long time.
> Thanks,
> Maxim Syrchin
> 27.10.2016 10:31, Frkuska, Joshua пишет:
>> Hi Maxim, Dmitriy, Wolfram,
>> If there is no immediate plan for a third release of the below patch
>> set, would it be possible to continue with merging v2 after
>> addressing the remaining concerns?
>> Thank you and regards,
>> Joshua
>>> Hi Maxim,
>>> On 2016-03-04 11:06:10 in the thread "Re: [PATCH] i2c: imx: add
>>> slave support. v2"
>>> referenced here: you said:
>>>> Hi Wolfram,
>>>> I'm now working on creating new driver version. I think I'll be
>>>> able to
>>>> sent it soon.
>>> Do you still plan to release a driver update for an i2c imx driver
>>> slave support?
>>> Best regards,
>>> Jim Baxter

Joshua Frkuska | Embedded Software Engineer
Mentor Graphics Japan Co., ltd. | +81-3-6866-7611

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