Messages in this thread | | | From | "" <> | Date | Fri, 20 Mar 2015 20:32:54 +0200 | Subject | Re: [PATCH v3 4/5] i2c: davinci: use bus recovery infrastructure |
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Hi, On 03/18/2015 10:31 PM, Wolfram Sang wrote: > Hi, > > so, the bus recovery patches look fine to me in general. > > It is only this one question left which I always had with bus recovery. > Maybe you guys can join me thinking about it.
Ok. Thanks and sorry for delayed reply - missed your e-mail :( I'll resend them next week.
> >> @@ -376,8 +366,7 @@ i2c_davinci_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg, int stop) >> dev->adapter.timeout); >> if (r == 0) { >> dev_err(dev->dev, "controller timed out\n"); >> - davinci_i2c_recover_bus(dev); >> - i2c_davinci_init(dev); >> + i2c_recover_bus(adap); >> dev->buf_len = 0; >> return -ETIMEDOUT; > > The I2C specs say in 3.1.16 that the recovery procedure should be used > when SDA is stuck low. So, I do wonder if we should apply the recovery > after a timeout. Stuck SDA might be one reason for timeout, but there > may be others...
This is ancient code. And regarding your question - Might be it would be reasonable to add call of i2c_davinci_wait_bus_not_busy() at the end of i2c_davinci_xfer()? This way we will wait for Bus Free before performing recovery.
Of course, i2c_davinci_wait_bus_not_busy() has to be fixed first as proposed by Alexander Sverdlin here: https://patchwork.ozlabs.org/patch/448994/.
-- regards, -grygorii
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