Messages in this thread | | | Date | Tue, 13 Jan 2015 12:35:38 +0100 | From | Wolfram Sang <> | Subject | Re: [PATCH v5 2/2] i2c: cadence: Check for errata condition involving master receive |
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> @@ -541,6 +541,18 @@ static int cdns_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, > * processed with a repeated start. > */ > if (num > 1) { > + /* > + * This controller does not give completion interrupt after a > + * master receive transfer if HOLD bit is set (repeated start), > + * resulting in SW timeout. Hence, if a receive transfer is > + * followed by any other transfer, an error is returned > + * indicating that this sequence is not supported. > + */ > + for (count = 0; count < num-1; count++) { > + if (msgs[count].flags & I2C_M_RD) > + dev_warn(adap->dev.parent, "No support for repeated start when receive is followed by a transfer\n"); > + return -EOPNOTSUPP; > + } > id->bus_hold_flag = 1; > reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET); > reg |= CDNS_I2C_CR_HOLD;
Have you ever tested this code? There is a huge bug in it :(
Also, in the comment, use "message" instead of "transfer". One transfer consists of multiple messages.
Maybe the warning can be simplified, too: "can't do repeated start after read messages".
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