"Hunter, Jon" <jon-hunter@xxxxxx> writes: > Hi Kevin, > >> Shouldn't you do a read-modify-write of I2C_CON_REG here? Otherwise, >> you're loosing any of the other settings in I2C_CON_REG. >> >> Not being an expert in the I2C hardware, I'm not sure if it matters, >> but this doesn't seem quite right due to possible side effects. > > This is a good question and this exact same issue came up on the > omapzoom tree. For the omapzoom tree we ended up not implementing a > read-modify-write here. The reason being that omap_i2c_unidle is > called at the beginning of every transfer and we are re-configuring > the I2C_CON register for every transfer. So when consulting with the > TI linux team they said that it is ok to simply write 0 and clear > the register here so we start over fresh for each transfer. > > I was trying to think if there would be any harm in doing a > read-modify-write here. Probably not. You would not want the STT bit > (generate a start command) to get set, however, this bit should not > be set in the first place when entering this function. > > This change has been implemented in the omapzoom tree and so for you >reference please see: >http://git.omapzoom.org/?p=repo/omapkernel.git;a=commit;h=ec70a0af52df54638a4fa33fc0dc3d24b1f893f1 Jon, thanks for the clarification. I will fold this change into the upstream-bound I2C changes. Also thanks for the pointer to the original patch with author/signoff credits. Tao, in the future please be sure to cite original authors and/or sources when submitting patches to the list. Thanks, Kevin -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
