Hi, > Analyze and rework the PIO mode operation. The PIO mode operation > was unreliable on MX28, by analyzing the bus with LA, the checks > for when data were available or were to be sent were wrong. > > The PIO WRITE has to be completely reworked as it multiple problems. > The MX23 datasheet helped here, see comments in the code for details. > The problems boil down to: > - RUN bit in CTRL0 must be set after DATA register was written > - The PIO transfer must be 4 bytes long tops, otherwise use > clock stretching. > Both of these fixes are implemented. > > The PIO READ operation can only be done for up to four bytes as > we are unable to read out the data from the DATA register fast > enough. > > This patch also tries to document the investigation within the > code. > > Signed-off-by: Marek Vasut <marex@xxxxxxx> > Cc: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx> > Cc: Fabio Estevam <r49496@xxxxxxxxxxxxx> > Cc: Lucas Stach <l.stach@xxxxxxxxxxxxxx> > Cc: Shawn Guo <shawn.guo@xxxxxxxxxx> > Cc: Wolfram Sang <wsa@xxxxxxxxxxxxx> > Cc: <to-fleischer@xxxxxxxxxxx> I so far got confirmation from ALexandre this patch works. Can someone else test it please? I'd like to roll out a final version to close this issue. One question remain though -- shall we have the PIO as an experimental feature and disable it by default OR not ? Thanks! Best regards, Marek Vasut -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
