Hello Maxime, thank you for taking the time to review this patch set.
On 04/02/2016 12:34 PM, Maxime Ripard wrote: > Hi, > > On Fri, Mar 25, 2016 at 08:04:07PM +0100, Michael Haas wrote: >> The A20 processor provides a third I2C bus on pins PB20 and PB21. >> The A20-OLinuXino-LIME2 exposes this bus via its GPIO1 port. >> >> Olimex also provide a breakout board called the >> A20-OLinuXino-LIME2-UEXT. This change is required to properly >> support I2C on the UEXT connector found there. >> >> Signed-off-by: Michael Haas <h...@computerlinguist.org> > > What are the other options on that pin? Is it something exclusively > dedicated to i2c on the pin headers and the documentation, or is > anyone free to use that pin for whatever he wishes? > > Thanks, > Maxime I assume you are talking about the UEXT connector, not about PB20 and PB21. These are regular GPIO pins multiplexed with I2C, but no other function. Regarding UEXT: the A20-OLinuXino-LIME2-UEXT breakout board supports two use cases here. The first one: provide a simple adapter from the 0.05" pin headers on the olinuxino to the more common world of 0.1" headers. In this use case, you can plug the A20-OLinuXino-LIME2-UEXT intoany of LCD_CON or GIO-{1,2,3} and you're good to go. The second one: here, you want to use UEXT modules provided by Olimex. It's a simple connector exposing I2C, SPI and UART as mentioned by Priit. To use UEXT, you have to use GPIO-1 to get the correct pin mapping. Regarding the official documentation provided by Olimex. The A20-OLinuXino-Lime2_Rev_c.pdf shows the pins on GPIO-1 as PB20 and PB21. In the schematics for the breakout board, A20-OLinuXino-Lime2-UEXT_sch.pdf, the pins for the UEXT connector are labeled as PB20/SCK and PB21/SDA. This acknowledges the double use. However, PB20 and PB21 have pull-ups by default according to A20-OLinuXino-Lime2_Rev_c.pdf, which makes them a lot more useful as I2C than as GPIO. What originally prompted me to submit this patch: I bought a breakout board and a small LCD with UEXT connector together with my board. Then I found out that it doesn't work out of the box because i2c2 is not enabled. Since using UEXT is probably common for that particular vendor, I believe it should be enabled by default. Michael -- You received this message because you are subscribed to the Google Groups "linux-sunxi" group. To unsubscribe from this group and stop receiving emails from it, send an email to linux-sunxi+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.