Heiko Stübner <heiko@xxxxxxxxx> writes: Hello Heiko, > Hi Peter, > > Am Dienstag, 4. April 2023, 14:52:02 CEST schrieb Peter Geis: >> On Tue, Apr 4, 2023 at 3:55 AM Heiko Stübner <heiko@xxxxxxxxx> wrote: >> > >> > Hi, >> > >> > Am Montag, 3. April 2023, 19:59:37 CEST schrieb Javier Martinez Canillas: >> > > This baud rate is set for the device by mainline u-boot and is also what >> > > is set in the Pinebook Pro Device Tree, which is a device similar to the >> > > PinePhone Pro but with a different form factor. >> > > >> > > Otherwise, the baud rate of the firmware and Linux don't match by default >> > > and a 'console=ttyS2,1500000n8' kernel command line parameter is required >> > > to have proper output for both. >> > >> > The interesting question is always if this will break someone else's setup. >> > I've never really understood the strange setting of 1.5MBps, but on the >> > other hand it _is_ a reality on most boards. > >> The 1.5M baud is default because the clock structure on rockchip >> devices does not allow a clean 115200 baud. By attempting to force >> 115200, it will always be slightly off (either low or high depending >> on how the driver decided to round). If this actually causes any >> problems is the subject of much debate. > > thanks so much for this piece of clock-detail. As I wrote, I never really > understood the why _before_ but also never cared that much to dive > into it and find out. > > So your explanation closes one knowledge gap in my head. > > Thanks a lot :-) Did you make a decision about this? I guess the clock explanation is yet another argument in favour of switching the PPP to a 1.5 Mbps baud rate ? -- Best regards, Javier Martinez Canillas Core Platforms Red Hat
