[PATCH 0/2] serial, Malta: Fixes to make the CBUS UART work big-endian
From: "Maciej W. Rozycki" <macro@orcam.me.uk>
Date: 2021-06-10 18:37:59
Also in:
linux-serial, lkml
From: "Maciej W. Rozycki" <macro@orcam.me.uk>
Date: 2021-06-10 18:37:59
Also in:
linux-serial, lkml
Hi, Earlier this year I noticed the CBUS UART, a discrete TI16C550C part wired directly to the system controller's device bus and supposed to come up as ttyS2 in addition to ttyS0 and ttyS1 ports from a Super I/O device behind the PCI southbridge, is not recognised with my MIPS Malta board booting big-endian. I used to use it just fine, many many years ago, although in the board's little-endian configuration only, and then with a local patch to get it supported with Linux 2.4.x, which I didn't get to submitting however due to the turn of events back then. Support was then added by someone else with 2.6.23. I got to the bottom of the problem now and as it turns out we have two long-standing bugs causing it, one in generic 8250 code and another in Malta platform code, and this has never worked in the big-endian mode. Evidently, this has never been verified, and I guess this is because back in the MIPS UK days we usually ran the boards in the little-endian mode. This pair of patches addresses these bugs individually. See the respective change descriptions for details. Please apply. Maciej