Re: pinebook status update (20200215)

[Jason Thorpe <thorpej%me.com@localhost>]

> On Feb 15, 2020, at 12:55 PM, Jason Thorpe <thorpej%me.com@localhost> wrote:
> 
> I have identified which commit broke the display controller (if I roll back this single commit, everything works again).  Now I just need to understand WHY it broke it -- it was not a big change, and is probably just exposing a latent bug elsewhere.

Well, I spent most of the afternoon trying to figure out exactly what is wrong with the sunxitwi driver (which uses sys/dev/i2c/gttwsi_core.c), and I'm stumped... interrupt-driven mode just goes off the rails for some reason, and the hardware behaves in ways totally contrary to the documentation.  So, I gave up and checked in a work-around that simply disables interrupt-driven mode:

src/sys/dev/i2c/gttwsi_core.c
----------------------------
revision 1.16
date: 2020-02-15 23:42:01 +0000;  author: thorpej;  state: Exp;  lines: +9 -2;  commitid: EIAWG5IV4bkqpPWB;
Interrupt-driven I/O seems to completely go off the rails, at least
on AllWinner implementations of this controller, so force polled mode
for now.
----------------------------

With this change, X is working on my 9.99.46 Pinebook again.

-- thorpej