On Mon, 2 Apr 2018 22:23:17 +0200 Peter Rosin <p...@axentia.se> wrote:
> > I don't use devmem2. Is 'readback' information accurate or is it > > always what's been written? Because when you write 0x33 to 0xFFFFECBC, > > 0x33 is read back, but just after that, when you read it again it's 0. > > Looking at the devmem2 source, it seems very likely that the compiler > optimizes out the read and thus outputs what has been written. Yep, had a look too, and it's missing a volatile specifier to prevent that sort of optimizations. > > >> BTW, how do I > >> know which master is in use for the LCD controller? 8 or 9? Both? > > > > It's configurable on a per-layer basis through the SIF bit in > > LCDC_<layer>CFG0. The driver tries to dispatch the load on those 2 AHB > > masters [1]. > > Ok, I only have one plane (in this case, i.e. no cursor, no overlays etc), > would that mean that only one master is used? Yep, it's always using the first one (master 8 on a sama5d3). -- Boris Brezillon, Bootlin (formerly Free Electrons) Embedded Linux and Kernel engineering https://bootlin.com
