On Sat, 28 Mar 2015 13:01:24 -0400 , Peter Hurley <[email protected]> wrote: > Hi Grant, > > On 03/27/2015 09:36 PM, Grant Likely wrote: > > On Sun, 01 Mar 2015 17:23:11 -0500 > > , Peter Hurley <[email protected]> > > wrote: > >> Hi Kevin, > >> > >> On 11/24/2014 06:36 PM, Kevin Cernekee wrote: > >>> If an earlycon (stdout-path) node is being used, check for "big-endian" > >>> or "native-endian" properties and pass the appropriate iotype to the > >>> driver. > >>> > >>> Note that LE sets UPIO_MEM (8-bit) but BE sets UPIO_MEM32BE (32-bit). The > >>> big-endian property only really makes sense in the context of 32-bit > >>> registers, since 8-bit accesses never require data swapping. > >>> > >>> At some point, the of_earlycon code may want to pass in the reg-io-width, > >>> reg-offset, and reg-shift parameters too. > >>> > >>> Signed-off-by: Kevin Cernekee <[email protected]> > >>> --- > >>> drivers/of/fdt.c | 7 ++++++- > >>> drivers/tty/serial/earlycon.c | 4 ++-- > >>> include/linux/serial_core.h | 2 +- > >>> 3 files changed, 9 insertions(+), 4 deletions(-) > >>> > >>> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c > >>> index 658656f..9d21472 100644 > >>> --- a/drivers/of/fdt.c > >>> +++ b/drivers/of/fdt.c > >>> @@ -794,6 +794,8 @@ int __init early_init_dt_scan_chosen_serial(void) > >>> > >>> while (match->compatible[0]) { > >>> unsigned long addr; > >>> + unsigned char iotype = UPIO_MEM; > >>> + > >>> if (fdt_node_check_compatible(fdt, offset, match->compatible)) { > >>> match++; > >>> continue; > >>> @@ -803,7 +805,10 @@ int __init early_init_dt_scan_chosen_serial(void) > >>> if (!addr) > >>> return -ENXIO; > >>> > >>> - of_setup_earlycon(addr, match->data); > >>> + if (of_fdt_is_big_endian(fdt, offset)) > >>> + iotype = UPIO_MEM32BE; > >>> + > >>> + of_setup_earlycon(addr, iotype, match->data); > >> > >> I know these got ACKs already but as you point out in the commit log, > >> earlycon _will_ need reg-io-width, reg-offset and reg-shift. Since the > >> distinction between early_init_dt_scan_chosen_serial() and > >> of_setup_earlycon() is arbitrary, I'd rather see of_setup_earlycon() > >> taught to properly decode of_serial driver bindings instead of a > >> stack of parameters to of_setup_earlycon(). > >> > >> In fact, this patch allows a mis-defined devicetree to bring up a > >> functioning earlycon because the 'big-endian' property is directly > >> associated with UPIO_MEM32BE, which will create incompatibility problems > >> when DT earlycon is fixed to decode the of_serial DT bindings. > > > > That's a good point. This hasn't been merged yet, so there isn't any > > impact on addressing this. I would propose that for consistency, the > > earlycon code should always default to 8-bit access. if big-endian > > accesses are required, then reg-io-width + big-endian must be specified. > > > > Something like the following would do it and would be future-proof. We > > can add support for 16 or 64bit big or little endian access if it ever > > became necessary. > > I was planning on adding MEM32BE support to OF earlycon on top of my > patch series 'OF earlycon cleanup', which adds full support for the > of_serial driver DT properties (among other things). > > Unfortunately, that series is waiting on two things: > 1. libfdt upstream patch, which I submitted but was referred back to me > to add test cases. That was 3 weeks ago and I simply haven't had a free > day to burn to figure out how their test matrix is organized. I don't > think that's going to change anytime soon; I might just abandon that patch > and do the string manipulation on the stack. > > ATM, earlycon is still broken if stdout-path options have been set.
I don't seem to have that patch. Can you send it to me please? I do have a thought though. Would it be better to teach fdt_path_offset() to recognize the ':' delimiter? It's never a valid character for a path. The unittests are easy. "make check" builds and runs them. Adding a test is as simple as editing tests/parent_offset.c. main() calls check_path() several times to test calls to fdt_path_offset(). The tests can be added directly to that file. g. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
