On Mon Dec 21 21:42, Scott Wood wrote: > On Wed, 2015-11-25 at 10:46 -0800, Curt Brune wrote: > > Currently for PowerPC systems using device tree, the legacy serial > > ports are allocated in the order by which they are found in the device > > tree structure. > > > > This can cause problems in cases where the device tree nodes are > > sysnthesized by an external program (kexec for example), which may not > > preserve the original order of the device tree nodes. This in turn > > can result in the serial console changing from ttyS0 to ttyS1 > > unexpectedly. > > > > This patch uses the 'cell-index' property (if present) to map UART > > device tree nodes to legacy serial port number. The cell-index > > property is widely used in all the Freescale .dts files for PowerPC. > > > > Signed-off-by: Curt Brune <curt@xxxxxxxxxxxxxxxxxxx> > > --- > > arch/powerpc/kernel/legacy_serial.c | 11 +++++++++-- > > 1 file changed, 9 insertions(+), 2 deletions(-) > > > > diff --git a/arch/powerpc/kernel/legacy_serial.c > > b/arch/powerpc/kernel/legacy_serial.c > > index 7b750c4..b717133 100644 > > --- a/arch/powerpc/kernel/legacy_serial.c > > +++ b/arch/powerpc/kernel/legacy_serial.c > > @@ -164,6 +164,8 @@ static int __init add_legacy_soc_port(struct device_node > > *np, > > u64 addr; > > const __be32 *addrp; > > struct device_node *tsi = of_get_parent(np); > > + int index = -1, len; > > + u32 *indexp; > > > > /* We only support ports that have a clock frequency properly > > * encoded in the device-tree. > > @@ -188,14 +190,19 @@ static int __init add_legacy_soc_port(struct > > device_node *np, > > if (addr == OF_BAD_ADDR) > > return -1; > > > > + /* Check if the ports have an ordering, defined by 'cell-index' */ > > + if (((indexp = (u32*)of_get_property(np, "cell-index", &len)) != > > NULL) && > > + (len == sizeof(u32))) > > + index = *indexp; > > const u32 * > > Or better, use of_read_number() or similar. > > -Scott > Ack. Thanks for the pointer. -Curt -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
