On 05/21/2013 12:02 AM, Jongsung Kim wrote: > Stephen Warren reported the recent commit 78506f2 (add support for > extended FIFO-size of PL011-r1p5) breaks the serial port on the > BCM2835 ARM SoC. > > A UART compatible with the ARM PL011-r1p5 should have 32-deep FIFOs. > The BCM2835 UART just looks like an ARM PL011-r1p5, but has 16-deep > FIFOs just like PL011-r1p4 or earlier revisions. As a workaround for > this compatibility issue, this patch overrides the HW UART periphid > register values with the actually compatible UART periphid 0x00241011 > (r1p3 or r1p4). > > Reported-by: Stephen Warren <swarren@xxxxxxxxxxxxx> > Signed-off-by: Jongsung Kim <neidhard.kim@xxxxxxx> I know this will work, because I tried out the same thing last week. However, I'm not convinced that it's the correct approach. What other changes exist between r1p4 and r1p5; can you check in the TRM? Faking the periphid would prevent the driver from taking account of any other changes. Should we instead add a DT property solely to override the FIFO size, and then set that for bcm2835? I guess if there really aren't any other SW-visible changes in r1p5, this approach is fine. -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
