Hi Simon,
On Thu, Feb 4, 2021 at 5:42 AM Simon Glass <s...@chromium.org> wrote:
>
> Hi Bin,
>
> On Wed, 3 Feb 2021 at 07:42, Bin Meng <bmeng...@gmail.com> wrote:
> >
> > A working device tree node of ns16550 should never be populated
> > with value zero for the <clock-frequency> property. Unfortunately
> > this is the case for the QEMU ppce500 target.
> >
> > Let's try to assign plat->clock to CONFIG_SYS_NS16550_CLK as the
> > last resort to handle such case.
> >
> > This commit should be reverted when:
> >
> > - The following QEMU patch [1] is merged, and
> > - U-Boot CI has upgraded its QEMU version that contains the fix
> >
> > [1]
> > http://patchwork.ozlabs.org/project/qemu-devel/patch/1612362288-22216-2-git-send-email-bmeng...@gmail.com/
> >
> > Signed-off-by: Bin Meng <bmeng...@gmail.com>
> > ---
> >
> > drivers/serial/ns16550.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/serial/ns16550.c b/drivers/serial/ns16550.c
> > index da903c1..a1593a2 100644
> > --- a/drivers/serial/ns16550.c
> > +++ b/drivers/serial/ns16550.c
> > @@ -563,6 +563,8 @@ int ns16550_serial_of_to_plat(struct udevice *dev)
> > if (!plat->clock)
> > plat->clock = dev_read_u32_default(dev, "clock-frequency",
> > CONFIG_SYS_NS16550_CLK);
> > + if (!plat->clock)
> > + plat->clock = CONFIG_SYS_NS16550_CLK;
>
> This is already done in the line above...does that not work?
The line above only works if there is no <clock-frequency> in the
device tree. Since the device tree does provide a <clock-frequency>,
the default one was never used.
>
> > if (!plat->clock) {
> > debug("ns16550 clock not defined\n");
> > return -EINVAL;
Regards,
Bin
