[U-Boot] [PATCH 1/2] serial: add skipping init option

[Jun Nie]

Simon Glass <sjg at chromium.org> 于2019年3月31日周日 上午5:19写道：
>
> Hi Lukasz,
>
> On Wed, 27 Mar 2019 at 03:34, Lukasz Majewski <lukma at denx.de> wrote:
> >
> > Hi Simon, Jun,
> >
> > > Hi Jun,
> > >
> > > On Fri, 22 Mar 2019 at 16:02, Jun Nie <jun.nie at linaro.org> wrote:
> > > >
> > > > Simon Glass <sjg at chromium.org> 于2019年3月22日周五 下午3:56写道：
> > > > >
> > > > > Hi Jun,
> > > > >
> > > > > On Fri, 22 Mar 2019 at 15:20, Jun Nie <jun.nie at linaro.org>
> > > > > wrote:
> > > > > >
> > > > > > add skipping init option to avoid corrupt data in console
> > > > > > if serial is already initilized when u-boot start its excution.
> > > > > >
> > > > > > Signed-off-by: Jun Nie <jun.nie at linaro.org>
> > > > > > ---
> > > > > >  drivers/serial/Kconfig | 6 ++++++
> > > > > >  1 file changed, 6 insertions(+)
> > > > >
> > > > > Could we use a device-tree property for this? Some UARTs have a
> > > > > 'skip-init' property.
> > > > >
> > > > > Regards,
> > > > > Simon
> > > >
> > > > Hi Simon,
> > > >
> > > > It is a good suggestion. But device tree is board specific, while
> > > > the config is boot flow specific. For ATF -> OPTEE -> U-BOOT case,
> > > > initialization should be skipped. Without earlier initialization
> > > > from firmware, U-boot should do it by itself. So I need find a
> > > > solution that is defconfig specific, instead of device tree
> > > > specific.
> > >
> > > So you want something that is flow-specific, I think. Your thinking is
> > > that the defconfig specifies this. Is that because certain boards
> > > require ATF/Optee?
> > >
> > > Should we consider having a way to tell U-Boot that it is running
> > > from Optee?
> > >
> > > Could the UART driver detect that the UART is already inited?
> >
> > Isn't this issue similar to:
> > http://patchwork.ozlabs.org/patch/820824/
> >
> > and
> >
> > http://patchwork.ozlabs.org/patch/865963/
> >
>
> Yes. But in the case of this patch I'm hoping we don't need it.
>
> Regards,
> Simon

Right, we do not need patch here to skip the initialization. I already
add the fix in imx clock side to imx patch set. Thank for suggestion!

Jun