On Wed, 2017-01-25 at 00:23 +0100, Matthias Brugger wrote:
>
> On 01/20/2017 03:20 AM, Chunfeng Yun wrote:
> > On Thu, 2017-01-19 at 13:22 +0100, Matthias Brugger wrote:
> >>
> >> On 18/01/17 07:08, Chunfeng Yun wrote:
> >>> usually, the reference clock comes from 26M oscillator directly,
> >>> but some SoCs are not, add it for compatibility.
> >>>
> >>> Signed-off-by: Chunfeng Yun <chunfeng.yun@xxxxxxxxxxxx>
> >>> ---
> >>> drivers/usb/mtu3/mtu3.h | 1 +
> >>> drivers/usb/mtu3/mtu3_plat.c | 21 +++++++++++++++++++--
> >>> 2 files changed, 20 insertions(+), 2 deletions(-)
> > [...]
> >>> @@ -154,6 +162,7 @@ static int ssusb_rscs_init(struct ssusb_mtk *ssusb)
> >>> static void ssusb_rscs_exit(struct ssusb_mtk *ssusb)
> >>> {
> >>> clk_disable_unprepare(ssusb->sys_clk);
> >>> + clk_disable_unprepare(ssusb->ref_clk);
> >>> regulator_disable(ssusb->vusb33);
> >>> ssusb_phy_power_off(ssusb);
> >>> ssusb_phy_exit(ssusb);
> >>> @@ -216,6 +225,12 @@ static int get_ssusb_rscs(struct platform_device *pdev, struct ssusb_mtk *ssusb)
> >>> return PTR_ERR(ssusb->sys_clk);
> >>> }
> >>>
> >>> + ssusb->ref_clk = devm_clk_get(dev, "ref_ck");
> >>> + if (IS_ERR(ssusb->ref_clk)) {
> >>> + dev_err(dev, "failed to get ref clock\n");
> >>> + return PTR_ERR(ssusb->ref_clk);
> >>> + }
> >>> +
> >>
> >> That would break older dts bindings, right?
> > Yes, So I send a new patch for the related dts. Maybe it's not a
> > problem, only one dts file need be updated currently.
> >
> >> ref_ck must be optional for the code.
> > I tend to make it be optional for the dts, but not for the code.
> > There are some "fixed-clock" which can be treated as dummy ones, and if
> > a clock is really optional, we can use one fixed-clock in dts, and keep
> > the code simple.
> > In fact, the reference clock is essential for usb controller.
>
> Well the thing is that there are devices in the field with an older dtb
> which would break on a newer kernel. That's why we need to make it work
> with the old dtb in the code as well.
>
Happy Chinese New Year!
Ok, I will make it optional.
Thanks and sorry for later reply.
> Regards,
> Matthias
>
> >>
> >> Regards,
> >> Matthias
> >
> >
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