Re: [PATCH 1/3] dt-bindings: clock: Update Hisilicon reset doc

[Jun Nie <jun.nie@linaro.org>]

Philipp Zabel <p.zabel@pengutronix.de> 于2019年12月3日周二 上午1:04写道：
>
> Hi Jun,
>
> I have a few questions and comments about these patches. I notice that
> the changed device trees only use the default setting. Are these new
> features something that is required for the present SoCs, or is this in
> preparation for a new SoC?

Yes, this patch set is prepared for new SoC.

>
> On Mon, 2019-12-02 at 22:45 +0800, Jun Nie wrote:
> > Document the update of Hisilicon reset operation extension.
> >
> > Signed-off-by: Jun Nie <jun.nie@linaro.org>
> > ---
> >  .../devicetree/bindings/clock/hisi-crg.txt    | 12 ++++----
> >  include/dt-bindings/reset/hisilicon-resets.h  | 28 +++++++++++++++++++
> >  2 files changed, 35 insertions(+), 5 deletions(-)
> >  create mode 100644 include/dt-bindings/reset/hisilicon-resets.h
> >
> > diff --git a/Documentation/devicetree/bindings/clock/hisi-crg.txt b/Documentation/devicetree/bindings/clock/hisi-crg.txt
> > index cc60b3d423f3..fd8b0a964806 100644
> > --- a/Documentation/devicetree/bindings/clock/hisi-crg.txt
> > +++ b/Documentation/devicetree/bindings/clock/hisi-crg.txt
> > @@ -26,19 +26,21 @@ to specify the clock which they consume.
> >
> >  All these identifier could be found in <dt-bindings/clock/hi3519-clock.h>.
> >
> > -- #reset-cells: should be 2.
> > +- #reset-cells: should be 3.
> >
> >  A reset signal can be controlled by writing a bit register in the CRG module.
> > -The reset specifier consists of two cells. The first cell represents the
> > +The reset specifier consists of three cells. The first cell represents the
> >  register offset relative to the base address. The second cell represents the
> > -bit index in the register.
> > +bit index in the register. The third represent the flags to operation type.
> > +
> > +All reset flags could be found in <dt-bindings/reset/hisilicon-resets.h>
> >
> >  Example: CRG nodes
> >  CRG: clock-reset-controller@12010000 {
> >       compatible = "hisilicon,hi3519-crg";
> >       reg = <0x12010000 0x10000>;
> >       #clock-cells = <1>;
> > -     #reset-cells = <2>;
> > +     #reset-cells = <3>;
> >  };
> >
> >  Example: consumer nodes
> > @@ -46,5 +48,5 @@ i2c0: i2c@12110000 {
> >       compatible = "hisilicon,hi3519-i2c";
> >       reg = <0x12110000 0x1000>;
> >       clocks = <&CRG HI3519_I2C0_RST>;
> > -     resets = <&CRG 0xe4 0>;
> > +     resets = <&CRG 0xe4 0 (HISI_ASSERT_SET | HISI_DEASSERT_CLEAR)>;
> >  };
> > diff --git a/include/dt-bindings/reset/hisilicon-resets.h b/include/dt-bindings/reset/hisilicon-resets.h
> > new file mode 100644
> > index 000000000000..983e42a0c318
> > --- /dev/null
> > +++ b/include/dt-bindings/reset/hisilicon-resets.h
> > @@ -0,0 +1,28 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +/*
> > + * Hisilicon Reset definitions
> > + *
> > + * Copyright (c) 2019 HiSilicon Technologies Co., Ltd.
> > + */
> > +
> > +#ifndef __DT_BINDINGS_RESET_HISILICON_H__
> > +#define __DT_BINDINGS_RESET_HISILICON_H__
> > +
> > +/*
> > + * The reset does not support the feature and corresponding
> > + * values are not valid
> > + */
> > +#define HISI_ASSERT_NONE             (1 << 0)
> > +#define HISI_DEASSERT_NONE           (1 << 1)
>
> What is the purpose of these two? Surely a reset control that does
> nothing is not useful?
>
> > +
> > +/* When set this function is activated by polling/setting/clearing this bit */
> > +#define HISI_ASSERT_SET              (1 << 2)
> > +#define HISI_DEASSERT_SET            (1 << 3)
>
> > +#define HISI_ASSERT_CLEAR            (0 << 4)
> > +#define HISI_DEASSERT_CLEAR          (0 << 5)
> > +#define HISI_ASSERT_POLL             (0 << 6)
> > +#define HISI_DEASSERT_POLL           (0 << 7)
>
> These are all zero, checking for them with an & operation in the code
> always returns false.

Thanks for pointing out this! This is a typo in the early version
patch. I made some
mistake when preparing the patch for upstream. Will fix this issue.
>
> > +
> > +#define HISI_RESET_DEFAULT           (HISI_ASSERT_SET | HISI_DEASSERT_CLEAR)
> > +
> > +#endif
>
> regards
> Philipp
>