linux-kernel - RE: [EXT] Re: [v2 2/3] clk: ls1028a: Add clock driver for Display output interface

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Date:   Tue, 20 Aug 2019 02:24:25 +0000
From:   Wen He <wen.he_1@....com>
To:     Stephen Boyd <sboyd@...nel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>,
        "linux-devel@...ux.nxdi.nxp.com" <linux-devel@...ux.nxdi.nxp.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Mark Rutland <mark.rutland@....com>,
        Michael Turquette <mturquette@...libre.com>,
        Rob Herring <robh+dt@...nel.org>,
        Shawn Guo <shawnguo@...nel.org>
CC:     Leo Li <leoyang.li@....com>,
        "liviu.dudau@....com" <liviu.dudau@....com>
Subject: RE: [EXT] Re: [v2 2/3] clk: ls1028a: Add clock driver for Display
 output interface



> -----Original Message-----
> From: Stephen Boyd <sboyd@...nel.org>
> Sent: 2019年8月20日 2:30
> To: devicetree@...r.kernel.org; linux-clk@...r.kernel.org;
> linux-devel@...ux.nxdi.nxp.com; linux-kernel@...r.kernel.org; Mark Rutland
> <mark.rutland@....com>; Michael Turquette <mturquette@...libre.com>;
> Rob Herring <robh+dt@...nel.org>; Shawn Guo <shawnguo@...nel.org>; Wen
> He <wen.he_1@....com>
> Cc: Leo Li <leoyang.li@....com>; liviu.dudau@....com
> Subject: RE: [EXT] Re: [v2 2/3] clk: ls1028a: Add clock driver for Display output
> interface
> 
> Caution: EXT Email
> 
> Quoting Wen He (2019-08-19 00:30:49)
> > > Quoting Wen He (2019-08-15 03:16:12)
> > > > diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig index
> > > > 801fa1cd0321..3c95d8ec31d4 100644
> > > > --- a/drivers/clk/Kconfig
> > > > +++ b/drivers/clk/Kconfig
> > > > @@ -223,6 +223,16 @@ config CLK_QORIQ
> > > >           This adds the clock driver support for Freescale QorIQ
> platforms
> > > >           using common clock framework.
> > > >
> > > > +config CLK_LS1028A_PLLDIG
> > > > +        bool "Clock driver for LS1028A Display output"
> > > > +       depends on (ARCH_LAYERSCAPE || COMPILE_TEST) && OF
> > >
> > > Where is the OF dependency to build anything? Doesn't this still
> > > compile without CONFIG_OF set?
> >
> > Yes, current included some APIs of the OF, like of_get_parent_name()
> 
> And there isn't a stub API for of_get_parent_name when OF isn't defined?

You are right, should be remove OF dependency.

> 
> > > > +
> > > > +static int plldig_clk_probe(struct platform_device *pdev) {
> > > > +       struct clk_plldig *data;
> > > > +       struct resource *mem;
> > > > +       const char *parent_name;
> > > > +       struct clk_init_data init = {};
> > > > +       struct device *dev = &pdev->dev;
> > > > +       int ret;
> > > > +
> > > > +       data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> > > > +       if (!data)
> > > > +               return -ENOMEM;
> > > > +
> > > > +       mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > > > +       data->regs = devm_ioremap_resource(dev, mem);
> > > > +       if (IS_ERR(data->regs))
> > > > +               return PTR_ERR(data->regs);
> > > > +
> > > > +       init.name = dev->of_node->name;
> > > > +       init.ops = &plldig_clk_ops;
> > > > +       parent_name = of_clk_get_parent_name(dev->of_node, 0);
> > > > +       init.parent_names = &parent_name;
> > >
> > > Can you use the new way of specifying clk parents with the
> > > parent_data member of clk_init?
> >
> > Of course, but I don't understand why need recommend to use this member?
> > Is that the member parent_names will be discard in future?
> >
> > Here are definition of the clk-provider.h
> > /* Only one of the following three should be assigned */
> > const char              * const *parent_names;
> > const struct clk_parent_data    *parent_data;
> > const struct clk_hw             **parent_hws;
> >
> > For PLLDIG, it only has one parent.
> 
> Yes. Can you use clk_parent_data array and specify a DT index of 0 and some
> name that would go into "clock-names" in the .fw_name member?

OK, but .fw_name used for to registering clk, current it registered with fixed clk in dts .
I think should be specify a DT index of 0 and specify the unique name for .name member.

I found have two ways to specify:
1. declare clk_parent_data variable parent_data, and initialization with clk_init_data, like this:
 
parent_data.name = of_clk_get_parent_name(dev->of_node, 0); 
parent_data.index = 0;

init.name = dev->of_node->name;
init.ops = &plldig_clk_ops;
init.parent_data = &parent_data;
init.num_parents = 1;

2. Or use a static const array for here? And put the unique name and index like this.
static const struct clk_parent_data parent_data[] = {
        {.name = "phy_27m", .index = 0},
};

After then initialization with macro CLK_HW_INIT_PARENTS_DATA?

Best Regards,
Wen