Re: [PATCH V4 08/11] clk: imx: imx8qxp-lpcg: add parsing clocks from device tree

From: Dong Aisheng <dongas86@gmail.com>
To: Stephen Boyd <sboyd@kernel.org>
Cc: Dong Aisheng <aisheng.dong@nxp.com>,
	linux-clk <linux-clk@vger.kernel.org>,
	"moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
	<linux-arm-kernel@lists.infradead.org>,
	Michael Turquette <mturquette@baylibre.com>,
	Shawn Guo <shawnguo@kernel.org>,
	Fabio Estevam <fabio.estevam@nxp.com>,
	dl-linux-imx <linux-imx@nxp.com>,
	Sascha Hauer <kernel@pengutronix.de>
Subject: Re: [PATCH V4 08/11] clk: imx: imx8qxp-lpcg: add parsing clocks from device tree
Date: Mon, 9 Sep 2019 19:23:14 +0800	[thread overview]
Message-ID: <CAA+hA=QJwfHsRA+G2oT2awLxx659qXLPsiECV6VYcJ181c6D8w@mail.gmail.com> (raw)
In-Reply-To: <20190906171323.8847820640@mail.kernel.org>

]On Sat, Sep 7, 2019 at 5:35 PM Stephen Boyd <sboyd@kernel.org> wrote:
>
> Quoting Dong Aisheng (2019-08-20 04:13:22)
> > Add parsing clocks from device tree.
>
> Please describe some more here.

Will improve.

> > +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +       base = devm_ioremap_resource(&pdev->dev, res);
> > +       if (IS_ERR(base))
> > +               return PTR_ERR(base);
> > +
> > +       count = of_property_count_u32_elems(np, "clock-indices");
> > +       if (count < 0) {
> > +               dev_err(&pdev->dev, "failed to count clocks\n");
> > +               return -EINVAL;
> > +       }
>
> Is 'count' expected to be equal to IMX_LPCG_MAX_CLKS? Because later on
> in this function we set the num of clks to the MAX instead of the count
> from clock-indices.
>

No. Here is a tricky to ease the clk getting.
For example, one LPCG supports up to 8 clock outputs which each of them
is fixed to 4 bits. Then we can easily use the bit-offset/clk-indices
parsed from DT
to fetch the corresponding clock by hws[clkspec->args[0] / 4].
And the cost is very limited with only a few pointers.

> > +
> > +       clk_data = devm_kzalloc(&pdev->dev, struct_size(clk_data, hws, IMX_LPCG_MAX_CLKS),
>
> This line is too long.
>

Will improve.

> > +                               GFP_KERNEL);
> > +       if (!clk_data)
> > +               return -ENOMEM;
> > +
> > +       clk_data->num = IMX_LPCG_MAX_CLKS;
> > +       clk_hws = clk_data->hws;
> > +
> > +       ret = of_property_read_u32_array(np, "clock-indices", bit_offset,
> > +                                        count);
> > +       if (ret < 0) {
> > +               dev_err(&pdev->dev, "failed to read clocks bit-offset\n");
>
> This isn't called bit-offset anymore.
>

Will improve.

> > +               return -EINVAL;
> > +       }
> > +
> > +       ret = of_clk_parent_fill(np, parent_names, count);
> > +       if (ret != count) {
> > +               dev_err(&pdev->dev, "failed to get clock parent names\n");
> > +               return -EINVAL;
>
> return count?
>

Okay

Regards
Aisheng