linux-kernel - Re: [PATCH 6/10] clk: sunxi-ng: Add A10s CCU driver

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Date:   Mon, 21 Nov 2016 22:45:52 +0100
From:   Maxime Ripard <maxime.ripard@...e-electrons.com>
To:     Chen-Yu Tsai <wens@...e.org>
Cc:     Mike Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...eaurora.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-clk <linux-clk@...r.kernel.org>
Subject: Re: [PATCH 6/10] clk: sunxi-ng: Add A10s CCU driver

On Sun, Nov 13, 2016 at 05:34:44PM +0800, Chen-Yu Tsai wrote:
> > +static struct ccu_nkmp pll_ve_clk = {
> > +       .enable         = BIT(31),
> > +       .n              = _SUNXI_CCU_MULT_OFFSET(8, 5, 0),
> > +       .k              = _SUNXI_CCU_MULT(4, 2),
> > +       .m              = _SUNXI_CCU_DIV(0, 2),
> > +       .p              = _SUNXI_CCU_DIV(16, 2),
> 
> Any chance we'll support the bypass switch on this one?

I'm not sure this will be useful to have it running at 24MHz.

> > +static SUNXI_CCU_M(pll_ddr_clk, "pll-ddr", "pll-ddr-base", 0x020, 0, 2, 0);
> 
> Maybe we should set CLK_IS_CRITICAL on this one as well... in case the
> bootloader uses pll-periph for mbus, and none of the dram gates are enabled.

Ack.

> > +static SUNXI_CCU_GATE(hosc_clk,        "hosc", "osc24M", 0x050, BIT(0), 0);
> 
> Why the extra "hosc" clock here? You should probably just internalize "osc24M".

I'd prefer to model it as it is modelled in hardware: you have two
crystals, and then a gate within the CCU.

> > +static const char * const csi_parents[] = { "hosc", "pll-video0", "pll-video1",
> > +                                           "pll-video0-2x", "pll-video1-2x" };
> > +static const u8 csi_table[] = { 0, 1, 2, 5, 6 };
> > +static SUNXI_CCU_M_WITH_MUX_TABLE_GATE(csi_clk, "csi",
> > +                                      csi_parents, csi_table,
> > +                                      0x134, 0, 5, 24, 2, BIT(31), 0);
> 
> Do you know if CSI needs to change the module clock?

Apparently not.

Thanks!
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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