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    SubjectRe: [PATCH] ARM: clk: add clk-asm9260 driver
    Date
    Quoting Oleksij Rempel (2015-01-15 01:45:32)
    > Am 15.01.2015 um 00:02 schrieb Mike Turquette:
    > > Quoting Oleksij Rempel (2015-01-08 00:59:27)
    > >> diff --git a/drivers/clk/clk-asm9260.c b/drivers/clk/clk-asm9260.c
    > >> new file mode 100644
    > >> index 0000000..6b1c220
    > >> --- /dev/null
    > >> +++ b/drivers/clk/clk-asm9260.c
    > >
    > > <snip>
    > >
    > >> +static const char *clk_names[] = {
    > >> + [REFCLK] = "oscillator",
    > >> + [SYSPLL] = "pll",
    > >> + [I2S0_MCLK] = "i2s0_mclk",
    > >> + [I2S1_MCLK] = "i2s1_mclk",
    > >> + [RTC_OSC] = "rtc_osc",
    > >> + [USB_PLL] = "usb_pll",
    > >> +};
    > >
    > > Why keep this list of names? Only clk_names[REFCLK] is used below and it
    > > is overwritten by the name supplied by DT.
    >
    > Ok.
    >
    > > <snip>
    > >
    > >> +static void __init asm9260_acc_init(struct device_node *np)
    > >> +{
    > >> + struct clk *clk;
    > >> + u32 rate;
    > >> + int n;
    > >> + u32 accuracy = 0;
    > >> +
    > >> + base = of_io_request_and_map(np, 0, np->name);
    > >> + if (!base)
    > >> + panic("%s: unable to map resource", np->name);
    > >> +
    > >> + /* register pll */
    > >> + rate = (ioread32(base + HW_SYSPLLCTRL) & 0xffff) * 1000000;
    > >> +
    > >> + clk_names[REFCLK] = of_clk_get_parent_name(np, 0);
    > >> + accuracy = clk_get_accuracy(__clk_lookup(clk_names[REFCLK]));
    > >> + clk = clk_register_fixed_rate_with_accuracy(NULL, clk_names[SYSPLL],
    > >> + clk_names[REFCLK], 0, rate, accuracy);
    > >
    > > This is different. Why do the PLLs inherit REFCLKs accuracy? Please see
    > > __clk_recalc_accuracies in drivers/clk/clk.c if you haven't already. We
    > > propagate accuracy through the clock tree already.
    >
    > clk_register_fixed_rate overwrite accuracy to 0. If i use
    > clk_register_fixed_rate, then half of my clocks has accuracy = 0.

    Ah, interesting. This is a bug that should be fixed. If a fixed-rate
    clock has a parent with a non-zero accuracy then we should propagate
    that accuracy value at registration-time. I'll look into this soon and
    your solution is fine for now. We can always clean it up later.

    >
    > >> +
    > >> + if (IS_ERR(clk))
    > >> + panic("%s: can't register REFCLK. Check DT!", np->name);
    > >> +
    >
    > <snip>
    >
    > >> +
    > >> + /* register clk-provider */
    > >> + clk_data.clks = clks;
    > >> + clk_data.clk_num = MAX_CLKS;
    > >> + of_clk_add_provider(np, of_clk_src_onecell_get, &clk_data);
    > >> + return;
    > >> +fail:
    > >> + iounmap(base);
    > >> +}
    > >> +CLK_OF_DECLARE(asm9260_acc, "alphascale,asm9260-clock-controller",
    > >> + asm9260_acc_init);
    > >
    > > Where is the DT binding definition for this clock provider?
    > >
    > > Thanks,
    > > Mike
    > >
    >
    > do you mean this patch?
    > http://lists.infradead.org/pipermail/linux-arm-kernel/2014-October/293147.html
    > (probably not last version)
    > Should i resend it to you?

    No need to resend. DT binding description looks fine (you can add my
    Reviewed-by if it is not yet merged), but I like to make sure that the
    code doesn't get merged before the binding definition.

    Regards,
    Mike

    >
    > --
    > Regards,
    > Oleksij
    >


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