lkml.org 
[lkml]   [2015]   [Jan]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
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
>


\
 
 \ /
  Last update: 2015-01-19 18:41    [W:0.097 / U:15.700 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site