Re: [PATCH v2 5/7] clk: exynos: use cpu-clock provider type to represent arm clock

Lukasz Majewski
2014-01-21T10:39:04Z

Hi Thomas,

> On Mon, Jan 20, 2014 at 1:17 PM, Lukasz Majewski
> <l.majewski@samsung.com> wrote:
> > Hi Thomas,
> >
> >> From: Thomas Abraham <thomas.ab@samsung.com>
> >>
> >> With the addition of the new Samsung specific cpu-clock type, the
> >> arm clock can be represented as a cpu-clock type and the
> >> independent clock blocks that made up the arm clock can be removed.
> >>
> >> Signed-off-by: Thomas Abraham <thomas.ab@samsung.com>
> >> ---
> >> .../devicetree/bindings/clock/exynos5250-clock.txt | 1 +
> >> drivers/clk/samsung/clk-exynos4.c | 11
> >> +++++------ drivers/clk/samsung/clk-exynos5250.c
> >> | 8 ++++---- include/dt-bindings/clock/exynos5250.h
> >> | 1 + 4 files changed, 11 insertions(+), 10 deletions(-)
> >>
> >> diff --git
> >> a/Documentation/devicetree/bindings/clock/exynos5250-clock.txt
> >> b/Documentation/devicetree/bindings/clock/exynos5250-clock.txt
> >> index 99eae9c..acf867a 100644 ---
> >> a/Documentation/devicetree/bindings/clock/exynos5250-clock.txt +++
> >> b/Documentation/devicetree/bindings/clock/exynos5250-clock.txt @@
> >> -38,6 +38,7 @@ clock which they consume.
> >> ---------------------------- fin_pll 1
> >> + armclk 12
> >>
> >> [Clock Gate for Special Clocks]
> >>
> >> diff --git a/drivers/clk/samsung/clk-exynos4.c
> >> b/drivers/clk/samsung/clk-exynos4.c index 010f071..efcf4a3 100644
> >> --- a/drivers/clk/samsung/clk-exynos4.c
> >> +++ b/drivers/clk/samsung/clk-exynos4.c
> >> @@ -437,8 +437,6 @@ static struct samsung_mux_clock
> >> exynos4x12_mux_clks[] __initdata = {
> >> /* list of divider clocks supported in all exynos4 soc's */
> >> static struct samsung_div_clock exynos4_div_clks[] __initdata = {
> >> - DIV(0, "div_core", "mout_core", DIV_CPU0, 0, 3),
> >> - DIV(0, "div_core2", "div_core", DIV_CPU0, 28, 3),
> >> DIV(0, "div_fimc0", "mout_fimc0", DIV_CAM, 0, 4),
> >> DIV(0, "div_fimc1", "mout_fimc1", DIV_CAM, 4, 4),
> >> DIV(0, "div_fimc2", "mout_fimc2", DIV_CAM, 8, 4),
> >> @@ -484,8 +482,8 @@ static struct samsung_div_clock
> >> exynos4_div_clks[] __initdata = { DIV(0, "div_spi_pre2",
> >> "div_spi2", DIV_PERIL2, 8, 8), DIV(0, "div_audio1", "mout_audio1",
> >> DIV_PERIL4, 0, 4), DIV(0, "div_audio2", "mout_audio2", DIV_PERIL4,
> >> 16, 4),
> >> - DIV(CLK_ARM_CLK, "arm_clk", "div_core2", DIV_CPU0, 28, 3),
> >> - DIV(CLK_SCLK_APLL, "sclk_apll", "mout_apll", DIV_CPU0, 24,
> >> 3),
> >> + DIV_F(CLK_SCLK_APLL, "sclk_apll", "mout_apll", DIV_CPU0, 24,
> >> 3,
> >> + CLK_GET_RATE_NOCACHE, 0),
> >> DIV_F(0, "div_mipi_pre0", "div_mipi0", DIV_LCD0, 20, 4,
> >> CLK_SET_RATE_PARENT, 0),
> >> DIV_F(0, "div_mmc_pre0", "div_mmc0", DIV_FSYS1, 8, 8,
> >> @@ -870,7 +868,6 @@ static struct samsung_gate_clock
> >> exynos4x12_gate_clks[] __initdata = {
> >> static struct samsung_clock_alias exynos4_aliases[] __initdata = {
> >> ALIAS(CLK_MOUT_CORE, NULL, "moutcore"),
> >> - ALIAS(CLK_ARM_CLK, NULL, "armclk"),
> >> ALIAS(CLK_SCLK_APLL, NULL, "mout_apll"),
> >> };
> >>
> >> @@ -1125,12 +1122,14 @@ static void __init exynos4_clk_init(struct
> >> device_node *np, samsung_clk_register_alias(exynos4_aliases,
> >> ARRAY_SIZE(exynos4_aliases));
> >>
> >> + samsung_register_arm_clock(np, CLK_ARM_CLK, "mout_apll",
> >> reg_base); +
> >
> > I've got some doubts about allowing only the "mout_apll" clock to
> > be the only parent for armclk Samsung clock.
> >
> > For the Exynos4412 it is also valid to have SCLK_MPLL_USER_C [*] as
> > a parent for this clock.
> >
> > The problem is that you are reparenting the armclk to [*] with the
> > register modification - no CCF involved.
>
> The MUX_CORE mux is part of the larger cpu clock type and not
> registered as a separate mux clock with CCF. So I would like to know
> if there are any potential issues you see if this mux clock is
> internally managed within the set_rate of the larger cpu clock type.

So the large opaque clock (armclk) starts with inputs to MUX_CORE (and
embrace this MUX as well)?

If yes, then I don't mind if it is solely managed inside the armclk.

This however allows the armclk to be fed from mout_apll[*] and
sclk_mpll__user_c[**]. And this would be nice if reflected in the code.

>
> >
> > I just would like to know if this is yours design decision or
> > something, that we have overlooked in the v1 of this patch series.
>
> I did overlook this one. This will be fixed in the next version by
> ensuring that the dividers for SCLK_HPM clock will be updated only if
> mout_apll is the parent of the MUX_HPM clock mux.

Shall not they be updated if whatever connected to the MUX_HPM
([*] and [**]) changes?

>
> Thanks,
> Thomas.
>
> >
> >> pr_info("%s clocks: sclk_apll = %ld, sclk_mpll = %ld\n"
> >> "\tsclk_epll = %ld, sclk_vpll = %ld, arm_clk =
> >> %ld\n", exynos4_soc == EXYNOS4210 ? "Exynos4210" : "Exynos4x12",
> >> _get_rate("sclk_apll"),
> >> _get_rate("sclk_mpll"), _get_rate("sclk_epll"),
> >> _get_rate("sclk_vpll"),
> >> - _get_rate("arm_clk"));
> >> + _get_rate("armclk"));
> >> }
> >>
> >>
> >> diff --git a/drivers/clk/samsung/clk-exynos5250.c
> >> b/drivers/clk/samsung/clk-exynos5250.c index ff4beeb..487be36
> >> 100644 --- a/drivers/clk/samsung/clk-exynos5250.c
> >> +++ b/drivers/clk/samsung/clk-exynos5250.c
> >> @@ -298,9 +298,8 @@ static struct samsung_div_clock
> >> exynos5250_div_clks[] __initdata = { /*
> >> * CMU_CPU
> >> */
> >> - DIV(0, "div_arm", "mout_cpu", DIV_CPU0, 0, 3),
> >> - DIV(0, "div_apll", "mout_apll", DIV_CPU0, 24, 3),
> >> - DIV_A(0, "div_arm2", "div_arm", DIV_CPU0, 28, 3, "armclk"),
> >> + DIV_F(0, "div_apll", "mout_apll", DIV_CPU0, 24, 3,
> >> + CLK_GET_RATE_NOCACHE, 0),
> >>
> >> /*
> >> * CMU_TOP
> >> @@ -684,8 +683,9 @@ static void __init exynos5250_clk_init(struct
> >> device_node *np) ARRAY_SIZE(exynos5250_div_clks));
> >> samsung_clk_register_gate(exynos5250_gate_clks,
> >> ARRAY_SIZE(exynos5250_gate_clks));
> >> + samsung_register_arm_clock(np, CLK_ARM_CLK, "mout_apll",
> >> reg_base);
> >> pr_info("Exynos5250: clock setup completed, armclk=%ld\n",
> >> - _get_rate("div_arm2"));
> >> + _get_rate("armclk"));
> >> }
> >> CLK_OF_DECLARE(exynos5250_clk, "samsung,exynos5250-clock",
> >> exynos5250_clk_init); diff --git
> >> a/include/dt-bindings/clock/exynos5250.h
> >> b/include/dt-bindings/clock/exynos5250.h index 922f2dc..59a10fb
> >> 100644 --- a/include/dt-bindings/clock/exynos5250.h +++
> >> b/include/dt-bindings/clock/exynos5250.h @@ -21,6 +21,7 @@
> >> #define CLK_FOUT_CPLL 6
> >> #define CLK_FOUT_EPLL 7
> >> #define CLK_FOUT_VPLL 8
> >> +#define CLK_ARM_CLK 12
> >>
> >> /* gate for special clocks (sclk) */
> >> #define CLK_SCLK_CAM_BAYER 128
> >
> >
> >
> > --
> > Best regards,
> >
> > Lukasz Majewski
> >
> > Samsung R&D Institute Poland (SRPOL) | Linux Platform Group
>
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--
Best regards,

Lukasz Majewski

Samsung R&D Institute Poland (SRPOL) | Linux Platform Group