[PATCH] ARM: S5PV210: allow clk to use clksrc as parents

[MyungJoo Ham]

Hello,

On Tue, Jul 13, 2010 at 1:21 PM, Kukjin Kim <kgene.kim at samsung.com> wrote:
> MyungJoo Ham wrote:
>>
>
>  (snip)
>
>> >>
>> > Please refer to below diagram.
>> >
>> > ------------------------------------
>> >           dsys bus
>> > ----------------+-------------------
>> >                |
>> >                |1.clk 'lcd'
>> >                |
>> >            +---+-----------+
>> >            |   | FIMD block|
>> >            | +-+           |
>> >            | |             |
>> >            | | |\          |
>> >            | +-|m|         |
>> > 2.SCLK_FIMD |   |u|----+    |
>> > ------------+---|x|    |    |
>> >            |   |/     |    |
>> >            |          |    |
>> >            +----------+----+
>> >                       |
>> > inside of SoC          |
>> > -----------------------+--------------------------
>> > outside of SoC         |
>> >                       | 3.clk?
>> >                       |
>> >               +--------------+
>> >               | LCD module   |
>> >               +--------------+
>> >
>> > In clock.c the clk 'lcd' means #1 in above diagram.
>> > So you mean clk 'lcd' is #3', maybe confused :-(
>> >
>>
>> Uh.. yes, I meant #3 by the clk LCD.
>>
>> This CLK_GATE_IP - FIMD gates both ACLK_FIMD and SCLK_FIMD at the same
>> time; thus, this should be over the MUX of SCLK_FIMD, I thought. (User
>> Manual: Clock Controler - Clock Gating Control Register
>> (CLK_GATE_IP1)) If we should have a struct clk that represents
>> ACLK_FIMD, the clock representing ACLK_FIMD should not directly
>> control CLK_GATE_IP1 as CLK_GATE_IP1 gates SCLK_FIMD as well if the
>> User Manual is correct.
>>
>> If we really need to represent ACLK_FIMD separately, why don't we
>> create "aclk_fimd" and let "fimd" or "lcd" become a struct clksrc_clk
>> that chooses between aclk_fimd and sclk_fimd? How about this? (and
>> other similar clocks)
>>
>> Anyway, with this feature, we may now think about calling
>> "clk_disable(parent)" when a clk is doing
>> "clk_set_parent(another_parent)" if the clk is "clk_enable"d. I'd be
>> happy to hear any suggestions and comments on this.
>
> Basically, each clock which is used in each device driver such as lcd
> module clock, camemra module clock should be controlled in its device
> driver.
>
> Let's say, in the case of camera module clock, FIMC IP has a specific
> divider which is used clock dividing for camera module clock. And the
> divider which is in FIMC IP has own rate for camera module at that time. So
> cannot/no need to define it in the common clock part such as clock.c.
>
> In other words, can't implement set_rate() or get_rate() for camera module
> clock in the common clock part, because FIMC IP block has own specific
> divider for it.
>

Ah... I've got it. Although "lcd" of CLK_GATE_IP contols SCLK_FIMD and
part of HCLK that goes to FIMD at the same time, as long as the MUX of
SCLK_FIMD and that part of HCLK is in VIDCON (VIDCON0:CLKSEL_F), you
don't want the control to be reside in arch/arm/mach side.

I also think let LCD(anyone who's got w/ VIDCON0) driver controls and
owns the MUX info about SCLK_FIMD/HCLK. What I thought once is that
CLK_GATE_IP:CLK_FIMD controls the lcd clock after the MUX as it
controls both ACLK_FIMD(from HCLK) and SCLK_FIMD at the same time.


Thank you.

>>
>> E.g.,
>>
>> struct clk *a = clk_get("A");
>> clk_set_parent(a, clk_A);
>> clk_enable(a);
>> some ops with a;
>> /* we need another clock speed with different source */
>> clk_set_parent(a, clk_B);
>> some ops with b;
>>
>> In this example, we, at least, need to enable clk_B when
>> clk_set_parent is called and we'd better clk_disable(clk_A) if
>> clk_enable(clk_A) is called at clk_enable(a);
>>
>>
>
> Thanks.
>
> Best regards,
> Kgene.
> --
> Kukjin Kim <kgene.kim at samsung.com>, Senior Engineer,
> SW Solution Development Team, Samsung Electronics Co., Ltd.
>
> (snip)
>
>
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>



-- 
MyungJoo Ham (함명주), Ph.D.
Mobile Software Platform Lab,
Digital Media and Communications (DMC) Business
Samsung Electronics
cell: 82-10-6714-2858