[PATCH] S5PV210 Correct clock register properties
Kyungmin Park
kmpark at infradead.org
Thu Jun 17 19:40:10 EDT 2010
Acked-by: Kyungmin Park <kyungmin.park at samsung.com>
To Ben,
My concern is happen. that's reason to use the macro instead of
hard-coded values.
It's need to merge 2.6.35-rc4.
Thank you,
Kyungmin Park
On Thu, Jun 17, 2010 at 5:33 PM, MyungJoo Ham <myungjoo.ham at samsung.com> wrote:
> From: MyungJoo Ham <myungJoo.ham at samsung.com>
>
> Corrected shift values of I2S and UART clocks (CLK_GATE_IP3).
>
> I2S (CLK_GATE_IP3) and UART (CLK_GATE_IP3) had wrong register shift
> values, which in turn, made them turn on and off wrong clocks.
>
> Please note that each clock definition should access different control
> register; otherwise, the system may suffer lockups. For example, if we
> have two clock definitions "a" and "b" which access the same register
> (and the shift value). Then, when we do:
>
> module B
> 1 clk = clk_get("b");
> 2 clk->clk_enable(clk);
> 3 do something with clk.
> 4 clk->clk_disable(clk);
>
> module A
> 1 clk = clk_get("a");
> 2 clk->clk_enable(clk);
> 3 do something with clk
> 4 clk->clk_disable(clk);
>
> And if the execution order is
>
> B1->B2->A1->A2->A3->A4->B3 ...
>
> Then, the system may hang at the point B3.
>
>
> Therefore, there should be no clock definitions with the same contol
> register/shift. If we need to create "aliases", then, creating child
> clocks sharing the clock should be fine.
>
> However, we did not mitigate this doppelganger clock problem for "struct
> clksrc_clk" vs "struct clk"; look at "hsmmc" vs "mmc_bus". In the next
> patch, we plan to let "struct clksrc_clk" access "CLK_SRC_MASK0" and
> "CLK_SRC_MASK1"; i.e., clock source enable/disable should mask the clock
> source itself, not the clock that is supplied by the clock source.
>
> Signed-off-by: MyungJoo Ham <myungjoo.ham at samsung.com>
> ---
> arch/arm/mach-s5pv210/clock.c | 12 ++++++------
> 1 files changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/arch/arm/mach-s5pv210/clock.c b/arch/arm/mach-s5pv210/clock.c
> index 154bca4..ec5ad8c 100644
> --- a/arch/arm/mach-s5pv210/clock.c
> +++ b/arch/arm/mach-s5pv210/clock.c
> @@ -406,13 +406,13 @@ static struct clk init_clocks_disable[] = {
> .id = 0,
> .parent = &clk_p,
> .enable = s5pv210_clk_ip3_ctrl,
> - .ctrlbit = (1<<4),
> + .ctrlbit = (1<<5),
> }, {
> .name = "i2s_v32",
> .id = 1,
> .parent = &clk_p,
> .enable = s5pv210_clk_ip3_ctrl,
> - .ctrlbit = (1<<4),
> + .ctrlbit = (1<<6),
> }
> };
>
> @@ -429,25 +429,25 @@ static struct clk init_clocks[] = {
> .id = 0,
> .parent = &clk_pclk_psys.clk,
> .enable = s5pv210_clk_ip3_ctrl,
> - .ctrlbit = (1<<7),
> + .ctrlbit = (1<<17),
> }, {
> .name = "uart",
> .id = 1,
> .parent = &clk_pclk_psys.clk,
> .enable = s5pv210_clk_ip3_ctrl,
> - .ctrlbit = (1<<8),
> + .ctrlbit = (1<<18),
> }, {
> .name = "uart",
> .id = 2,
> .parent = &clk_pclk_psys.clk,
> .enable = s5pv210_clk_ip3_ctrl,
> - .ctrlbit = (1<<9),
> + .ctrlbit = (1<<19),
> }, {
> .name = "uart",
> .id = 3,
> .parent = &clk_pclk_psys.clk,
> .enable = s5pv210_clk_ip3_ctrl,
> - .ctrlbit = (1<<10),
> + .ctrlbit = (1<<20),
> },
> };
>
> --
> 1.6.3.3
>
>
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