Paul Walmsley <paul@xxxxxxxxx> writes:
> On Sun, 30 Dec 2012, Paul Walmsley wrote:
>
>> There shouldn't be any need to jump to SRAM code if the OMAP CORE
>> clockdomain (and consequently the SDRAM controller and CORE PLL) stays
>> active during MPU WFI. The SRAM code should only be needed when the RAM
>> enters self-refresh. So in the case where CORE stays active, just call
>> WFI directly from the mach-omap2/pm24xx.c code. This removes some
>> unnecessary SRAM code.
>>
>> Signed-off-by: Paul Walmsley <paul@xxxxxxxxx>
>> Cc: Richard Woodruff <r-woodruff2@xxxxxx>
>> Cc: Kevin Hilman <khilman@xxxxxxxxxxxxxxxxxxx>
>
> Here's an updated version of this one.
>
>
> - Paul
>
> From: Paul Walmsley <paul@xxxxxxxxx>
> Date: Sun, 30 Dec 2012 10:15:48 -0700
> Subject: [PATCH] ARM: OMAP2xxx: PM: enter WFI via inline asm if CORE stays
> active
>
> There shouldn't be any need to jump to SRAM code if the OMAP CORE
> clockdomain (and consequently the SDRAM controller and CORE PLL) stays
> active during MPU WFI. The SRAM code should only be needed when the RAM
> enters self-refresh. So in the case where CORE stays active, just call
> WFI directly from the mach-omap2/pm24xx.c code. This removes some
> unnecessary SRAM code.
>
> This second version replaces the inline WFI with the corresponding
> coprocessor register call, using tlbflush.h as an example. This is
> because the assembler doesn't recognize WFI as a valid ARMv6
> instruction.
>
> Signed-off-by: Paul Walmsley <paul@xxxxxxxxx>
> Cc: Richard Woodruff <r-woodruff2@xxxxxx>
> Cc: Kevin Hilman <khilman@xxxxxxxxxxxxxxxxxxx>
Acked-by: Kevin Hilman <khilman@xxxxxxxxxx>
> ---
> arch/arm/mach-omap2/pm24xx.c | 12 ++++++------
> arch/arm/mach-omap2/sleep24xx.S | 19 -------------------
> 2 files changed, 6 insertions(+), 25 deletions(-)
>
> diff --git a/arch/arm/mach-omap2/pm24xx.c b/arch/arm/mach-omap2/pm24xx.c
> index c333fa6..8914b9e 100644
> --- a/arch/arm/mach-omap2/pm24xx.c
> +++ b/arch/arm/mach-omap2/pm24xx.c
> @@ -54,7 +54,6 @@
> #include "powerdomain.h"
> #include "clockdomain.h"
>
> -static void (*omap2_sram_idle)(void);
> static void (*omap2_sram_suspend)(u32 dllctrl, void __iomem *sdrc_dlla_ctrl,
> void __iomem *sdrc_power);
>
> @@ -172,6 +171,8 @@ static int omap2_allow_mpu_retention(void)
>
> static void omap2_enter_mpu_retention(void)
> {
> + const int zero = 0;
> +
> /* Putting MPU into the WFI state while a transfer is active
> * seems to cause the I2C block to timeout. Why? Good question. */
> if (omap2_i2c_active())
> @@ -196,7 +197,8 @@ static void omap2_enter_mpu_retention(void)
> OMAP2_PM_PWSTCTRL);
> }
>
> - omap2_sram_idle();
> + /* WFI */
> + asm("mcr p15, 0, %0, c7, c0, 4" : : "r" (zero) : "memory", "cc");
> }
>
> static int omap2_can_sleep(void)
> @@ -356,11 +358,9 @@ int __init omap2_pm_init(void)
> /*
> * We copy the assembler sleep/wakeup routines to SRAM.
> * These routines need to be in SRAM as that's the only
> - * memory the MPU can see when it wakes up.
> + * memory the MPU can see when it wakes up after the entire
> + * chip enters idle.
> */
> - omap2_sram_idle = omap_sram_push(omap24xx_idle_loop_suspend,
> - omap24xx_idle_loop_suspend_sz);
> -
> omap2_sram_suspend = omap_sram_push(omap24xx_cpu_suspend,
> omap24xx_cpu_suspend_sz);
>
> diff --git a/arch/arm/mach-omap2/sleep24xx.S b/arch/arm/mach-omap2/sleep24xx.S
> index ce0ccd2..1d3cb25 100644
> --- a/arch/arm/mach-omap2/sleep24xx.S
> +++ b/arch/arm/mach-omap2/sleep24xx.S
> @@ -37,25 +37,6 @@
> .text
>
> /*
> - * Forces OMAP into idle state
> - *
> - * omap24xx_idle_loop_suspend() - This bit of code just executes the WFI
> - * for normal idles.
> - *
> - * Note: This code get's copied to internal SRAM at boot. When the OMAP
> - * wakes up it continues execution at the point it went to sleep.
> - */
> - .align 3
> -ENTRY(omap24xx_idle_loop_suspend)
> - stmfd sp!, {r0, lr} @ save registers on stack
> - mov r0, #0 @ clear for mcr setup
> - mcr p15, 0, r0, c7, c0, 4 @ wait for interrupt
> - ldmfd sp!, {r0, pc} @ restore regs and return
> -
> -ENTRY(omap24xx_idle_loop_suspend_sz)
> - .word . - omap24xx_idle_loop_suspend
> -
> -/*
> * omap24xx_cpu_suspend() - Forces OMAP into deep sleep state by completing
> * SDRC shutdown then ARM shutdown. Upon wake MPU is back on so just restore
> * SDRC.
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