Re: [PATCH v2] OMAP3: PM: ensure IO wakeups are properly disabled

[Ameya Palande <ameya.palande@nokia.com>]

Hi Kevin,

On Wed, 2010-08-11 at 18:03 +0200, ext Kevin Hilman wrote:
> From: Kevin Hilman <khilman@ti.com>
> 
> Commit 5a5f561 (convert OMAP3 PRCM macros to the _SHIFT/_MASK suffixes)
> mistakenly removed the check for PER when disabling the IO chain.
> 
> During idle, if the PER powerdomain transitions and CORE does not (as
> is the case with the lower C-states when using CPUidle) the IO pad
> wakeups are not being disabled in the idle path after they are
> enabled.
> 
> This patch ensures that the check for disabling IO wakeups also checks
> for PER transitions, matching the check done to enable IO wakeups.
> 
> Found when debugging PM/CPUidle related problems reported by Ameya
> Palande <ameya.palande@nokia.com>.  Problems were triggered
> particularily on boards with UART2 consoles (n900, Overo) since UART2
> is in the PER powerdomain.
> 
> Tested on l-o master (omap3_defonfig + CONFIG_CPU_IDLE=y) as well
> as with current PM branch.  Boards tested: n900, Overo, omap3evm.
> 
> Cc: Paul Walmsley <paul@pwsan.com>
> Cc: Ameya Palande <ameya.palande@nokia.com>
> Tested-by: Jarkko Nikula <jhnikula@gmail.com>
> Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
> ---
> Tony, this should go in with fixes for -rc2
> 
> Changes since v1
> - added a bit of history about where the problem was created
> - added 'Tested-by' for Jarkko
> 
>  arch/arm/mach-omap2/pm34xx.c |    4 +++-
>  1 files changed, 3 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
> index fb4994a..7b03426 100644
> --- a/arch/arm/mach-omap2/pm34xx.c
> +++ b/arch/arm/mach-omap2/pm34xx.c
> @@ -480,7 +480,9 @@ void omap_sram_idle(void)
>  	}
>  
>  	/* Disable IO-PAD and IO-CHAIN wakeup */
> -	if (omap3_has_io_wakeup() && core_next_state < PWRDM_POWER_ON) {
> +	if (omap3_has_io_wakeup() &&
> +	    (per_next_state < PWRDM_POWER_ON ||
> +	     core_next_state < PWRDM_POWER_ON)) {
>  		prm_clear_mod_reg_bits(OMAP3430_EN_IO_MASK, WKUP_MOD, PM_WKEN);
>  		omap3_disable_io_chain();
>  	}

Thanks for your fix!
I tried out following patch on n900 kernel (based on 2.6.35 mainline)
hosted at: http://gitorious.org/nokia-n900-kernel

Patch:

diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
index b88737f..887242d 100644
--- a/arch/arm/mach-omap2/pm34xx.c
+++ b/arch/arm/mach-omap2/pm34xx.c
@@ -479,7 +479,8 @@ void omap_sram_idle(void)
        }
 
        /* Disable IO-PAD and IO-CHAIN wakeup */
-       if (core_next_state < PWRDM_POWER_ON) {
+       if (per_next_state < PWRDM_POWER_ON ||
+                       core_next_state < PWRDM_POWER_ON) {
                prm_clear_mod_reg_bits(OMAP3430_EN_IO_MASK, WKUP_MOD,
PM_WKEN);
                omap3_disable_io_chain();
        }

And got following WARNING after sometime:

[  109.394714] ------------[ cut here ]------------
[  109.399414] WARNING: at arch/arm/mach-omap2/pm34xx.c:292
prcm_interrupt_handler+0xb4/0x108()
[  109.407897] prcm: WARNING: PRCM indicated MPU wakeup but no wakeup
sources are marked
[  109.415771] Modules linked in: sco bnep l2cap bluetooth ipv6
wl1251_spi wl1251 omaplfb pvrsrvkm cmt_speech mac80211 ssi_protocol hsi_
char cmt omap_ssi crc7 g_ether tsl2563(C) industrialio(C) rtc_twl
rtc_core twl4030_pwrbutton gpio_keys
[  109.437042] [<c0039a54>] (unwind_backtrace+0x0/0x168) from
[<c005ecdc>] (warn_slowpath_common+0x4c/0x64)
[  109.446594] [<c005ecdc>] (warn_slowpath_common+0x4c/0x64) from
[<c005ed74>] (warn_slowpath_fmt+0x2c/0x3c)
[  109.456237] [<c005ed74>] (warn_slowpath_fmt+0x2c/0x3c) from
[<c0043860>] (prcm_interrupt_handler+0xb4/0x108)
[  109.466125] [<c0043860>] (prcm_interrupt_handler+0xb4/0x108) from
[<c008dcc0>] (handle_IRQ_event+0x24/0xe0)
[  109.475952] [<c008dcc0>] (handle_IRQ_event+0x24/0xe0) from
[<c008fe00>] (handle_level_irq+0xd4/0x180)
[  109.485260] [<c008fe00>] (handle_level_irq+0xd4/0x180) from
[<c003406c>] (asm_do_IRQ+0x6c/0x8c)
[  109.494018] [<c003406c>] (asm_do_IRQ+0x6c/0x8c) from [<c0034ac8>]
(__irq_svc+0x48/0xa8)
[  109.502075] Exception stack(0xc0481eb0 to 0xc0481ef8)
[  109.507141] 1ea0:                                     00000020
c04866f0 c0480000 c04db080
[  109.515380] 1ec0: c0480000 00000202 00000000 00000002 0000000a
c0480000 c04db080 00000000
[  109.523620] 1ee0: 00000002 c0481ef8 c00642c8 c00641c8 20000113
ffffffff
[  109.530303] [<c0034ac8>] (__irq_svc+0x48/0xa8) from [<c00641c8>]
(__do_softirq+0x3c/0xf8)
[  109.538543] [<c00641c8>] (__do_softirq+0x3c/0xf8) from [<c00642c8>]
(irq_exit+0x44/0xa8)
[  109.546691] [<c00642c8>] (irq_exit+0x44/0xa8) from [<c0034070>]
(asm_do_IRQ+0x70/0x8c)
[  109.554656] [<c0034070>] (asm_do_IRQ+0x70/0x8c) from [<c0034ac8>]
(__irq_svc+0x48/0xa8)
[  109.562713] Exception stack(0xc0481f38 to 0xc0481f80)
[  109.567810] 1f20:
0028f9f0 00000000
[  109.576049] 1f40: 0028f9f0 00000000 c04ba290 c04ba274 00000003
00000003 8002b868 411fc083
[  109.584259] 1f60: 0000001f 00000000 00000000 c0481f80 c00449a4
c00449b0 60000013 ffffffff
[  109.592498] [<c0034ac8>] (__irq_svc+0x48/0xa8) from [<c00449b0>]
(omap3_enter_idle+0x104/0x134)
[  109.601287] [<c00449b0>] (omap3_enter_idle+0x104/0x134) from
[<c02acb24>] (cpuidle_idle_call+0xa0/0x108)
[  109.610839] [<c02acb24>] (cpuidle_idle_call+0xa0/0x108) from
[<c0035f20>] (cpu_idle+0x48/0xa0)
[  109.619506] [<c0035f20>] (cpu_idle+0x48/0xa0) from [<c0008974>]
(start_kernel+0x278/0x2d8)
[  109.627838] [<c0008974>] (start_kernel+0x278/0x2d8) from [<80008034>]
(0x80008034)
[  109.635467] ---[ end trace 89613c3938486d08 ]---

I got several such warnings multiple time once I keep N900 idle.

Cheers,
Ameya.