Re: [PATCH PM-20081106] OMAP3: UART: Make sure that uart clocks are enabled when needed

[Kevin Hilman <khilman@deeprootsystems.com>]

"Sriram V" <vshrirama@gmail.com> writes:

> Hi,
>    I just tried to find the source of the problem with PM-20081106 branch.
>    Am trying to debug this issue now.
>
>
>    I tried to do a check to find which commit caused the problem.
>    I find that it is something to do with uart pm support.
>
>
>   The patch commit 1e274e917472dba6c216b67c3afb3e7abe6e77e4
>    OMAP3: PM: Allow UARTs to be unclocked when inactive
>    introduces this issue.
>

Sriram,

Can you try Jouni's patch at the beginning of this thread on top of
pm-20081106?

Kevin

>
>
>
>
> On Wed, Nov 12, 2008 at 7:10 PM, Sriram V <vshrirama@gmail.com> wrote:
>> Hi jouni,
>> I have disabled all the drivers except i2c and network also.
>> i have applied your patch and still seeing problems.
>>
>> doing a echo mem > /sys/power/state makes the system to hang.
>>
>> does this work for you?
>>
>>
>> Regards,
>> sriram
>>
>>
>> On Wed, Nov 12, 2008 at 7:05 PM, Högander Jouni
>> <jouni.hogander@nokia.com> wrote:
>>> "ext Sriram V" <vshrirama@gmail.com> writes:
>>>
>>>> Hi jouni,
>>>>    Does the branch "PM-20081106" work for you?
>>>>
>>>>    When i try to do a "echo mem > /sys/power/state" on omap3evm.
>>>>
>>>>    the system hangs. Does Suspend-Resume work on this branch?
>>>
>>> Yes, but you need to apply this patch (or something similiar). Have
>>> you done it and still seeing problems?
>>>
>>>>
>>>>
>>>> [root@OMAP3EVM /proc]# echo mem > /sys/power/state
>>>> <6>PM: Syncing filesystems ... PM: Syncing filesystems ... done.
>>>> done.
>>>> Freezing user space processes ... Freezing user space processes ...
>>>> (elapsed 0.00 seconds) (elapsed 0.00 seconds) done.
>>>> done.
>>>> Freezing remaining freezable tasks ... Freezing remaining freezable
>>>> tasks ... (elapsed 0.00 seconds) (elapsed 0.00 seconds) done.done.
>>>>
>>>> Suspending console(s) (use no_console_suspend to debug)
>>>> Suspending console(s) (use no_console_suspend to debug)
>>>>
>>>> ---- system hangs----
>>>>
>>>>
>>>> With Regards,
>>>> Sriram
>>>>
>>>>
>>>>
>>>> On Wed, Nov 12, 2008 at 6:43 PM, Högander Jouni
>>>> <jouni.hogander@nokia.com> wrote:
>>>>> "ext Jouni Hogander" <jouni.hogander@nokia.com> writes:
>>>>>
>>>>>> Current implementation makes it possible that printouts are
>>>>>> written into UART while its clocks are disabled. This causes freeze.
>>>>>
>>>>> Now I got how this new uart clock handling works. Event thought this
>>>>> fix is not too sensible it actually does what is needed.
>>>>>
>>>>> So the problem is that uart clocks are enabled in prcm_interrupt. Now
>>>>> if some other interrupt handler is run before prcm_interrupt_handler
>>>>> and it tries to printout something to uart -> system freezes.
>>>>>
>>>>> Kevin, you should ensure some way that uart clocks are enabled right
>>>>> away after wakeup. This patch presents one possibile
>>>>> implementation. Another way could be to move uart_check_wakeup to be
>>>>> run in idle loop rather than in interrupt handler.
>>>>>
>>>>>>
>>>>>> This patch contains possible fix for this.
>>>>>>
>>>>>> Signed-off-by: Jouni Hogander <jouni.hogander@nokia.com>
>>>>>> ---
>>>>>>  arch/arm/mach-omap2/pm34xx.c             |    6 ++++++
>>>>>>  arch/arm/mach-omap2/serial.c             |   30 ++++++++++++++++++++++++++++++
>>>>>>  arch/arm/plat-omap/include/mach/serial.h |    2 ++
>>>>>>  3 files changed, 38 insertions(+), 0 deletions(-)
>>>>>>
>>>>>> diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
>>>>>> index d480c39..3838a19 100644
>>>>>> --- a/arch/arm/mach-omap2/pm34xx.c
>>>>>> +++ b/arch/arm/mach-omap2/pm34xx.c
>>>>>> @@ -320,6 +320,7 @@ void omap_sram_idle(void)
>>>>>>       /* PER */
>>>>>>       per_next_state = pwrdm_read_next_pwrst(per_pwrdm);
>>>>>>       if (per_next_state < PWRDM_POWER_ON) {
>>>>>> +             omap_uart_prepare_idle(2);
>>>>>>               omap2_gpio_prepare_for_retention();
>>>>>>               if (per_next_state == PWRDM_POWER_OFF)
>>>>>>                       omap3_per_save_context();
>>>>>> @@ -328,6 +329,8 @@ void omap_sram_idle(void)
>>>>>>       /* CORE */
>>>>>>       core_next_state = pwrdm_read_next_pwrst(core_pwrdm);
>>>>>>       if (core_next_state < PWRDM_POWER_ON) {
>>>>>> +             omap_uart_prepare_idle(0);
>>>>>> +             omap_uart_prepare_idle(1);
>>>>>>               if (core_next_state == PWRDM_POWER_OFF) {
>>>>>>                       prm_set_mod_reg_bits(OMAP3430_AUTO_OFF,
>>>>>>                                            OMAP3430_GR_MOD,
>>>>>> @@ -386,6 +389,8 @@ void omap_sram_idle(void)
>>>>>>                       prm_clear_mod_reg_bits(OMAP3430_AUTO_OFF,
>>>>>>                                              OMAP3430_GR_MOD,
>>>>>>                                              OMAP3_PRM_VOLTCTRL_OFFSET);
>>>>>> +             omap_uart_resume_idle(0);
>>>>>> +             omap_uart_resume_idle(1);
>>>>>>       }
>>>>>>
>>>>>>       /* PER */
>>>>>> @@ -394,6 +399,7 @@ void omap_sram_idle(void)
>>>>>>               if (per_prev_state == PWRDM_POWER_OFF)
>>>>>>                       omap3_per_restore_context();
>>>>>>               omap2_gpio_resume_after_retention();
>>>>>> +             omap_uart_resume_idle(2);
>>>>>>       }
>>>>>>
>>>>>>       /* Enable smartreflex after WFI */
>>>>>> diff --git a/arch/arm/mach-omap2/serial.c b/arch/arm/mach-omap2/serial.c
>>>>>> index 65cce87..ef30d8d 100644
>>>>>> --- a/arch/arm/mach-omap2/serial.c
>>>>>> +++ b/arch/arm/mach-omap2/serial.c
>>>>>> @@ -249,6 +249,36 @@ static void omap_uart_idle_timer(unsigned long data)
>>>>>>       omap_uart_allow_sleep(uart);
>>>>>>  }
>>>>>>
>>>>>> +void omap_uart_prepare_idle(int num)
>>>>>> +{
>>>>>> +     struct omap_uart_state *uart;
>>>>>> +
>>>>>> +     if (!clocks_off_while_idle)
>>>>>> +             return;
>>>>>> +
>>>>>> +     list_for_each_entry(uart, &uart_list, node) {
>>>>>> +             if (num == uart->num && uart->can_sleep) {
>>>>>> +                     omap_uart_disable_clocks(uart);
>>>>>> +                     return;
>>>>>> +             }
>>>>>> +     }
>>>>>> +}
>>>>>> +
>>>>>> +void omap_uart_resume_idle(int num)
>>>>>> +{
>>>>>> +     struct omap_uart_state *uart;
>>>>>> +
>>>>>> +     if (!clocks_off_while_idle)
>>>>>> +             return;
>>>>>> +
>>>>>> +     list_for_each_entry(uart, &uart_list, node) {
>>>>>> +             if (num == uart->num) {
>>>>>> +                     omap_uart_enable_clocks(uart);
>>>>>> +                     return;
>>>>>> +             }
>>>>>> +     }
>>>>>> +}
>>>>>> +
>>>>>>  void omap_uart_check_wakeup(void)
>>>>>>  {
>>>>>>       struct omap_uart_state *uart;
>>>>>> diff --git a/arch/arm/plat-omap/include/mach/serial.h b/arch/arm/plat-omap/include/mach/serial.h
>>>>>> index 11ff540..254a775 100644
>>>>>> --- a/arch/arm/plat-omap/include/mach/serial.h
>>>>>> +++ b/arch/arm/plat-omap/include/mach/serial.h
>>>>>> @@ -44,6 +44,8 @@
>>>>>>  extern void omap_serial_init(void);
>>>>>>  extern int omap_uart_can_sleep(void);
>>>>>>  extern void omap_uart_check_wakeup(void);
>>>>>> +extern void omap_uart_prepare_idle(int num);
>>>>>> +extern void omap_uart_resume_idle(int num);
>>>>>>  #endif
>>>>>>
>>>>>>  #endif
>>>>>> --
>>>>>> 1.6.0.1
>>>>>>
>>>>>> --
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>>>>>
>>>>> --
>>>>> Jouni Högander
>>>>>
>>>>> --
>>>>> To unsubscribe from this list: send the line "unsubscribe linux-omap" in
>>>>> the body of a message to majordomo@vger.kernel.org
>>>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>>>>
>>>
>>> --
>>> Jouni Högander
>>>
>>>
>>
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