[PATCH] OMAP2+: PM/serial: fix console semaphore acquire during suspend

[Jean Pihet]

On Tue, Dec 7, 2010 at 9:50 PM, Kevin Hilman
<khilman at deeprootsystems.com> wrote:
> commit 0d8e2d0dad98a693bad88aea6876ac8b94ad95c6 (OMAP2+: PM/serial:
> hold console semaphore while OMAP UARTs are disabled) added use of the
> console semaphore to protect UARTs from being accessed after disabled
> during idle, but this causes problems in suspend.
>
> During suspend, the console semaphore is already held by the time we reach
> the OMAP suspend path, so the try_acquire_console_sem() will always fail and
> suspend will be aborted.
>
> To fix, introduce a check so the console semaphore is only attempted
> during idle, and not during suspend.
>
> Cc: Paul Walmsley <paul at pwsan.com>
> Signed-off-by: Kevin Hilman <khilman at deeprootsystems.com>

Tested OK on Beagleboard with suspend and idle with RET and OFF modes

Tested-by: Jean Pihet <j-pihet at ti.com>

Thanks,
Jean

> ---
> Applies to Tony's omap-fixes branch.
>
>  arch/arm/mach-omap2/pm34xx.c |   24 ++++++++++++++++++------
>  1 files changed, 18 insertions(+), 6 deletions(-)
>
> diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
> index 0ec8a04..122ef3c 100644
> --- a/arch/arm/mach-omap2/pm34xx.c
> +++ b/arch/arm/mach-omap2/pm34xx.c
> @@ -50,6 +50,19 @@
>  #include "sdrc.h"
>  #include "control.h"
>
> +#ifdef CONFIG_SUSPEND
> +static suspend_state_t suspend_state = PM_SUSPEND_ON;
> +static inline bool is_suspending(void)
> +{
> +       return (suspend_state != PM_SUSPEND_ON);
> +}
> +#else
> +static inline bool is_suspending(void)
> +{
> +       return false;
> +}
> +#endif
> +
>  /* Scratchpad offsets */
>  #define OMAP343X_TABLE_ADDRESS_OFFSET     0xc4
>  #define OMAP343X_TABLE_VALUE_OFFSET       0xc0
> @@ -387,10 +400,11 @@ void omap_sram_idle(void)
>        }
>
>        /* Block console output in case it is on one of the OMAP UARTs */
> -       if (per_next_state < PWRDM_POWER_ON ||
> -           core_next_state < PWRDM_POWER_ON)
> -               if (try_acquire_console_sem())
> -                       goto console_still_active;
> +       if (!is_suspending())
> +               if (per_next_state < PWRDM_POWER_ON ||
> +                   core_next_state < PWRDM_POWER_ON)
> +                       if (try_acquire_console_sem())
> +                               goto console_still_active;
>
>        /* PER */
>        if (per_next_state < PWRDM_POWER_ON) {
> @@ -514,8 +528,6 @@ out:
>  }
>
>  #ifdef CONFIG_SUSPEND
> -static suspend_state_t suspend_state;
> -
>  static int omap3_pm_prepare(void)
>  {
>        disable_hlt();
> --
> 1.7.2.1
>
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