Subject: [PATCH 02/10] ARM: OMAP: Fix timer posted mode support

From: [email-masked] (Vaibhav Hiremath)
Date: Thu, 6 Sep 2012 18:27:33 +0530

On 9/6/2012 12:34 AM, Jon Hunter wrote:
> Currently the dmtimer posted mode is being enabled when the function
> __omap_dm_timer_reset() is called. This function is only being called for
> OMAP1 timers and OMAP2+ timers that are being used as system timers. Hence,
> for OMAP2+ timers that are NOT being used as a system timer, posted mode is
> not enabled but the "timer->posted" variable is still set (incorrectly) in
> the omap_dm_timer_prepare() function.
> 
> This is a regression introduced by commit 3392cdd3 (ARM: OMAP: dmtimer:
> switch-over to platform device driver) which changed the code to only call
> omap_dm_timer_reset() for OMAP1 devices. Although this is a regression from
> the original code it only impacts performance and so is not needed for stable.
> 
> Signed-off-by: Jon Hunter <[email-masked]>
> ---
>  arch/arm/mach-omap2/timer.c               |    3 +--
>  arch/arm/plat-omap/dmtimer.c              |   14 +++++---------
>  arch/arm/plat-omap/include/plat/dmtimer.h |    9 ++++++++-
>  3 files changed, 14 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/arm/mach-omap2/timer.c b/arch/arm/mach-omap2/timer.c
> index 5471706..e24ee0f 100644
> --- a/arch/arm/mach-omap2/timer.c
> +++ b/arch/arm/mach-omap2/timer.c
> @@ -194,10 +194,9 @@ static int __init omap_dm_timer_init_one(struct omap_dm_timer *timer,
>  	}
>  	__omap_dm_timer_init_regs(timer);
>  	__omap_dm_timer_reset(timer, 1, 1);
> -	timer->posted = 1;
> +	__omap_dm_timer_enable_posted(timer);
>  
>  	timer->rate = clk_get_rate(timer->fclk);
> -
>  	timer->reserved = 1;
>  
>  	return res;
> diff --git a/arch/arm/plat-omap/dmtimer.c b/arch/arm/plat-omap/dmtimer.c
> index c34f55b..22790ea 100644
> --- a/arch/arm/plat-omap/dmtimer.c
> +++ b/arch/arm/plat-omap/dmtimer.c
> @@ -122,21 +122,15 @@ static void omap_dm_timer_wait_for_reset(struct omap_dm_timer *timer)
>  
>  static void omap_dm_timer_reset(struct omap_dm_timer *timer)
>  {
> -	omap_dm_timer_enable(timer);
>  	if (timer->pdev->id != 1) {
>  		omap_dm_timer_write_reg(timer, OMAP_TIMER_IF_CTRL_REG, 0x06);
>  		omap_dm_timer_wait_for_reset(timer);
>  	}
> -
>  	__omap_dm_timer_reset(timer, 0, 0);
> -	omap_dm_timer_disable(timer);
> -	timer->posted = 1;
>  }
>  
>  int omap_dm_timer_prepare(struct omap_dm_timer *timer)
>  {
> -	int ret;
> -
>  	/*
>  	 * FIXME: OMAP1 devices do not use the clock framework for dmtimers so
>  	 * do not call clk_get() for these devices.
> @@ -150,13 +144,15 @@ int omap_dm_timer_prepare(struct omap_dm_timer *timer)
>  		}
>  	}
>  
> +	omap_dm_timer_enable(timer);
> +
>  	if (timer->capability & OMAP_TIMER_NEEDS_RESET)
>  		omap_dm_timer_reset(timer);
>  
> -	ret = omap_dm_timer_set_source(timer, OMAP_TIMER_SRC_32_KHZ);
> +	__omap_dm_timer_enable_posted(timer);
> +	omap_dm_timer_disable(timer);
>  
> -	timer->posted = 1;
> -	return ret;
> +	return omap_dm_timer_set_source(timer, OMAP_TIMER_SRC_32_KHZ);

May be I am speculating here and I know this is tested and supposed to
work, but Isn't it safe to set parent keeping module enables.

I would still recommend you to move is before omap_dm_timer_disable().
There could be devices or hw bugs/issues, may be related to standby/idle
protocol happening underneath module enable/disable.

Thanks,
Vaibhav
>  }
>  
>  static inline u32 omap_dm_timer_reserved_systimer(int id)
> diff --git a/arch/arm/plat-omap/include/plat/dmtimer.h b/arch/arm/plat-omap/include/plat/dmtimer.h
> index 5ce2f00..fa9d04b 100644
> --- a/arch/arm/plat-omap/include/plat/dmtimer.h
> +++ b/arch/arm/plat-omap/include/plat/dmtimer.h
> @@ -348,13 +348,20 @@ static inline void __omap_dm_timer_reset(struct omap_dm_timer *timer,
>  		l |= 1 << 2;
>  
>  	__raw_writel(l, timer->io_base + OMAP_TIMER_OCP_CFG_OFFSET);
> +}
> +
> +static inline void __omap_dm_timer_enable_posted(struct omap_dm_timer *timer)
> +{
> +	if (timer->posted)
> +		return;
>  
>  	if (timer->errata & OMAP_TIMER_ERRATA_I103_I767)
>  		return;
>  
> -	/* Match hardware reset default of posted mode */
>  	__omap_dm_timer_write(timer, OMAP_TIMER_IF_CTRL_REG,
>  					OMAP_TIMER_CTRL_POSTED, 0);
> +	timer->context.tsicr = OMAP_TIMER_CTRL_POSTED;
> +	timer->posted = 1;
>  }
>  
>  /**
>