Re: [PATCH v3] OMAP2+: PM: omap device: API's for handling mstandby mode

["G, Manjunath Kondaiah" <manjugk@ti.com>]

On Thu, Nov 18, 2010 at 04:21:48PM +0530, G, Manjunath Kondaiah wrote:
> Certain errata's in OMAP2+ processors will require forcing
> master standby to "no standby" mode before completing on going
> operation. Without this, the results will be unpredictable.
> 
> Since current implementation of PM run time framework does not support
> changing sysconfig settings during middle of the on going operation,
> these API's will support the same. One API will force the device's
> sysconfig mstandby mode settings to "no standby" and other API will
> releases "no standby" mode and sets it to "smart standby" or "no
> standby˝ depending on HWMOD_SWSUP_MSTANDBY value.
> 
> These API's should be used by device drivers only incase of
> erratum applicable to their modules if there is no other methods
> to resolve.
> 
> These API's are required for multiple DMA errata's which require
> putting DMA controller in no mstandby mode before stopping dma.
> 
> The applicable errata's:
> 1. Errata ID: i557(Applicable for omap36xx all ES versions)
> The channel hangs when the Pause bit (DMA4_CDPi [7] ) is cleared
> through config port while in Standby.
> 
> 2. Errata ID: i541(all omap2plus except omap4)
> sDMA FIFO draining does not finish
> 
> 3. OMAP3430 ES1.0(Errata ID:i88) will require DMA to be put in
> no mstandby mode before disabling the channel after completing
> the data transfer operation.
> 
> Also fixes typo HWMOD_SWSUP_MSTDBY to HWMOD_SWSUP_MSTANDBY in
> omap_hwmod.h
> 
> Signed-off-by: G, Manjunath Kondaiah <manjugk@ti.com>
> Cc: Kevin Hilman <khilman@deeprootsystems.com>
> Cc: Paul Walmsley <paul@pwsan.com>
> Cc: linux-arm-kernel@lists.infradead.org
> ---
> Change summary:
> v2: Review comments incorporated for:
> https://patchwork.kernel.org/patch/282212/
> 
>  arch/arm/mach-omap2/omap_hwmod.c              |   45 +++++++++++++++-
>  arch/arm/plat-omap/include/plat/omap_device.h |    3 +-
>  arch/arm/plat-omap/include/plat/omap_hwmod.h  |    4 +-
>  arch/arm/plat-omap/omap_device.c              |   73 +++++++++++++++++++++++++
>  4 files changed, 122 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm/mach-omap2/omap_hwmod.c b/arch/arm/mach-omap2/omap_hwmod.c
> index 5a30658..9c1c2fc 100644
> --- a/arch/arm/mach-omap2/omap_hwmod.c
> +++ b/arch/arm/mach-omap2/omap_hwmod.c
> @@ -1427,6 +1427,50 @@ int omap_hwmod_set_slave_idlemode(struct omap_hwmod *oh, u8 idlemode)
>  }
>  
>  /**
> + * omap_hwmod_set_master_standbymode - set the hwmod's OCP mstandby mode
> + * @oh: struct omap_hwmod *
> + * @midlemode: flag to set mstandby to either "no standby" or "smart standby"
> + *
> + * Sets the IP block's OCP mstandby mode in hardware, and updates our
> + * local copy.  Intended to be used by drivers that have some erratum
> + * that requires direct manipulation of the MIDLEMODE bits.  Returns
> + * -EINVAL if @oh is null, or passes along the return value from
> + * _set_master_standbymode().
> + *
> + * Any users of this function should be scrutinized carefully.
> + */
> +int omap_hwmod_set_master_standbymode(struct omap_hwmod *oh, u8 idlemode)
> +{
> +	u32 v;
> +	u8 sf;
> +	int retval = 0;
> +
> +	if (!oh)
> +		return -EINVAL;
> +
> +	v = oh->_sysc_cache;
> +
> +	if (!oh->class->sysc)
> +		return -EINVAL;
> +

Sorry. I forgot to take mutex here. I will add this change and repost
this patch.

-Manjunath

[...]
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