Re: OMAP HSMMC problems with off-mode

[Kevin Hilman <khilman@deeprootsystems.com>]

Paul Walmsley <paul@pwsan.com> writes:

> Hi,
>
> On Tue, 7 Dec 2010, Chikkature Rajashekar, Madhusudhan wrote:
>
>> On Tue, Dec 7, 2010 at 1:51 PM, Adrian Hunter <adrian.hunter@nokia.com> wrote:
>> >
>> > It is at least because omap_pm_get_dev_context_loss_count() is not
>> > implemented.  Tero Kristo was looking at that recently.
>> >
>> 
>> Yes. I agree that is the problem. In the .32 kernel I had hooked it to
>> "get_last_off_on_transaction_id" which helped.
>> But that functionality does not exist anymore. So something equivalent
>> to tell the driver when the OFF was hit will make it work.
>
> OK, let's see if we can get that fixed in at least some trivial 
> way for 2.6.38.  While working on this, I applied this trivial patch:
>
> diff --git a/arch/arm/plat-omap/omap-pm-noop.c b/arch/arm/plat-omap/omap-pm-noop.c
> index e129ce8..781aa5f 100644
> --- a/arch/arm/plat-omap/omap-pm-noop.c
> +++ b/arch/arm/plat-omap/omap-pm-noop.c
> @@ -30,6 +30,8 @@ struct omap_opp *dsp_opps;
>  struct omap_opp *mpu_opps;
>  struct omap_opp *l3_opps;
>  
> +static int dummy_context_loss_counter;
> +
>  /*
>   * Device-driver-originated constraints (via board-*.c files)
>   */
> @@ -303,7 +305,7 @@ int omap_pm_get_dev_context_loss_count(struct device *dev)
>  	 * off counter.
>  	 */
>  
> -	return 0;
> +	return dummy_context_loss_counter++;
>  }
>  
>  
>
> ... which causes drivers to believe that device context has been lost 
> after each call to omap_pm_get_dev_context_loss_count().  Brutal, but 
> effective for chasing out context save/restore bugs.  

Tested-by: Kevin Hilman <khilman@deeprootsystems.com>

I verified that this, in combination with your other patch[1] results in
working off-suspend with MMC on 34xx/n900, 35xx/beagle and 36xx/zoom3.

Paul, do you want to submit a formal patch for this for 2.6.38? if not,
I can add a changelog and queue this with other PM core changes for 2.6.38.

Kevin

[1] MMC: omap_hsmmc: enable interface clock before calling mmc_host_enable()
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