Re: [PATCH v3] ARM: omap: edma: add suspend suspend/resume hooks

[Gururaja Hebbar <gururaja.hebbar@ti.com>]

On Wednesday 09 October 2013 11:33 AM, Fernandes, Joel wrote:
> Some temporary issues with my mua so forgive any artifacts in this email.
> 
> On Oct 9, 2013, at 12:14 AM, "Hebbar, Gururaja" <gururaja.hebbar@ti.com> wrote:
> 
>> On Wednesday 09 October 2013 09:58 AM, Joel Fernandes wrote:
>>> On 10/01/2013 10:04 AM, Daniel Mack wrote:
>>>> This patch makes the edma driver resume correctly after suspend. Tested
>>>> on an AM33xx platform with cyclic audio streams.
>>>>
>>>> The code was shamelessly taken from an ancient BSP tree.
>>>>
>>>> Signed-off-by: Daniel Mack <zonque@gmail.com>
>>>> ---
>>>> arch/arm/common/edma.c | 133 +++++++++++++++++++++++++++++++++++++++++++++++++
>>>> 1 file changed, 133 insertions(+)
>>
>> ..snip..
>> ..snip..
>>>
>>>> +        edma_cc[j]->context.ch_map =
>>>> +            kzalloc((sizeof(unsigned int) *
>>>> +                 edma_cc[j]->num_channels), GFP_KERNEL);
>>>> +        edma_cc[j]->context.que_num =
>>>> +            kzalloc((sizeof(unsigned int) * 8), GFP_KERNEL);
>>>
>>> Can these allocations be moved to the suspend path? For systems that don't
>>> suspend/resume even once, I feel we shouldn't allocate memory that we don't use.
>>> These allocations are better to do there.
>>
>> AFAIK, Suspend/resume should be quick. Allocating and deallocating on
>> every iterating would be useless and time consuming.
> 
> Nobody said allocate and deallocate on every iteration. Allocate once during the first suspend call and then don't have to allocate on subsequent calls.

I couldn't find any code which allocates parameters inside suspend.
Could you show me some code which does this?

> 
> As for suspend resume being quick, that argument can flipped the other way too, booting should be quick which is far more frequent than suspend/resume. Apart from the fact that we're not allocating useless memory we would never use.
> 
>>
>> Also this task is one time and quick.
> 
> Exactly.

i was referring to allocating in probe call..

> 
>>
>> Are there any systems (Linux based for now) which doesn't
>> suspend/resume? I believe the probability is very less.
> 
> Nobody talked about suspend/resume not being supported in Linux so not sure what your argument is here.

I meant linux systems which doesn't go to suspend and resume. Not
suspend/resume feature.

Also, I was referring to your 1st comment "... For systems that don't
suspend/resume even once, ...."


regards
Gururaja

> 
> regards,
> 
> -Joel
> 
>>
>> regards
>> Gururaja
>>
>>>
>>> -Joel
>>>
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>>