[PATCH v5 1/4] genalloc: add a global pool list, allow to find pools by phys address

[Paul Gortmaker]

On Thu, Nov 15, 2012 at 8:25 AM, Philipp Zabel <p.zabel at pengutronix.de>wrote:

> Hi Paul,
>
> Am Freitag, den 26.10.2012, 15:46 -0400 schrieb Paul Gortmaker:
> > On Thu, Oct 18, 2012 at 10:27 AM, Philipp Zabel <p.zabel at pengutronix.de>
> wrote:
> > > This patch keeps all created pools in a global list and adds two
> > > functions that allow to retrieve the gen_pool pointer from a known
> > > physical address and from a device tree node.
> >
> > So, I'm not seeing any added users of the of_get_named_gen_pool,
> > or the other exported "reverse-lookup" function.  Without that, the
> > anticipated use case is not clear to me.
>
> My use case is the coda video codec driver, for a video codec IP core
> that is integrated in various SoCs. It can use on-SoC SRAM as temporary

memory.
>

Thanks Philipp,

So perhaps it makes sense to somehow tie this patch to the user
patch, since from what I recall reading in the past, the infrastructure
additions that are immediately used are far more favourably rec'd
than those that are weakly bound to a hand-wavey possibly vapour
ware like use case that may or may not materialize going forward.

Paul.
--



>
> Other possible use cases are the TI Davinci sound driver.
> Or the PXA frame buffer driver could allocate a frame buffer in SRAM for
> low-resolution devices.
>
> > Is there an example of some pending driver or similar, that has
> > a phys addr from an unknown source and needs to know what
> > pool it may or may not be in?  With the use case, someone might
> > be able to suggest alternative ways to get what you want done.
>
> drivers/media/platform/coda.c right now uses imx specific
> iram_alloc/free wrappers around gen_pool_alloc/free.
> I'd like to use of_get_named_gen_pool to obtain the struct gen_pool
> pointer and use gen_pool_alloc/free directly, instead.
>
> sound/soc/davinci/davinci-pcm.c right now uses davinci specific
> sram_alloc/free wrappers around gen_pool_alloc/free.
>
> drivers/dma/mmp_tdma.c and sound/soc/pxa/mmp-pcm.c already use
> gen_pool_alloc/free directly, but they use a arch-mmp specific
> sram_get_gpool function to obtain the struct gen_pool pointer.
>
> > It might also be worth cross compiling this for powerpc, since the
> > header files you implicitly get included varies from one arch to
> > the next, and there might be some compile fails lurking there.
>
> Thanks, I'll do that.
>
> regards
> Philipp
>
>
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