Re: [PATCH 3/6] mmc: tmio: convert the SDHI MMC driver from MFD to

[Guennadi Liakhovetski <g.liakhovetski@gmx.de>]

On Sun, 13 Mar 2011, Magnus Damm wrote:

> On Fri, Mar 11, 2011 at 4:52 PM, Guennadi Liakhovetski
> <g.liakhovetski@gmx.de> wrote:
> > On sh-mobile platforms the SDHI driver was using the tmio_mmc SD/SDIO
> > MFD cell driver. Now that the tmio_mmc driver has been split into a
> > core and a separate MFD glue, we can support SDHI natively without the
> > need to emulate an MFD controller. This also allows to support systems
> > with an on-SoC SDHI controller and a separate MFD with a TMIO core.
> >
> > Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
> > ---
> 
> Nice, I believe this is the right direction..
> 
> > --- a/drivers/mmc/host/tmio_mmc.h
> > +++ b/drivers/mmc/host/tmio_mmc.h
> > @@ -92,7 +92,7 @@ struct tmio_mmc_host {
> >        struct tasklet_struct   dma_complete;
> >        struct tasklet_struct   dma_issue;
> >        struct scatterlist      bounce_sg;
> > -#ifdef CONFIG_TMIO_MMC_DMA
> > +#if defined(CONFIG_MMC_SDHI) || defined(CONFIG_MMC_SDHI_MODULE)
> >        u8                      bounce_buf[PAGE_CACHE_SIZE] __attribute__((aligned(TMIO_MAX_ALIGN)));
> >  #else
> >        u8                      bounce_buf[1];  /* A dummy in no-DMA case */
> 
> ... but it would be nice if all this #ifdeffery could be avoided somehow.
> 
> Is it possible to use devres to allocate the bounce buffer dynamically
> in the dma portion of the code?

Well, this #ifdef has been there before, it's not new. But sure, we could 
get rid of it. Basically, what you're suggesting, is to allocate that 
bounce buffer dynamically - whether or not using devres. Just calling 
__get_free_page() in tmio_mmc_request_dma() and __free_pages() in 
tmio_mmc_release_dma() should work without any memory-leaking too. Would 
this be ok?

Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/