[PATCH] SPI: bcm2835: move to the transfer_one driver model

[Mark Brown]

On Fri, Apr 03, 2015 at 12:17:31PM +0200, Martin Sperl wrote:
> > On 01.04.2015, at 17:20, Stephen Warren <swarren at wwwdotorg.org> wrote:

It looks like something rewrote Stephen's message to have no word
wrapping...

> If you read the mmc_spi driver there is a lot of places where we have 
> constructs like this:
>         if (host->dma_dev) {
>                 host->m.is_dma_mapped = 1;
>                 dma_sync_single_for_device(host->dma_dev,
>                                 host->data_dma, sizeof(*host->data),
>                                 DMA_BIDIRECTIONAL);
>         }
>         status = spi_sync_locked(host->spi, &host->m);

We probably need to have a good, hard look at this stuff - in general we
shouldn't be using this sort of mapping in clients, and for some systems
this will actually end up broken.

> Unfortunately I can not test if the the mmc_spi issue exists on a
> beaglebone, as the mmc_spi driver can not even get compiled there because
> of CONFIG_HIGHMEM being set which conflicts with KConfig portion for
> mmc_spi...

This is a bit alarming and probably also indicates that the code needs
looking at.
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