Re: [PATCH] dmaengine: shdma: use normal interface for passing slave id

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Morimoto-san,

On Tuesday 20 January 2015 00:37:04 Kuninori Morimoto wrote:
> Hi Laurent
> 
> >> The shmobile platform is one of only two users of the slave_id field
> >> in dma_slave_config, which is incompatible with the way that the
> >> dmaengine API normally works.
> >> 
> >> I've had a closer look at the existing code now and found that all
> >> slave drivers that pass a slave_id in dma_slave_config for SH do that
> >> right after passing the same ID into shdma_chan_filter, so we can just
> >> rely on that. However, the various shdma drivers currently do not
> >> remember the slave ID that was passed into the filter function when
> >> used in non-DT mode and only check the value to find a matching channel,
> >> unlike all other drivers.
> >> 
> >> There might still be drivers that are not part of the kernel that rely
> >> on setting the slave_id to some other value, so to be on the safe side,
> >> this adds another 'real_slave_id' field to shdma_chan that remembers
> >> the ID and uses it when a driver passes a zero slave_id in
> >> dma_slave_config, like most drivers do.
> >> 
> >> Eventually, the real_slave_id and slave_id fields should just get merged
> >> into one field, but that requires other changes.
> > 
> > Morimoto-san, do you think we need to care about out-of-tree drivers here,
> > or could we merge slave_id and real_slave_id already ?
> 
> Sorry, what does your "out-of-tree" mean ?

That's the drivers that are not part of the kernel that Arnd mentioned in this 
commit message.

> > >  drivers/dma/sh/shdma-base.c       |   72 +++++++++++++++++++++---------
> > >  drivers/mmc/host/sh_mmcif.c       |   12 +++----
> > >  drivers/mmc/host/sh_mobile_sdhi.c |    2 --
> > >  drivers/mmc/host/tmio_mmc.h       |    2 --
> > >  drivers/mmc/host/tmio_mmc_dma.c   |    4 ---
> > >  drivers/mtd/nand/sh_flctl.c       |    2 --
> > >  drivers/spi/spi-rspi.c            |    1 -
> > >  drivers/spi/spi-sh-msiof.c        |    1 -
> > >  include/linux/shdma-base.h        |    1 +
> > 
> > This might need to be split into different patches to avoid conflicts when
> > merging.
> 
> OK, will try in v2

If you can get the various maintainers involved in this to agree on a single 
tree through which to merge the patch there will be no need to split it, but 
as 3 subsystems are involved it might be difficult to avoid merge conflicts.

-- 
Regards,

Laurent Pinchart