[U-Boot] [PATCH] drivers: MMC: initialize MMC devices using the device model

[Sjoerd Simons]

On Sun, 2015-08-23 at 15:22 -0600, Simon Glass wrote:
> Hi Andre,
> 
> On 28 July 2015 at 11:19, Andre Przywara <andre.przywara at arm.com> 
> wrote:
> > So far every MMC driver is relying on a board specific init 
> > routine,
> > but as the Rockchip MMC driver is the first MMC device model user,
> > it requires a generic DM MMC init routine.
> > 
> > Add that to the MMC init path to enable the Rockchip driver.
> > 
> > Signed-off-by: Andre Przywara <andre.przywara at arm.com>
> > ---
> > Hi Simon,
> > 
> > this goes on top of your rockchip-working branch in the u-boot-dm
> > repo.
> > Not fully satisfied with this one, but the best I could come up 
> > with
> > without reading the whole of the device model code ;-)
> > This makes the SD card visible to U-Boot on my RK3288 dev board, I
> > can see partitions and load files from it. It gives me information
> > about the eMMC as well, but I haven't tested this so far except for
> > that mmc info.
> > 
> > Cheers,
> > Andre.
> > 
> >  drivers/mmc/mmc.c | 9 ++++++++-
> >  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> Thanks for the patch and sorry for ignoring it so long. I'm finally
> getting close to getting the rockchip patches applied.
> 
> See also this one:
> 
> http://patchwork.ozlabs.org/patch/507840/

As the author of that one, i missed this one :/

> > 
> > diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
> > index da47037..52e82b5 100644
> > --- a/drivers/mmc/mmc.c
> > +++ b/drivers/mmc/mmc.c
> > @@ -17,6 +17,7 @@
> >  #include <linux/list.h>
> >  #include <div64.h>
> >  #include "mmc_private.h"
> > +#include <dm.h>
> > 
> >  static struct list_head mmc_devices;
> >  static int cur_dev_num = -1;
> > @@ -1765,7 +1766,13 @@ int mmc_initialize(bd_t *bis)
> >         INIT_LIST_HEAD (&mmc_devices);
> >         cur_dev_num = 0;
> > 
> > -#ifndef CONFIG_DM_MMC
> > +#ifdef CONFIG_DM_MMC
> > +       struct udevice *udev;
> > +
> > +       for (;;cur_dev_num++)
> > +               if (uclass_get_device(UCLASS_MMC, cur_dev_num, 
> > &udev))
> > +                       break;
> 
> Do you have to increase cur_dev_num? I thought it might happen
> automatically when a device is probed and calls mmc_create().

Yes mmc_create increases it so this way is buggy.. I think my patch is
nicer here wrt. using uclass_foreach_device. Also i was under the
impression that in principle there could be gaps in the device numbers
in DM ? (maybe thats not the case for the MMC ones though)

> Do you think it would work if instead we changed get_mmc_num() to do 
> this?

> With driver model we are trying to make it so that devices a probed
> when they are used, not before. I.e. mmc_initialize() should ideally
> be a nop.

The key here is that functions like print_mmc_devices and
find_mmc_device simply iterate the mmc_devices list, so i don't think
you can key on get_mmc_num at the moment.

Ofcourse a nicer long-term solution would be to make those functions be
DM aware so that the mmc_devices list can disappear, but either this
patch or mine seems like a reasonable first small step :)

> > +#else
> >         if (board_mmc_init(bis) < 0)
> >                 cpu_mmc_init(bis);
> >  #endif
> > --
> > 2.3.5
> > 
> 
> Regards,
> Simon
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-- 
Sjoerd Simons <sjoerd.simons at collabora.co.uk>
Collabora Ltd.