Re: [PATCH 1/3] tmio: add a platform flag to disable card

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

On Tue, 11 May 2010, Magnus Damm wrote:

> Hi Guennadi,
> 
> Many thanks for your work on this!
> 
> On Tue, May 11, 2010 at 6:52 PM, Guennadi Liakhovetski
> <g.liakhovetski@gmx.de> wrote:
> > Write-protection status is not always available, e.g., micro-SD cards do not
> > have a write-protection switch at all. This patch adds a flag to let platforms
> > force tmio_mmc to consider the card writable.
> >
> > Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
> > ---
> >  drivers/mmc/host/tmio_mmc.c |    5 ++++-
> >  include/linux/mfd/tmio.h    |    4 ++++
> >  2 files changed, 8 insertions(+), 1 deletions(-)
> >
> > diff --git a/drivers/mmc/host/tmio_mmc.c b/drivers/mmc/host/tmio_mmc.c
> > index 7e79ba4..11c19b0 100644
> > --- a/drivers/mmc/host/tmio_mmc.c
> > +++ b/drivers/mmc/host/tmio_mmc.c
> > @@ -640,8 +640,11 @@ static void tmio_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
> >  static int tmio_mmc_get_ro(struct mmc_host *mmc)
> >  {
> >        struct tmio_mmc_host *host = mmc_priv(mmc);
> > +       struct mfd_cell *cell = host->pdev->dev.platform_data;
> > +       struct tmio_mmc_data *pdata = cell->driver_data;
> >
> > -       return (sd_ctrl_read32(host, CTL_STATUS) & TMIO_STAT_WRPROTECT) ? 0 : 1;
> > +       return ((pdata->flags & TMIO_MMC_WRPROTECT_DISABLE) ||
> > +               (sd_ctrl_read32(host, CTL_STATUS) & TMIO_STAT_WRPROTECT)) ? 0 : 1;
> >  }
> 
> It's a bit late so perhaps I'm thinking backwards, but isn't this
> logic inverted?
> 
> Fact: The WP signal is missing from the micro-sd slot on the kfr2r09
> board, and the card incorrectly comes up write protected.
> 
> Solution: TMIO_MMC_WRPROTECT_DISABLE is set to make sure the card is
> _not_ write protected by mistake.
> 
> But: The code using the ->reg_ro() callback assumes that the card is
> read-only if 1 is returned according to drivers/mmc/core/sd.c. The
> code above returns 1 if TMIO_MMC_WRPROTECT_DISABLE is set. So the card
> will be forced read-only on kfr2r09 unless i'm mistaken, and this does
> not help so much. =)

I think above is right, please, look again. If TMIO_MMC_WRPROTECT_DISABLE 
is set, the function returns 0.

> This seems backwards to me. Can you please double check?

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