Hi,
On Thu, Jan 14, 2016 at 05:25:49PM +0000, Russell King - ARM Linux wrote:
> On Thu, Jan 14, 2016 at 01:07:06PM +0100, Sebastian Reichel wrote:
> > On Thu, Jan 14, 2016 at 02:45:20PM +0530, Kishon Vijay Abraham I wrote:
> > > Since v4.3+, CONFIG_REGULATOR_PBIAS should be enabled (for platforms that
> > > have PBIAS regulator) in order for MMC1 to work.
> > >
> > > Add a more verbose print to help enable CONFIG_REGULATOR_PBIAS for users
> > > using a olddefconfig or a custom .config.
> > >
> > > Signed-off-by: Kishon Vijay Abraham I <kishon@xxxxxx>
> > > ---
> > > drivers/mmc/host/omap_hsmmc.c | 5 ++++-
> > > 1 file changed, 4 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c
> > > index 7fb0753..7086bd6 100644
> > > --- a/drivers/mmc/host/omap_hsmmc.c
> > > +++ b/drivers/mmc/host/omap_hsmmc.c
> > > @@ -503,8 +503,11 @@ static int omap_hsmmc_reg_get(struct omap_hsmmc_host *host)
> > > host->pbias = devm_regulator_get_optional(host->dev, "pbias");
> > > if (IS_ERR(host->pbias)) {
> > > ret = PTR_ERR(host->pbias);
> > > - if ((ret != -ENODEV) && host->dev->of_node)
> > > + if ((ret != -ENODEV) && host->dev->of_node) {
> > > + dev_err(host->dev,
> > > + "SD card detect fail? enable CONFIG_REGULATOR_PBIAS\n");
> > > return ret;
> > > + }
> > > dev_dbg(host->dev, "unable to get pbias regulator %ld\n",
> > > PTR_ERR(host->pbias));
> > > host->pbias = NULL;
> >
> >
> > Is there a good reason against adding "depends on REGULATOR_PBIAS"
> > to MMC_OMAP_HS?
>
> There are very good reasons not to do this: that will result in
> configurations where MMC_OMAP_HS was set but without REGULATOR_PBIAS
> ending up with MMC_OMAP_HS being disabled. That doesn't help the
> root problem, which is "why has the kernel boot regressed for my
> previous working configuration?"
>
> The solution proposed here adds a message to the boot which points
> out fair and square what needs to be done to rectify the boot
> failure. Adding a dependency just brings up the question "where
> has my MMC driver gone?"
The best thing would be to have no regression. Just printing a
message means I have to build another kernel. But more importantly
the message may not be visible by the user - e.g. if the display has
not yet been initialized.
-- Sebastian
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