Re: [RFC v2 2/2] mmc: sdhci: Ignore capability register when it comes to speeds and use DT binding instead when sdhci-cap-speed-modes-broken is set.

[Zach Brown]

On Mon, Oct 24, 2016 at 10:34:46AM +0300, Adrian Hunter wrote:
> On 22/10/16 00:35, Zach Brown wrote:
> > When the sdhci-cap-speed-modes-broken DT property is set, the driver
> > will ignore the bits of the capability registers that correspond to
> > speed modes.
> >
> > Signed-off-by: Zach Brown <zach.brown@xxxxxx>
> > ---
> >  drivers/mmc/host/sdhci.c | 10 ++++++++++
> >  1 file changed, 10 insertions(+)
> >
> > diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> > index 1e25b01..59c62d3 100644
> > --- a/drivers/mmc/host/sdhci.c
> > +++ b/drivers/mmc/host/sdhci.c
> > @@ -22,6 +22,7 @@
> >  #include <linux/scatterlist.h>
> >  #include <linux/regulator/consumer.h>
> >  #include <linux/pm_runtime.h>
> > +#include <linux/of.h>
> >
> >  #include <linux/leds.h>
> >
> > @@ -3013,10 +3014,19 @@ void __sdhci_read_caps(struct sdhci_host *host, u16 *ver, u32 *caps, u32 *caps1)
> >
> >  	host->caps = caps ? *caps : sdhci_readl(host, SDHCI_CAPABILITIES);
> >
> > +	if (of_property_read_bool(mmc_dev(host->mmc)->of_node,
> > +				  "sdhci-cap-speed-modes-broken"))
>
> It rather begs the question: if you are going to do something sdhci
> specific, why not just read the whole of the caps register from DT?
>

Throwing out the whole of the caps register seems like overkill. Also
there are some things set by the caps that are not available in the DT.
For example, SDHCI_CAN_64BIT is set by the cap register and is used in
sdhci_setup_host to set host->flags SDHCI_USE_64_BIT_DMA.