Re: [PATCH v2] mmc: sdhci-of-esdhc: fixup PRESENT_STATE read

[Michael Walle]

Am 2016-11-14 10:37, schrieb Adrian Hunter:
> On 14/11/16 10:50, Michael Walle wrote:
> > Am 2016-11-14 04:00, schrieb Y.B. Lu:
> > > > -----Original Message-----
> > > > From: Michael Walle [mailto:michael@xxxxxxxx]
> > > > Sent: Saturday, November 12, 2016 12:04 AM
> > > > To: linux-kernel@xxxxxxxxxxxxxxx
> > > > Cc: linux-mmc@xxxxxxxxxxxxxxx; Ulf Hansson; Adrian Hunter; yangbo 
> > > > lu;
> > > > Michael Walle
> > > > Subject: [PATCH v2] mmc: sdhci-of-esdhc: fixup PRESENT_STATE read
> > > >
> > > > Since commit 87a18a6a5652 ("mmc: mmc: Use ->card_busy() to detect 
> > > > busy
> > > > cards in __mmc_switch()") the ESDHC driver is broken:
> > > >   mmc0: Card stuck in programming state! __mmc_switch
> > > >   mmc0: error -110 whilst initialising MMC card
> > > >
> > > > Since this commit __mmc_switch() uses ->card_busy(), which is
> > > > sdhci_card_busy() for the esdhc driver. sdhci_card_busy() uses the
> > > > PRESENT_STATE register, specifically the DAT0 signal level bit. But 
> > > > the
> > > > ESDHC uses a non-conformant PRESENT_STATE register, thus a read 
> > > > fixup is
> > > > required to make the driver work again.
> > > >
> > > > Signed-off-by: Michael Walle <michael@xxxxxxxx>
> > > > Fixes: 87a18a6a5652 ("mmc: mmc: Use ->card_busy() to detect busy 
> > > > cards in
> > > > __mmc_switch()")
> > > > ---
> > > > v2:
> > > >  - use lower bits of the original value (that was actually a typo)
> > > >  - add fixes tag
> > > >  - fix typo
> > > >
> > > >  drivers/mmc/host/sdhci-of-esdhc.c | 12 ++++++++++++
> > > >  1 file changed, 12 insertions(+)
> > > >
> > > > diff --git a/drivers/mmc/host/sdhci-of-esdhc.c 
> > > > b/drivers/mmc/host/sdhci-
> > > > of-esdhc.c
> > > > index fb71c86..f9c84bb 100644
> > > > --- a/drivers/mmc/host/sdhci-of-esdhc.c
> > > > +++ b/drivers/mmc/host/sdhci-of-esdhc.c
> > > > @@ -66,6 +66,18 @@ static u32 esdhc_readl_fixup(struct sdhci_host 
> > > > *host,
> > > >              return ret;
> > > >          }
> > > >      }
> > > > +    /*
> > > > +     * The DAT[3:0] line signal levels and the CMD line signal 
> > > > level is
> > > > +     * not compatible with standard SDHC register. Move the
> > > > corresponding
> > > > +     * bits around.
> > > > +     */
> > > > +    if (spec_reg == SDHCI_PRESENT_STATE) {
> > > > +        ret = value & ~0xf8000000;
> > >
> > > [Lu Yangbo-B47093] I think the bits which should be cleaned before
> > > following '|=' are 0x01f00000 not 0xf8000000, right?
> > > :)
> >
> > Its neither 0x01f00000 nor 0xf8000000 :( I'll put the bits definition 
> > into
> > the comment the next time, so everyone can review them. bit[31:24] are 
> > the
> > line DAT[7:0] line signal level. bit[23] is command signal level. All 
> > other
> > bits are the same as in the standard SDHC PRESENT_STATE register.
> >
> > I want to keep all but the upper 9 bits from the original value, 
> > therefore,
> > this should be the correct mask:
> >     ret = value & ~0xff800000;
>
> Why keep bits 22:20 ?  Isn't it more logical to keep 19:0 (i.e. ret = 
> value
> & 0xfffff)

These are 0 according to the datasheet but of course, it makes more 
sense to mask these, too.

-michael