[PATCH 2/3] eSDHC: Fix errors when booting kernel with fsl esdhc

[Zang Roy-R61911]

> -----Original Message-----
> From: S, Venkatraman [mailto:svenkatr at ti.com]
> Sent: Tuesday, July 05, 2011 14:17 PM
> To: Zang Roy-R61911
> Cc: linux-mmc; linuxppc-dev; cbouatmailru; akpm; Xu Lei-B33228; Kumar Gala
> Subject: Re: [PATCH 2/3] eSDHC: Fix errors when booting kernel with fsl esdhc
> 
> On Tue, Jul 5, 2011 at 9:49 AM, Roy Zang <tie-fei.zang at freescale.com> wrote:
> > From: Xu lei <B33228 at freescale.com>
> >
> > When esdhc module was enabled in p5020, there were following errors:
> >
> > mmc0: Timeout waiting for hardware interrupt.
> > mmc0: error -110 whilst initialising SD card
> > mmc0: Unexpected interrupt 0x02000000.
> > mmc0: Timeout waiting for hardware interrupt.
> > mmc0: error -110 whilst initialising SD card
> > mmc0: Unexpected interrupt 0x02000000.
> >
> > It is because ESDHC controller has different bit setting for PROCTL
> > register, when kernel sets Power Control Register by method for standard
> > SD Host Specification, it would overwritten FSL ESDHC PROCTL[DMAS];
> > when it set Host Control Registers[DMAS], it sets PROCTL[EMODE] and
> > PROCTL[D3CD]. These operations will set bad bits for PROCTL Register
> > on FSL ESDHC Controller and cause errors, so this patch will make esdhc
> > driver access FSL PROCTL Register according to block guide instead of
> > standard SD Host Specification.
> >
> > For some FSL chips, such as MPC8536/P2020, PROCTL[VOLT_SEL] and PROCTL[DMAS]
> > bits are reserved and even if they are set to wrong bits there is no error.
> > But considering that all FSL ESDHC Controller register map is not fully
> > compliant to standard SD Host Specification, we put the patch to all of
> > FSL ESDHC Controllers.
> >
> > Signed-off-by: Lei Xu <B33228 at freescale.com>
> > Signed-off-by: Roy Zang <tie-fei.zang at freescale.com>
> > Signed-off-by: Kumar Gala <galak at kernel.crashing.org>
> > ---
> >  drivers/mmc/host/sdhci-of-core.c |    3 ++
> >  drivers/mmc/host/sdhci.c         |   62 ++++++++++++++++++++++++++++++-----
> --
> >  include/linux/mmc/sdhci.h        |    6 ++-
> >  3 files changed, 57 insertions(+), 14 deletions(-)
[snip]

> > diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> > index 58d5436..77174e5 100644
> > --- a/drivers/mmc/host/sdhci.c
> > +++ b/drivers/mmc/host/sdhci.c
> > @@ -674,7 +674,7 @@ static void sdhci_set_transfer_irqs(struct sdhci_host
> *host)
> >  static void sdhci_prepare_data(struct sdhci_host *host, struct mmc_command
> *cmd)
> >  {
> >        u8 count;
> > -       u8 ctrl;
> > +       u32 ctrl;
> >        struct mmc_data *data = cmd->data;
> >        int ret;
> >
> > @@ -807,14 +807,28 @@ static void sdhci_prepare_data(struct sdhci_host *host,
> struct mmc_command *cmd)
> >         * is ADMA.
> >         */
> >        if (host->version >= SDHCI_SPEC_200) {
> > -               ctrl = sdhci_readb(host, SDHCI_HOST_CONTROL);
> > -               ctrl &= ~SDHCI_CTRL_DMA_MASK;
> > -               if ((host->flags & SDHCI_REQ_USE_DMA) &&
> > -                       (host->flags & SDHCI_USE_ADMA))
> > -                       ctrl |= SDHCI_CTRL_ADMA32;
> > -               else
> > -                       ctrl |= SDHCI_CTRL_SDMA;
> > -               sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL);
> > +               if (host->quirks & SDHCI_QUIRK_QORIQ_PROCTL_WEIRD) {
> > +#define ESDHCI_PROCTL_DMAS_MASK                0x00000300
> > +#define ESDHCI_PROCTL_ADMA32           0x00000200
> > +#define ESDHCI_PROCTL_SDMA             0x00000000
> 
> Breaks the code flow / readability. Can be moved to top of the file ?
The defines are only used in the following section. Why it will break
the readability?
I can also see this kind of define in the file
...
#define SAMPLE_COUNT    5

static int sdhci_get_ro(struct mmc_host *mmc)
...

Any rule should follow?


[snip]
> > @@ -1162,6 +1189,17 @@ static void sdhci_set_power(struct sdhci_host *host,
> unsigned short power)
> >
> >        host->pwr = pwr;
> >
> > +       /* Now FSL ESDHC Controller has no Bus Power bit,
> > +        * and PROCTL[21] bit is for voltage selection */
> 
> Multiline comment style needed..
Will update.
please help to explain your previous comment.
Thanks.
Roy