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

S, Venkatraman
2011-07-19T15:58:44Z

On Mon, Jul 18, 2011 at 11:31 AM, Zang Roy-R61911 <r61911@freescale.com> wrote:
>
>
>> -----Original Message-----
>> From: S, Venkatraman [mailto:svenkatr@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@freescale.com> wrote:
>> > From: Xu lei <B33228@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@freescale.com>
>> > Signed-off-by: Roy Zang <tie-fei.zang@freescale.com>
>> > Signed-off-by: Kumar Gala <galak@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

There aren't very hard rules on this. Simple #defines are good, as a
one off usage.
These bit mask fields are very verbose, and they tend to grow more
than a screenful.
The remaining bits will never be defined ?