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SubjectRe: [PATCH] mmc: Added quirks for Ricoh 1180:e823 lower base clock frequency
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Hi Manoj, adding linux-mmc@,

On Mon, Jul 11 2011, Manoj Iyer wrote:
> Ricoh 1180:e823 does not recognize certain types of SD/MMC cards.
> Lowering the SD base clock frequency from 200Mhz to 50Mhz fixes
> this issue. This solution was suggest by Koji Matsumuro, Ricoh
> Company,Ltd.
>
> BugLink: http://launchpad.net/bugs/773524
> Signed-off-by: Manoj Iyer <manoj.iyer@canonical.com>
> Tested-by: Daniel Manrique <daniel.manrique@canonical.com>
> Cc: Koji Matsumuro <matsumur@nts.ricoh.co.jp>
> ---
> drivers/pci/quirks.c | 24 ++++++++++++++++++++++++
> 1 files changed, 24 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index 02145e9..fe5bffa 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -2758,6 +2758,30 @@ static void ricoh_mmc_fixup_r5c832(struct pci_dev *dev)
>
> dev_notice(&dev->dev, "proprietary Ricoh MMC controller disabled (via firewire function)\n");
> dev_notice(&dev->dev, "MMC cards are now supported by standard SDHCI controller\n");
> +
> + /*
> + * RICOH 0xe823 SD/MMC card reader fails to recognize
> + * certain types of SD/MMC cards. Lowering the SD base
> + * clock frequency from 200Mhz to 50Mhz fixes this issue.
> + *
> + * 0x150 - SD2.0 mode enable for changing base clock
> + * frequency to 50Mhz
> + * 0xe1 - Base clock frequency
> + * 0x32 - 50Mhz new clock frequency
> + * 0xf9 - Key register for 0x150
> + * 0xfc - key register for 0xe1
> + */
> + if (dev->device == PCI_DEVICE_ID_RICOH_R5CE823) {
> + pci_write_config_byte(dev, 0xf9, 0xfc);
> + pci_write_config_byte(dev, 0x150, 0x10);
> + pci_write_config_byte(dev, 0xf9, 0x00);
> + pci_write_config_byte(dev, 0xfc, 0x01);
> + pci_write_config_byte(dev, 0xe1, 0x32);
> + pci_write_config_byte(dev, 0xfc, 0x00);
> +
> + dev_notice(&dev->dev, "Controller base frequency changed to 50Mhz)\n");

There's an erroneous ")" in this string; I'll replace it with a "." if
this patch goes in via my tree. Also, let's make it "MMC controller"
instead of just "Controller".

> + }
> +
> }
> DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_RICOH, PCI_DEVICE_ID_RICOH_R5C832, ricoh_mmc_fixup_r5c832);
> DECLARE_PCI_FIXUP_RESUME_EARLY(PCI_VENDOR_ID_RICOH, PCI_DEVICE_ID_RICOH_R5C832, ricoh_mmc_fixup_r5c832);

Have you checked to see how SD I/O performance differs after this change?

(If this is significant, perhaps we want to try lowering the frequency
only after a card starts returning errors, since some cards work fine
at the higher frequency.)

Thanks,

- Chris.
--
Chris Ball <cjb@laptop.org> <http://printf.net/>
One Laptop Per Child


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