Hi Jerry,
On Mon, Jan 16 2012, r66093@xxxxxxxxxxxxx wrote:
> From: Jerry Huang <Chang-Ming.Huang@xxxxxxxxxxxxx>
>
> SD card read was failing (data crc error)on some cards at
> maximum possible frequency on P1010(CCB frequency set to 400MHz).
> Some clock deviations are also observed at this frequency.
> Hence reduced the mmc clock freq.
>
> Signed-off-by: Priyanka Jain <Priyanka.Jain@xxxxxxxxxxxxx>
> Singed-off-by: Jerry Huang <Chang-Ming.Huang@xxxxxxxxxxxxx>
> CC: Chris Ball <cjb@xxxxxxxxxx>
> Acked-by: Anton Vorontsov <cbouatmailru@xxxxxxxxx>
> ---
> changes for v2:
> - change the property to compatible for quirks
> changes for v3:
> - fix one compile error
> changes for v4:
> - use hooks to suspend/resume the special platform
> changes for v5:
> - add the Acked-by
>
> drivers/mmc/host/sdhci-esdhc.h | 9 ++++++++-
> drivers/mmc/host/sdhci-pltfm.c | 3 +++
> include/linux/mmc/sdhci.h | 2 ++
> 3 files changed, 13 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci-esdhc.h b/drivers/mmc/host/sdhci-esdhc.h
> index b97b2f5..8e00174 100644
> --- a/drivers/mmc/host/sdhci-esdhc.h
> +++ b/drivers/mmc/host/sdhci-esdhc.h
> @@ -1,7 +1,7 @@
> /*
> * Freescale eSDHC controller driver generics for OF and pltfm.
> *
> - * Copyright (c) 2007 Freescale Semiconductor, Inc.
> + * Copyright (c) 2007,2011 Freescale Semiconductor, Inc.
> * Copyright (c) 2009 MontaVista Software, Inc.
> * Copyright (c) 2010 Pengutronix e.K.
> * Author: Wolfram Sang <w.sang@xxxxxxxxxxxxxx>
> @@ -56,6 +56,13 @@ static inline void esdhc_set_clock(struct sdhci_host *host, unsigned int clock)
> if (clock == 0)
> goto out;
>
> + if (host->quirks2 & SDHCI_QUIRK2_RELAX_FREQ) {
> + if (clock > 20000000)
> + clock -= 5000000;
> + if (clock > 40000000)
> + clock -= 5000000;
> + }
> +
> while (host->max_clk / pre_div / 16 > clock && pre_div < 256)
> pre_div *= 2;
>
> diff --git a/drivers/mmc/host/sdhci-pltfm.c b/drivers/mmc/host/sdhci-pltfm.c
> index 04fa130..c932316 100644
> --- a/drivers/mmc/host/sdhci-pltfm.c
> +++ b/drivers/mmc/host/sdhci-pltfm.c
> @@ -81,6 +81,9 @@ void sdhci_get_of_property(struct platform_device *pdev)
> "fsl,mpc8536-esdhc"))
> host->quirks |= SDHCI_QUIRK_BROKEN_TIMEOUT_VAL;
>
> + if (of_device_is_compatible(np, "fsl,p1010-esdhc"))
> + host->quirks2 |= SDHCI_QUIRK2_RELAX_FREQ;
> +
> clk = of_get_property(np, "clock-frequency", &size);
> if (clk && size == sizeof(*clk) && *clk)
> pltfm_host->clock = be32_to_cpup(clk);
> diff --git a/include/linux/mmc/sdhci.h b/include/linux/mmc/sdhci.h
> index e4b6935..f7c1e13 100644
> --- a/include/linux/mmc/sdhci.h
> +++ b/include/linux/mmc/sdhci.h
> @@ -91,6 +91,8 @@ struct sdhci_host {
> unsigned int quirks2; /* More deviations from spec. */
>
> #define SDHCI_QUIRK2_OWN_CARD_DETECTION (1<<0)
> +/* Controller operates the cards at reduced frequency */
> +#define SDHCI_QUIRK2_RELAX_FREQ (1<<1)
>
> int irq; /* Device IRQ */
> void __iomem *ioaddr; /* Mapped address */
I don't think this should be implemented as a global SDHCI quirk,
because I don't think it's ever going to be used on non-ESDHC hardware.
Since you're already handling the clock change in an esdhc-only
function, can you just use your "fsl,p1010-esdhc" test to set some
driver-local flag to use later, instead of involving sdhci.h?
Thanks. (No need to resend the other patches, I'll take this one
separately when it's been reworked.)
- Chris.
--
Chris Ball <cjb@xxxxxxxxxx> <http://printf.net/>
One Laptop Per Child
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