Hi,
On Wed, Feb 08 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>
Thanks, just one comment below:
> ---
> 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
> changes for v6:
> - move the workaround codes to special platform from header file
> changes for v7:
> - don't use quirks to check the platform support
>
> drivers/mmc/host/sdhci-of-esdhc.c | 19 ++++++++++++++++++-
> 1 files changed, 18 insertions(+), 1 deletions(-)
> drivers/mmc/host/sdhci-of-esdhc.c | 24 ++++++++++++++++++++++--
> 1 files changed, 22 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci-of-esdhc.c b/drivers/mmc/host/sdhci-of-esdhc.c
> index 2ef52f4..acac541 100644
> --- a/drivers/mmc/host/sdhci-of-esdhc.c
> +++ b/drivers/mmc/host/sdhci-of-esdhc.c
> @@ -1,7 +1,7 @@
> /*
> * Freescale eSDHC controller driver.
> *
> - * Copyright (c) 2007, 2010 Freescale Semiconductor, Inc.
> + * Copyright (c) 2007, 2010, 2012 Freescale Semiconductor, Inc.
> * Copyright (c) 2009 MontaVista Software, Inc.
> *
> * Authors: Xiaobo Xie <X.Xie@xxxxxxxxxxxxx>
> @@ -14,6 +14,7 @@
> */
>
> #include <linux/io.h>
> +#include <linux/of.h>
> #include <linux/delay.h>
> #include <linux/module.h>
> #include <linux/mmc/host.h>
> @@ -114,6 +115,25 @@ static unsigned int esdhc_of_get_min_clock(struct sdhci_host *host)
> return pltfm_host->clock / 256 / 16;
> }
>
> +static void esdhc_of_set_clock(struct sdhci_host *host, unsigned int clock)
> +{
> + /* Workaround to reduce the clock frequency for p1010 esdhc */
> + if (of_find_compatible_node(NULL, NULL, "fsl,p1010-esdhc")) {
> + if (clock == 0) {
> + host->clock = clock;
> + return;
> + }
Is this if (clock == 0) necessary? You'll be calling esdhc_set_clock()
immediately afterwards, and it performs the same test.
> +
> + if (clock > 20000000)
> + clock -= 5000000;
> + if (clock > 40000000)
> + clock -= 5000000;
> + }
> +
> + /* Set the clock */
> + esdhc_set_clock(host, clock);
> +}
> +
> #ifdef CONFIG_PM
> static u32 esdhc_proctl;
> static void esdhc_of_suspend(struct sdhci_host *host)
> @@ -135,7 +155,7 @@ static struct sdhci_ops sdhci_esdhc_ops = {
> .write_l = sdhci_be32bs_writel,
> .write_w = esdhc_writew,
> .write_b = esdhc_writeb,
> - .set_clock = esdhc_set_clock,
> + .set_clock = esdhc_of_set_clock,
> .enable_dma = esdhc_of_enable_dma,
> .get_max_clock = esdhc_of_get_max_clock,
> .get_min_clock = esdhc_of_get_min_clock,
Thanks,
- Chris.
--
Chris Ball <cjb@xxxxxxxxxx> <http://printf.net/>
One Laptop Per Child
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