code is fine.
On Nov 19, 2010, at 1:53 PM, Chris Ball wrote:
> On Fri, Nov 19, 2010 at 09:40:02PM +0000, Chris Ball wrote:
>> I don't see why we should re-read ctrl here, since we've already written
>> it back to the device at this point, and we don't use it anywhere below
>> this line.
>
> Ah, I see why now; please ignore this.
>
> Here's a rebased version of the patch, with some more comments:
>
> From: Philip Rakity <prakity@xxxxxxxxxxx>
> Date: Fri, 19 Nov 2010 16:48:39 -0500
> Subject: [PATCH] mmc: sdhci: 8-bit bus width changes
>
> We now:
> * check for a v3 controller before setting 8-bit bus width
> * offer a callback for platform code to switch to 8-bit mode, which
> allows non-v3 controllers to support it
> * introduce a quirk to specify that the board designers have indeed
> brought out all the pins for 8-bit to the slot.
>
> We were previously relying only on whether the controller supported
> 8-bit, which doesn't tell us anything about the pin configuration in
> the board design.
>
> Signed-off-by: Philip Rakity <prakity@xxxxxxxxxxx>
> Tested-by: Giuseppe Cavallaro <peppe.cavallaro@xxxxxx>
> Signed-off-by: Chris Ball <cjb@xxxxxxxxxx>
> ---
> drivers/mmc/host/sdhci.c | 48 +++++++++++++++++++++++++++++++++-----------
> drivers/mmc/host/sdhci.h | 5 +++-
> include/linux/mmc/sdhci.h | 2 +
> 3 files changed, 42 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index 154cbf8..f1f9658 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -1185,17 +1185,31 @@ static void sdhci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
> if (host->ops->platform_send_init_74_clocks)
> host->ops->platform_send_init_74_clocks(host, ios->power_mode);
>
> - ctrl = sdhci_readb(host, SDHCI_HOST_CONTROL);
> -
> - if (ios->bus_width == MMC_BUS_WIDTH_8)
> - ctrl |= SDHCI_CTRL_8BITBUS;
> - else
> - ctrl &= ~SDHCI_CTRL_8BITBUS;
> + /*
> + * If your platform has 8-bit width support but is not a v3 controller,
> + * or if it requires special setup code, you should implement that in
> + * platform_8bit_width().
> + */
> + if (host->ops->platform_8bit_width)
> + host->ops->platform_8bit_width(host, ios->bus_width);
> + else {
> + ctrl = sdhci_readb(host, SDHCI_HOST_CONTROL);
> + if (ios->bus_width == MMC_BUS_WIDTH_8) {
> + ctrl &= ~SDHCI_CTRL_4BITBUS;
> + if (host->version >= SDHCI_SPEC_300)
> + ctrl |= SDHCI_CTRL_8BITBUS;
> + } else {
> + if (host->version >= SDHCI_SPEC_300)
> + ctrl &= ~SDHCI_CTRL_8BITBUS;
> + if (ios->bus_width == MMC_BUS_WIDTH_4)
> + ctrl |= SDHCI_CTRL_4BITBUS;
> + else
> + ctrl &= ~SDHCI_CTRL_4BITBUS;
> + }
> + sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL);
> + }
>
> - if (ios->bus_width == MMC_BUS_WIDTH_4)
> - ctrl |= SDHCI_CTRL_4BITBUS;
> - else
> - ctrl &= ~SDHCI_CTRL_4BITBUS;
> + ctrl = sdhci_readb(host, SDHCI_HOST_CONTROL);
>
> if ((ios->timing == MMC_TIMING_SD_HS ||
> ios->timing == MMC_TIMING_MMC_HS)
> @@ -1855,11 +1869,21 @@ int sdhci_add_host(struct sdhci_host *host)
> mmc->f_min = host->max_clk / SDHCI_MAX_DIV_SPEC_300;
> else
> mmc->f_min = host->max_clk / SDHCI_MAX_DIV_SPEC_200;
> +
> mmc->f_max = host->max_clk;
> mmc->caps |= MMC_CAP_SDIO_IRQ;
>
> - if (!(host->quirks & SDHCI_QUIRK_FORCE_1_BIT_DATA))
> - mmc->caps |= MMC_CAP_4_BIT_DATA | MMC_CAP_8_BIT_DATA;
> + /*
> + * A controller may support 8-bit width, but the board itself
> + * might not have the pins brought out. So, boards that support
> + * 8-bit width should set the below quirk, and we won't assume
> + * that devices without the quirk can use 8-bit width.
> + */
> + if (!(host->quirks & SDHCI_QUIRK_FORCE_1_BIT_DATA)) {
> + mmc->caps |= MMC_CAP_4_BIT_DATA;
> + if (host->quirks & SDHCI_QUIRK_SLOT_CAN_DO_8_BITS)
> + mmc->caps |= MMC_CAP_8_BIT_DATA;
> + }
>
> if (caps & SDHCI_CAN_DO_HISPD)
> mmc->caps |= MMC_CAP_SD_HIGHSPEED | MMC_CAP_MMC_HIGHSPEED;
> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
> index d52a716..e42d7f0 100644
> --- a/drivers/mmc/host/sdhci.h
> +++ b/drivers/mmc/host/sdhci.h
> @@ -76,7 +76,7 @@
> #define SDHCI_CTRL_ADMA1 0x08
> #define SDHCI_CTRL_ADMA32 0x10
> #define SDHCI_CTRL_ADMA64 0x18
> -#define SDHCI_CTRL_8BITBUS 0x20
> +#define SDHCI_CTRL_8BITBUS 0x20
>
> #define SDHCI_POWER_CONTROL 0x29
> #define SDHCI_POWER_ON 0x01
> @@ -155,6 +155,7 @@
> #define SDHCI_CLOCK_BASE_SHIFT 8
> #define SDHCI_MAX_BLOCK_MASK 0x00030000
> #define SDHCI_MAX_BLOCK_SHIFT 16
> +#define SDHCI_CAN_DO_8BIT 0x00040000
> #define SDHCI_CAN_DO_ADMA2 0x00080000
> #define SDHCI_CAN_DO_ADMA1 0x00100000
> #define SDHCI_CAN_DO_HISPD 0x00200000
> @@ -215,6 +216,8 @@ struct sdhci_ops {
> unsigned int (*get_max_clock)(struct sdhci_host *host);
> unsigned int (*get_min_clock)(struct sdhci_host *host);
> unsigned int (*get_timeout_clock)(struct sdhci_host *host);
> + int (*platform_8bit_width)(struct sdhci_host *host,
> + int width);
> void (*platform_send_init_74_clocks)(struct sdhci_host *host,
> u8 power_mode);
> unsigned int (*get_ro)(struct sdhci_host *host);
> diff --git a/include/linux/mmc/sdhci.h b/include/linux/mmc/sdhci.h
> index 1fdc673..7fdcfca 100644
> --- a/include/linux/mmc/sdhci.h
> +++ b/include/linux/mmc/sdhci.h
> @@ -83,6 +83,8 @@ struct sdhci_host {
> #define SDHCI_QUIRK_MULTIBLOCK_READ_ACMD12 (1<<28)
> /* Controller doesn't have HISPD bit field in HI-SPEED SD card */
> #define SDHCI_QUIRK_NO_HISPD_BIT (1<<29)
> +/* Slot has 8 data pins going to eMMC/MMC card */
> +#define SDHCI_QUIRK_SLOT_CAN_DO_8_BITS (1<<30)
>
> int irq; /* Device IRQ */
> void __iomem *ioaddr; /* Mapped address */
> --
> Chris Ball <cjb@xxxxxxxxxx> <http://printf.net/>
> One Laptop Per Child
--
To unsubscribe from this list: send the line "unsubscribe linux-mmc" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
