Currently we find that if a usdhc is choosed to boot system, then ROM code will set the burst length enable bit of this usdhc as 0. This will make performance drop a lot if this usdhc's burst length is configed. So this patch set back the burst_length_enable bit as 1, which is the default value, and means burst length is enabled for INCR. Signed-off-by: Haibo Chen <haibo.chen@xxxxxxxxxxxxx> --- drivers/mmc/host/sdhci-esdhc-imx.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c index 298551d..ac8ec01 100644 --- a/drivers/mmc/host/sdhci-esdhc-imx.c +++ b/drivers/mmc/host/sdhci-esdhc-imx.c @@ -32,6 +32,7 @@ #include "sdhci-esdhc.h" #define ESDHC_CTRL_D3CD 0x08 +#define ESDHC_BURST_LEN_EN_INCR (1 << 27) /* VENDOR SPEC register */ #define ESDHC_VENDOR_SPEC 0xc0 #define ESDHC_VENDOR_SPEC_SDIO_QUIRK (1 << 1) @@ -1163,6 +1164,21 @@ static int sdhci_esdhc_imx_probe(struct platform_device *pdev) host->quirks2 |= SDHCI_QUIRK2_PRESET_VALUE_BROKEN; host->mmc->caps |= MMC_CAP_1_8V_DDR; + /* + * ROM code will change the bit burst_length_enable setting + * to zero if this usdhc is choosed to boot system. Change + * it back here, otherwise it will impact the performance a + * lot. This bit is used to enable/disable the burst length + * for the external AHB2AXI bridge, it's usefully especially + * for INCR transfer because without burst length indicator, + * the AHB2AXI bridge does not know the burst length in + * advance. And without burst length indicator, AHB INCR + * transfer can only be converted to singles on the AXI side. + */ + writel(readl(host->ioaddr + SDHCI_HOST_CONTROL) + | ESDHC_BURST_LEN_EN_INCR, + host->ioaddr + SDHCI_HOST_CONTROL); + if (!(imx_data->socdata->flags & ESDHC_FLAG_HS200)) host->quirks2 |= SDHCI_QUIRK2_BROKEN_HS200; -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
