While trying to enable the dw_mmc on rk3188 I managed to confuse and hang the dw_mmc controller into not delivering further data. The fifo state never became ready and the driver was iterating in the while loop reading 0-byte packets forever.
So inspired by how other implementations handle this, check the fifo- state beforhand and add a timeout to catch any glaring fifo issues without hanging uboot altogether.
Signed-off-by: Heiko Stuebner heiko@sntech.de --- drivers/mmc/dw_mmc.c | 32 ++++++++++++++++++++++++++++++-- include/dwmmc.h | 2 ++ 2 files changed, 32 insertions(+), 2 deletions(-)
diff --git a/drivers/mmc/dw_mmc.c b/drivers/mmc/dw_mmc.c index 13180fc0d6..3c702b3ed8 100644 --- a/drivers/mmc/dw_mmc.c +++ b/drivers/mmc/dw_mmc.c @@ -92,6 +92,24 @@ static void dwmci_prepare_data(struct dwmci_host *host, dwmci_writel(host, DWMCI_BYTCNT, data->blocksize * data->blocks); }
+static int dwmci_fifo_ready(struct dwmci_host *host, u32 bit, u32 *len) +{ + u32 timeout = 20000; + + *len = dwmci_readl(host, DWMCI_STATUS); + while (--timeout && (*len & bit)) { + udelay(200); + *len = dwmci_readl(host, DWMCI_STATUS); + } + + if (!timeout) { + debug("%s: FIFO underflow timeout\n", __func__); + return -ETIMEDOUT; + } + + return 0; +} + static int dwmci_data_transfer(struct dwmci_host *host, struct mmc_data *data) { int ret = 0; @@ -122,7 +140,12 @@ static int dwmci_data_transfer(struct dwmci_host *host, struct mmc_data *data) if (data->flags == MMC_DATA_READ && (mask & DWMCI_INTMSK_RXDR)) { while (size) { - len = dwmci_readl(host, DWMCI_STATUS); + ret = dwmci_fifo_ready(host, + DWMCI_FIFO_EMPTY, + &len); + if (ret < 0) + break; + len = (len >> DWMCI_FIFO_SHIFT) & DWMCI_FIFO_MASK; len = min(size, len); @@ -136,7 +159,12 @@ static int dwmci_data_transfer(struct dwmci_host *host, struct mmc_data *data) } else if (data->flags == MMC_DATA_WRITE && (mask & DWMCI_INTMSK_TXDR)) { while (size) { - len = dwmci_readl(host, DWMCI_STATUS); + ret = dwmci_fifo_ready(host, + DWMCI_FIFO_FULL, + &len); + if (ret < 0) + break; + len = fifo_depth - ((len >> DWMCI_FIFO_SHIFT) & DWMCI_FIFO_MASK); diff --git a/include/dwmmc.h b/include/dwmmc.h index bc1d6e3abb..0f9d51b557 100644 --- a/include/dwmmc.h +++ b/include/dwmmc.h @@ -103,6 +103,8 @@ #define DWMCI_CTYPE_8BIT (1 << 16)
/* Status Register */ +#define DWMCI_FIFO_EMPTY (1 << 2) +#define DWMCI_FIFO_FULL (1 << 3) #define DWMCI_BUSY (1 << 9) #define DWMCI_FIFO_MASK 0x1fff #define DWMCI_FIFO_SHIFT 17