From: Jon Medhurst jon.medhurst@linaro.org
The new IO FPGA implementation for Versatile Express contains an MMCI (PL180) cell with the FIFO extended to 128 words. This causes the read_bytes() function to go into an infinite loop; as it will wait for for the half-full signal (SDI_STA_RXFIFOBR) if there are more than 8 words remaining (SDI_FIFO_BURST_SIZE), but it won't receive this signal once there are fewer than 64 words left to transfer.
One possible fix is to add some build time configuration to change SDI_FIFO_BURST_SIZE for the new implementation. However, the problematic code only seems to exist as a small performance optimisation, so the solution implemented by this patch is to simply remove it. The error checking following the loop is also removed as this will be handled by code further down the function.
Cc: Andy Fleming afleming@gmail.com Signed-off-by: Jon Medhurst jon.medhurst@linaro.org ---
If it is desirable to keep the burst read optimisation, then an alternative solution would be to keep the loop and add an if clause to do a single read if the fifo doesn't have enough for a burst.
--- drivers/mmc/arm_pl180_mmci.c | 26 -------------------------- 1 files changed, 0 insertions(+), 26 deletions(-)
diff --git a/drivers/mmc/arm_pl180_mmci.c b/drivers/mmc/arm_pl180_mmci.c index ed296ee..e6467a2 100644 --- a/drivers/mmc/arm_pl180_mmci.c +++ b/drivers/mmc/arm_pl180_mmci.c @@ -111,7 +111,6 @@ static int do_command(struct mmc *dev, struct mmc_cmd *cmd) static int read_bytes(struct mmc *dev, u32 *dest, u32 blkcount, u32 blksize) { u32 *tempbuff = dest; - int i; u64 xfercount = blkcount * blksize; struct mmc_host *host = dev->priv; u32 status, status_err; @@ -121,31 +120,6 @@ static int read_bytes(struct mmc *dev, u32 *dest, u32 blkcount, u32 blksize) status = readl(&host->base->status); status_err = status & (SDI_STA_DCRCFAIL | SDI_STA_DTIMEOUT | SDI_STA_RXOVERR); - while (!status_err && - (xfercount >= SDI_FIFO_BURST_SIZE * sizeof(u32))) { - if (status & SDI_STA_RXFIFOBR) { - for (i = 0; i < SDI_FIFO_BURST_SIZE; i++) - *(tempbuff + i) = readl(&host->base->fifo); - tempbuff += SDI_FIFO_BURST_SIZE; - xfercount -= SDI_FIFO_BURST_SIZE * sizeof(u32); - } - status = readl(&host->base->status); - status_err = status & - (SDI_STA_DCRCFAIL | SDI_STA_DTIMEOUT | SDI_STA_RXOVERR); - } - - if (status & SDI_STA_DTIMEOUT) { - printf("Read data timed out, xfercount: %llu, status: 0x%08X\n", - xfercount, status); - return -ETIMEDOUT; - } else if (status & SDI_STA_DCRCFAIL) { - printf("Read data blk CRC error: 0x%x\n", status); - return -EILSEQ; - } else if (status & SDI_STA_RXOVERR) { - printf("Read data RX overflow error\n"); - return -EIO; - } - while ((!status_err) && (xfercount >= sizeof(u32))) { if (status & SDI_STA_RXDAVL) { *(tempbuff) = readl(&host->base->fifo);