From 0b508ca821d383b2fd68f4b581cf606e329fff36 Mon Sep 17 00:00:00 2001 From: Andre Przywara Date: Fri, 3 Sep 2021 16:49:16 +0100 Subject: [PATCH] sunxi: mmc: A20: Fix MMC optimisation Some SoCs (as seen on A20) seem to misreport the MMC FIFO level if the FIFO is completely full: the level size reads as zero, but the FIFO_FULL bit is set. We won't do a single iteration of the read loop in this case, so will be stuck forever. Check for this situation and use a safe minimal FIFO size instead when we hit this case. This fixes MMC boot on A20 devices after the MMC FIFO optimisation (9faae5457f52). Signed-off-by: Andre Przywara Reviewed-by: Jaehoon Chung --- drivers/mmc/sunxi_mmc.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/mmc/sunxi_mmc.c b/drivers/mmc/sunxi_mmc.c index 178b8cf106..aaab0cf866 100644 --- a/drivers/mmc/sunxi_mmc.c +++ b/drivers/mmc/sunxi_mmc.c @@ -349,10 +349,14 @@ static int mmc_trans_data_by_cpu(struct sunxi_mmc_priv *priv, struct mmc *mmc, * register without checking the status register after every * read. That saves half of the costly MMIO reads, effectively * doubling the read performance. + * Some SoCs (A20) report a level of 0 if the FIFO is + * completely full (value masked out?). Use a safe minimal + * FIFO size in this case. */ - for (in_fifo = SUNXI_MMC_STATUS_FIFO_LEVEL(status); - in_fifo > 0; - in_fifo--) + in_fifo = SUNXI_MMC_STATUS_FIFO_LEVEL(status); + if (in_fifo == 0 && (status & SUNXI_MMC_STATUS_FIFO_FULL)) + in_fifo = 32; + for (; in_fifo > 0; in_fifo--) buff[i++] = readl_relaxed(&priv->reg->fifo); dmb(); } -- 2.39.5