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 <andre.przywara@arm.com>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>
diff --git a/drivers/mmc/sunxi_mmc.c b/drivers/mmc/sunxi_mmc.c
index 178b8cf..aaab0cf 100644
--- a/drivers/mmc/sunxi_mmc.c
+++ b/drivers/mmc/sunxi_mmc.c
@@ -349,10 +349,14 @@
* 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();
}