mtd: rawnand: denali: fix a race condition when DMA is kicked
Based on Linux commit cf51e4b9c34407bf0c3d9b582b7837e047e1df47
Add the register read-back, commenting why this is necessary.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/drivers/mtd/nand/raw/denali.c b/drivers/mtd/nand/raw/denali.c
index bbfa3b6..e0eb133 100644
--- a/drivers/mtd/nand/raw/denali.c
+++ b/drivers/mtd/nand/raw/denali.c
@@ -587,6 +587,12 @@
}
iowrite32(DMA_ENABLE__FLAG, denali->reg + DMA_ENABLE);
+ /*
+ * The ->setup_dma() hook kicks DMA by using the data/command
+ * interface, which belongs to a different AXI port from the
+ * register interface. Read back the register to avoid a race.
+ */
+ ioread32(denali->reg + DMA_ENABLE);
denali_reset_irq(denali);
denali->setup_dma(denali, dma_addr, page, write);