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mtd: rawnand: denali: fix a race condition when DMA is kicked

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Based on Linux commit cf51e4b9c34407bf0c3d9b582b7837e047e1df47

Add the register read-back, commenting why this is necessary.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
This commit is contained in:
Masahiro Yamada 2018-12-19 20:03:19 +09:00
parent 8ccfbfb3e1
commit 9d43649a77
1 changed files with 6 additions and 0 deletions
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6
drivers/mtd/nand/raw/denali.c
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@ -587,6 +587,12 @@ static int denali_dma_xfer(struct denali_nand_info *denali, void *buf,
}
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);