[RFC PATCH v1] mtd: rawnand: meson: invalidate cache on polling ECC bit

[Arseniy Krasnov]

'info_buf' memory is cached and driver polls ECC bit in it. This bit
is set by the NAND controller. If 'usleep_range()' returns before device
sets this bit, 'info_buf' will be cached and driver won't see update of
this bit and will loop forever.

Fixes: 8fae856c5350 ("mtd: rawnand: meson: add support for Amlogic NAND flash controller")
Signed-off-by: Arseniy Krasnov <AVKrasnov at sberdevices.ru>
---
 drivers/mtd/nand/raw/meson_nand.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/nand/raw/meson_nand.c b/drivers/mtd/nand/raw/meson_nand.c
index 5ee01231ac4c..2c05c08a0eaf 100644
--- a/drivers/mtd/nand/raw/meson_nand.c
+++ b/drivers/mtd/nand/raw/meson_nand.c
@@ -176,6 +176,7 @@ struct meson_nfc {
 
 	dma_addr_t daddr;
 	dma_addr_t iaddr;
+	u32 info_bytes;
 
 	unsigned long assigned_cs;
 };
@@ -503,6 +504,7 @@ static int meson_nfc_dma_buffer_setup(struct nand_chip *nand, void *databuf,
 					 nfc->daddr, datalen, dir);
 			return ret;
 		}
+		nfc->info_bytes = infolen;
 		cmd = GENCMDIADDRL(NFC_CMD_AIL, nfc->iaddr);
 		writel(cmd, nfc->reg_base + NFC_REG_CMD);
 
@@ -520,8 +522,10 @@ static void meson_nfc_dma_buffer_release(struct nand_chip *nand,
 	struct meson_nfc *nfc = nand_get_controller_data(nand);
 
 	dma_unmap_single(nfc->dev, nfc->daddr, datalen, dir);
-	if (infolen)
+	if (infolen) {
 		dma_unmap_single(nfc->dev, nfc->iaddr, infolen, dir);
+		nfc->info_bytes = 0;
+	}
 }
 
 static int meson_nfc_read_buf(struct nand_chip *nand, u8 *buf, int len)
@@ -710,6 +714,8 @@ static void meson_nfc_check_ecc_pages_valid(struct meson_nfc *nfc,
 		usleep_range(10, 15);
 		/* info is updated by nfc dma engine*/
 		smp_rmb();
+		dma_sync_single_for_cpu(nfc->dev, nfc->iaddr, nfc->info_bytes,
+					DMA_FROM_DEVICE);
 		ret = *info & ECC_COMPLETE;
 	} while (!ret);
 }
-- 
2.35.0