[PATCH 4.19 325/346] mtd: rawnand: qcom: Fix DMA sync on FLASH_STATUS register read

[Greg Kroah-Hartman]

From: Praveenkumar I <ipkumar@xxxxxxxxxxxxxx>

commit bc3686021122de953858a5be4cbf6e3f1d821e79 upstream.

After each codeword NAND_FLASH_STATUS is read for possible operational
failures. But there is no DMA sync for CPU operation before reading it
and this leads to incorrect or older copy of DMA buffer in reg_read_buf.

This patch adds the DMA sync on reg_read_buf for CPU before reading it.

Fixes: 5bc36b2bf6e2 ("mtd: rawnand: qcom: check for operation errors in case of raw read")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Praveenkumar I <ipkumar@xxxxxxxxxxxxxx>
Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
Link: https://lore.kernel.org/linux-mtd/1602230872-25616-1-git-send-email-ipkumar@xxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/mtd/nand/raw/qcom_nandc.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/mtd/nand/raw/qcom_nandc.c
+++ b/drivers/mtd/nand/raw/qcom_nandc.c
@@ -1578,6 +1578,8 @@ static int check_flash_errors(struct qco
 	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
 	int i;
 
+	nandc_read_buffer_sync(nandc, true);
+
 	for (i = 0; i < cw_cnt; i++) {
 		u32 flash = le32_to_cpu(nandc->reg_read_buf[i]);