spi: mxic: Fix the transmit path

By working with external hardware ECC engines, we figured out that
Under certain circumstances, it is needed for the SPI controller to
check INT_TX_EMPTY and INT_RX_NOT_EMPTY in both receive and transmit
path (not only in the receive path). The delay penalty being
negligible, move this code in the common path.

Fixes: b942d80b0a39 ("spi: Add MXIC controller driver")
Cc: stable@vger.kernel.org
Suggested-by: Mason Yang <masonccyang@mxic.com.tw>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Zhengxun Li <zhengxunli@mxic.com.tw>
Reviewed-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/linux-mtd/20220127091808.1043392-10-miquel.raynal@bootlin.com

diff --git a/drivers/spi/spi-mxic.c b/drivers/spi/spi-mxic.c
index 6bec0a7c77d3840d11b7ba7304122a52ed24debd..22a82f5f74b54e024c323ab0ab2d3e24247f34e6 100644 (file)
--- a/drivers/spi/spi-mxic.c
+++ b/drivers/spi/spi-mxic.c
@@ -304,25 +304,21 @@ static int mxic_spi_data_xfer(struct mxic_spi *mxic, const void *txbuf,
 
                writel(data, mxic->regs + TXD(nbytes % 4));
 
+               ret = readl_poll_timeout(mxic->regs + INT_STS, sts,
+                                        sts & INT_TX_EMPTY, 0, USEC_PER_SEC);
+               if (ret)
+                       return ret;
+
+               ret = readl_poll_timeout(mxic->regs + INT_STS, sts,
+                                        sts & INT_RX_NOT_EMPTY, 0,
+                                        USEC_PER_SEC);
+               if (ret)
+                       return ret;
+
+               data = readl(mxic->regs + RXD);
                if (rxbuf) {
-                       ret = readl_poll_timeout(mxic->regs + INT_STS, sts,
-                                                sts & INT_TX_EMPTY, 0,
-                                                USEC_PER_SEC);
-                       if (ret)
-                               return ret;
-
-                       ret = readl_poll_timeout(mxic->regs + INT_STS, sts,
-                                                sts & INT_RX_NOT_EMPTY, 0,
-                                                USEC_PER_SEC);
-                       if (ret)
-                               return ret;
-
-                       data = readl(mxic->regs + RXD);
                        data >>= (8 * (4 - nbytes));
                        memcpy(rxbuf + pos, &data, nbytes);
-                       WARN_ON(readl(mxic->regs + INT_STS) & INT_RX_NOT_EMPTY);
-               } else {
-                       readl(mxic->regs + RXD);
                }
                WARN_ON(readl(mxic->regs + INT_STS) & INT_RX_NOT_EMPTY);