[PATCH v3 18/22] spi: mxic: Fix the transmit path

Miquel Raynal
2021-12-07T09:58:44Z

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>
---
drivers/spi/spi-mxic.c | 28 ++++++++++++----------------
1 file changed, 12 insertions(+), 16 deletions(-)

diff --git a/drivers/spi/spi-mxic.c b/drivers/spi/spi-mxic.c
index 45889947afed..03fce4493aa7 100644
--- 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);