[RFC PATCH 08/10] spi: mxic: Fix the transmit path

[RFC PATCH 08/10] spi: mxic: Fix the transmit path

[Miquel Raynal]

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>
---
 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 96b418293bf2..4fb19e6f94b0 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);
 
-- 
2.27.0

Re: 回信: [RFC PATCH 08/10] spi: mxic: Fix the transmit path

[zhengxunli]

> 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>
> ---
>  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 96b418293bf2..4fb19e6f94b0 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);
> 
> -- 
> 2.27.0
> 

Reviewed-by: Zhengxun Li <zhengxunli@mxic.com.tw>


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