Patch "spi: lpspi: Let watermark change with send data length" has been added to the 4.19-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    spi: lpspi: Let watermark change with send data length

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     spi-lpspi-let-watermark-change-with-send-data-length.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 4d829d95ea8b938bb97c0cfc0c5c42569577162e
Author: Clark Wang <xiaoning.wang@xxxxxxx>
Date:   Fri Dec 7 02:50:38 2018 +0000

    spi: lpspi: Let watermark change with send data length
    
    [ Upstream commit cf86874bb9bdb99ba3620428b59b0408fbc703d0 ]
    
    Configure watermark to change with the length of the sent data.
    Support LPSPI sending message shorter than tx/rxfifosize.
    
    Signed-off-by: Clark Wang <xiaoning.wang@xxxxxxx>
    Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
    Stable-dep-of: 730bbfaf7d48 ("spi: spi-fsl-lpspi: Fix scldiv calculation")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/spi/spi-fsl-lpspi.c b/drivers/spi/spi-fsl-lpspi.c
index cbf165e7bd17b..08dcc3c22e883 100644
--- a/drivers/spi/spi-fsl-lpspi.c
+++ b/drivers/spi/spi-fsl-lpspi.c
@@ -89,6 +89,7 @@ struct fsl_lpspi_data {
 	void (*rx)(struct fsl_lpspi_data *);
 
 	u32 remain;
+	u8 watermark;
 	u8 txfifosize;
 	u8 rxfifosize;
 
@@ -235,7 +236,7 @@ static void fsl_lpspi_set_watermark(struct fsl_lpspi_data *fsl_lpspi)
 {
 	u32 temp;
 
-	temp = fsl_lpspi->txfifosize >> 1 | (fsl_lpspi->rxfifosize >> 1) << 16;
+	temp = fsl_lpspi->watermark >> 1 | (fsl_lpspi->watermark >> 1) << 16;
 
 	writel(temp, fsl_lpspi->base + IMX7ULP_FCR);
 
@@ -261,7 +262,8 @@ static int fsl_lpspi_set_bitrate(struct fsl_lpspi_data *fsl_lpspi)
 	if (prescale == 8 && scldiv >= 256)
 		return -EINVAL;
 
-	writel(scldiv, fsl_lpspi->base + IMX7ULP_CCR);
+	writel(scldiv | (scldiv << 8) | ((scldiv >> 1) << 16),
+					fsl_lpspi->base + IMX7ULP_CCR);
 
 	dev_dbg(fsl_lpspi->dev, "perclk=%d, speed=%d, prescale =%d, scldiv=%d\n",
 		perclk_rate, config.speed_hz, prescale, scldiv);
@@ -329,6 +331,11 @@ static void fsl_lpspi_setup_transfer(struct spi_device *spi,
 		fsl_lpspi->tx = fsl_lpspi_buf_tx_u32;
 	}
 
+	if (t->len <= fsl_lpspi->txfifosize)
+		fsl_lpspi->watermark = t->len;
+	else
+		fsl_lpspi->watermark = fsl_lpspi->txfifosize;
+
 	fsl_lpspi_config(fsl_lpspi);
 }