Patch "spi: lpspi: add the error info of transfer speed setting" 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: add the error info of transfer speed setting

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-add-the-error-info-of-transfer-speed-setti.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 cf722d480a821551eaf48d68c2ee45ea698b1b0d
Author: Clark Wang <xiaoning.wang@xxxxxxx>
Date:   Wed Mar 6 06:30:41 2019 +0000

    spi: lpspi: add the error info of transfer speed setting
    
    [ Upstream commit 77736a98b859e2c64aebbd0f90b2ce4b17682396 ]
    
    Add a error info when set a speed which greater than half of per-clk of
    spi module.
    
    The minimum SCK period is 2 cycles(CCR[SCKDIV]). So the maximum transfer
    speed is half of spi per-clk.
    
    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 5802f188051b8..8e1f6ee0a7993 100644
--- a/drivers/spi/spi-fsl-lpspi.c
+++ b/drivers/spi/spi-fsl-lpspi.c
@@ -263,6 +263,13 @@ static int fsl_lpspi_set_bitrate(struct fsl_lpspi_data *fsl_lpspi)
 	u8 prescale;
 
 	perclk_rate = clk_get_rate(fsl_lpspi->clk_per);
+
+	if (config.speed_hz > perclk_rate / 2) {
+		dev_err(fsl_lpspi->dev,
+		      "per-clk should be at least two times of transfer speed");
+		return -EINVAL;
+	}
+
 	for (prescale = 0; prescale < 8; prescale++) {
 		scldiv = perclk_rate /
 			 (clkdivs[prescale] * config.speed_hz) - 2;
@@ -316,7 +323,7 @@ static int fsl_lpspi_config(struct fsl_lpspi_data *fsl_lpspi)
 	return 0;
 }
 
-static void fsl_lpspi_setup_transfer(struct spi_device *spi,
+static int fsl_lpspi_setup_transfer(struct spi_device *spi,
 				     struct spi_transfer *t)
 {
 	struct fsl_lpspi_data *fsl_lpspi =
@@ -349,7 +356,7 @@ static void fsl_lpspi_setup_transfer(struct spi_device *spi,
 	else
 		fsl_lpspi->watermark = fsl_lpspi->txfifosize;
 
-	fsl_lpspi_config(fsl_lpspi);
+	return fsl_lpspi_config(fsl_lpspi);
 }
 
 static int fsl_lpspi_slave_abort(struct spi_controller *controller)
@@ -428,7 +435,10 @@ static int fsl_lpspi_transfer_one_msg(struct spi_controller *controller,
 	msg->actual_length = 0;
 
 	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
-		fsl_lpspi_setup_transfer(spi, xfer);
+		ret = fsl_lpspi_setup_transfer(spi, xfer);
+		if (ret < 0)
+			goto complete;
+
 		fsl_lpspi_set_cmd(fsl_lpspi, is_first_xfer);
 
 		is_first_xfer = false;