Patch "spi: Fixed division by zero warning" has been added to the 5.14-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

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

    spi: Fixed division by zero warning

to the 5.14-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-fixed-division-by-zero-warning.patch
and it can be found in the queue-5.14 subdirectory.

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



commit ef6a4901324313f06aea07f5864e088f3f96218e
Author: Yoshitaka Ikeda <ikeda@xxxxxxxxxxxx>
Date:   Wed Sep 8 05:29:12 2021 +0000

    spi: Fixed division by zero warning
    
    [ Upstream commit 09134c5322df9f105d9ed324051872d5d0e162aa ]
    
    The reason for dividing by zero is because the dummy bus width is zero,
    but if the dummy n bytes is zero, it indicates that there is no data transfer,
    so there is no need for calculation.
    
    Fixes: 7512eaf54190 ("spi: cadence-quadspi: Fix dummy cycle calculation when buswidth > 1")
    Signed-off-by: Yoshitaka Ikeda <ikeda@xxxxxxxxxxxx>
    Acked-by: Pratyush Yadav <p.yadav@xxxxxx>
    Link: https://lore.kernel.org/r/OSZPR01MB70049C8F56ED8902852DF97B8BD49@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
    Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/spi/atmel-quadspi.c b/drivers/spi/atmel-quadspi.c
index 95d4fa32c2995..92d9610df1fd8 100644
--- a/drivers/spi/atmel-quadspi.c
+++ b/drivers/spi/atmel-quadspi.c
@@ -310,7 +310,7 @@ static int atmel_qspi_set_cfg(struct atmel_qspi *aq,
 		return mode;
 	ifr |= atmel_qspi_modes[mode].config;
 
-	if (op->dummy.buswidth && op->dummy.nbytes)
+	if (op->dummy.nbytes)
 		dummy_cycles = op->dummy.nbytes * 8 / op->dummy.buswidth;
 
 	/*
diff --git a/drivers/spi/spi-bcm-qspi.c b/drivers/spi/spi-bcm-qspi.c
index ea1865c08fc22..151e154284bde 100644
--- a/drivers/spi/spi-bcm-qspi.c
+++ b/drivers/spi/spi-bcm-qspi.c
@@ -395,7 +395,8 @@ static int bcm_qspi_bspi_set_flex_mode(struct bcm_qspi *qspi,
 	if (addrlen == BSPI_ADDRLEN_4BYTES)
 		bpp = BSPI_BPP_ADDR_SELECT_MASK;
 
-	bpp |= (op->dummy.nbytes * 8) / op->dummy.buswidth;
+	if (op->dummy.nbytes)
+		bpp |= (op->dummy.nbytes * 8) / op->dummy.buswidth;
 
 	switch (width) {
 	case SPI_NBITS_SINGLE:
diff --git a/drivers/spi/spi-mtk-nor.c b/drivers/spi/spi-mtk-nor.c
index 41e7b341d2616..5c93730615f8d 100644
--- a/drivers/spi/spi-mtk-nor.c
+++ b/drivers/spi/spi-mtk-nor.c
@@ -160,7 +160,7 @@ static bool mtk_nor_match_read(const struct spi_mem_op *op)
 {
 	int dummy = 0;
 
-	if (op->dummy.buswidth)
+	if (op->dummy.nbytes)
 		dummy = op->dummy.nbytes * BITS_PER_BYTE / op->dummy.buswidth;
 
 	if ((op->data.buswidth == 2) || (op->data.buswidth == 4)) {
diff --git a/drivers/spi/spi-stm32-qspi.c b/drivers/spi/spi-stm32-qspi.c
index 27f35aa2d746d..514337c86d2c3 100644
--- a/drivers/spi/spi-stm32-qspi.c
+++ b/drivers/spi/spi-stm32-qspi.c
@@ -397,7 +397,7 @@ static int stm32_qspi_send(struct spi_mem *mem, const struct spi_mem_op *op)
 		ccr |= FIELD_PREP(CCR_ADSIZE_MASK, op->addr.nbytes - 1);
 	}
 
-	if (op->dummy.buswidth && op->dummy.nbytes)
+	if (op->dummy.nbytes)
 		ccr |= FIELD_PREP(CCR_DCYC_MASK,
 				  op->dummy.nbytes * 8 / op->dummy.buswidth);