This is a note to let you know that I've just added the patch titled spi: spi-cadence-quadspi: Fix division by zero warning to the 5.13-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-spi-cadence-quadspi-fix-division-by-zero-warning.patch and it can be found in the queue-5.13 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 8e7f9650f5d883bca7b0239529c1b704673abd38 Author: Yoshitaka Ikeda <ikeda@xxxxxxxxxxxx> Date: Thu Jul 15 16:21:32 2021 +0000 spi: spi-cadence-quadspi: Fix division by zero warning [ Upstream commit 55cef88bbf12f3bfbe5c2379a8868a034707e755 ] Fix below division by zero warning: - Added an if statement because buswidth can be zero, resulting in division by zero. - The modified code was based on another driver (atmel-quadspi). [ 0.795337] Division by zero in kernel. : [ 0.834051] [<807fd40c>] (__div0) from [<804e1acc>] (Ldiv0+0x8/0x10) [ 0.839097] [<805f0710>] (cqspi_exec_mem_op) from [<805edb4c>] (spi_mem_exec_op+0x3b0/0x3f8) Fixes: 7512eaf54190 ("spi: cadence-quadspi: Fix dummy cycle calculation when buswidth > 1") Signed-off-by: Yoshitaka Ikeda <ikeda@xxxxxxxxxxxx> Link: https://lore.kernel.org/r/ed989af6-da88-4e0b-9ed8-126db6cad2e4@xxxxxxxxxxxx Signed-off-by: Mark Brown <broonie@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/spi/spi-cadence-quadspi.c b/drivers/spi/spi-cadence-quadspi.c index 7a00346ff9b9..13d1f0ce618e 100644 --- a/drivers/spi/spi-cadence-quadspi.c +++ b/drivers/spi/spi-cadence-quadspi.c @@ -307,11 +307,13 @@ static unsigned int cqspi_calc_rdreg(struct cqspi_flash_pdata *f_pdata) static unsigned int cqspi_calc_dummy(const struct spi_mem_op *op, bool dtr) { - unsigned int dummy_clk; + unsigned int dummy_clk = 0; - dummy_clk = op->dummy.nbytes * (8 / op->dummy.buswidth); - if (dtr) - dummy_clk /= 2; + if (op->dummy.buswidth && op->dummy.nbytes) { + dummy_clk = op->dummy.nbytes * (8 / op->dummy.buswidth); + if (dtr) + dummy_clk /= 2; + } return dummy_clk; }