From ad05aa51dc82b40de835647c9d8a1f33170c1401 Mon Sep 17 00:00:00 2001 From: Frieder Schrempf Date: Tue, 15 Nov 2022 19:10:00 +0100 Subject: [PATCH] spi: spi-imx: Fix spi_bus_clk if requested clock is higher than input clock [ Upstream commit 88492dbafd21a14ac7c518a11c73f17f18418daa ] In case the requested bus clock is higher than the input clock, the correct dividers (pre = 0, post = 0) are returned from mx51_ecspi_clkdiv(), but *fres is left uninitialized and therefore contains an arbitrary value. This causes trouble for the recently introduced PIO polling feature as the value in spi_imx->spi_bus_clk is used there to calculate for which transfers to enable PIO polling. Fix this by setting *fres even if no clock dividers are in use. This issue was observed on Kontron BL i.MX8MM with an SPI peripheral clock set to 50 MHz by default and a requested SPI bus clock of 80 MHz for the SPI NOR flash. With the fix applied the debug message from mx51_ecspi_clkdiv() now prints the following: spi_imx 30820000.spi: mx51_ecspi_clkdiv: fin: 50000000, fspi: 50000000, post: 0, pre: 0 Fixes: 7bfbfe8ca965 ("spi: spi-imx: Fix out-of-order CS/SCLK operation at low speeds") Fixes: ffa85d09f4b6 ("spi: spi-imx: add PIO polling support") Cc: Marc Kleine-Budde Cc: David Jander Cc: Fabio Estevam Cc: Mark Brown Cc: Marek Vasut Cc: stable@vger.kernel.org Signed-off-by: Frieder Schrempf Tested-by: Fabio Estevam Acked-by: Marek Vasut Link: https://lore.kernel.org/r/20221115181002.2068270-1-frieder@fris.de Signed-off-by: Mark Brown Signed-off-by: Sasha Levin --- drivers/spi/spi-imx.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c index 474d5a7fa95e3..9d593675257e0 100644 --- a/drivers/spi/spi-imx.c +++ b/drivers/spi/spi-imx.c @@ -431,8 +431,7 @@ static unsigned int mx51_ecspi_clkdiv(struct spi_imx_data *spi_imx, unsigned int pre, post; unsigned int fin = spi_imx->spi_clk; - if (unlikely(fspi > fin)) - return 0; + fspi = min(fspi, fin); post = fls(fin) - fls(fspi); if (fin > fspi << post) -- 2.39.5