From: Frieder Schrempf frieder.schrempf@kontron.de
[ Upstream commit db2d2dc9a0b58c6faefb6b002fdbed4f0362d1a4 ]
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: 6fd8b8503a0d ("spi: spi-imx: Fix out-of-order CS/SCLK operation at low speeds") Fixes: 07e759387788 ("spi: spi-imx: add PIO polling support") Cc: Marc Kleine-Budde mkl@pengutronix.de Cc: David Jander david@protonic.nl Cc: Fabio Estevam festevam@gmail.com Cc: Mark Brown broonie@kernel.org Cc: Marek Vasut marex@denx.de Cc: stable@vger.kernel.org Signed-off-by: Frieder Schrempf frieder.schrempf@kontron.de Tested-by: Fabio Estevam festevam@gmail.com Acked-by: Marek Vasut marex@denx.de Link: https://lore.kernel.org/r/20221115181002.2068270-1-frieder@fris.de Signed-off-by: Mark Brown broonie@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 0e3bc0b0a526..74b3b6ca15ef 100644 --- a/drivers/spi/spi-imx.c +++ b/drivers/spi/spi-imx.c @@ -434,8 +434,7 @@ 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)