From 23cdddb21f41e6092643fb8403f992f99ade33be Mon Sep 17 00:00:00 2001 From: Jarkko Nikula Date: Fri, 28 Jun 2019 17:07:17 +0300 Subject: [PATCH] spi: pxa2xx: Set minimum transfer speed It is possible to request a transfer with a speed lower than supported by the HW. This causes silent divider calculation underflow in ssp_get_clk_div() which leads to a frequency higher than requested. Up to maximum speed of the controller. Set the minimum supported transfer speed and let the SPI core to validate no transfers have speed lower than supported. Signed-off-by: Jarkko Nikula Signed-off-by: Mark Brown --- drivers/spi/spi-pxa2xx.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/spi/spi-pxa2xx.c b/drivers/spi/spi-pxa2xx.c index af3f37ba82c8..259c20f7a542 100644 --- a/drivers/spi/spi-pxa2xx.c +++ b/drivers/spi/spi-pxa2xx.c @@ -1704,6 +1704,16 @@ static int pxa2xx_spi_probe(struct platform_device *pdev) goto out_error_dma_irq_alloc; controller->max_speed_hz = clk_get_rate(ssp->clk); + /* + * Set minimum speed for all other platforms than Intel Quark which is + * able do under 1 Hz transfers. + */ + if (!pxa25x_ssp_comp(drv_data)) + controller->min_speed_hz = + DIV_ROUND_UP(controller->max_speed_hz, 4096); + else if (!is_quark_x1000_ssp(drv_data)) + controller->min_speed_hz = + DIV_ROUND_UP(controller->max_speed_hz, 512); /* Load default SSP configuration */ pxa2xx_spi_write(drv_data, SSCR0, 0);