From 231d069fcde22bd0582c2c9564f1b334d280c7d7 Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Tue, 29 Aug 2017 14:08:35 +0200 Subject: [PATCH] i2c: designware: Round down ACPI provided clk to nearest supported clk The Lenovo Miix2 8 DSDT contains an i2c clk / bus speed of 1700000 Hz for one if its devices, which is not supported. This is the second DSDT to show up with an unsupported clk in a short time, remove the hardcoded fix for DSDTs with a 1 MiHz clock and simply always round down the clk to the nearest supported value. Reported-by: russianneuromancer@ya.ru Fixes: 682c6c2188 ("i2c: designware: Some broken DSTDs use 1MiHz ...") Signed-off-by: Hans de Goede Acked-by: Jarkko Nikula Signed-off-by: Wolfram Sang --- drivers/i2c/busses/i2c-designware-platdrv.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c index 57248bccadbc..2b98a173136f 100644 --- a/drivers/i2c/busses/i2c-designware-platdrv.c +++ b/drivers/i2c/busses/i2c-designware-platdrv.c @@ -256,7 +256,8 @@ static int dw_i2c_plat_probe(struct platform_device *pdev) struct dw_i2c_dev *dev; u32 acpi_speed, ht = 0; struct resource *mem; - int irq, ret; + int i, irq, ret; + const int supported_speeds[] = { 0, 100000, 400000, 1000000, 3400000 }; irq = platform_get_irq(pdev, 0); if (irq < 0) @@ -297,9 +298,16 @@ static int dw_i2c_plat_probe(struct platform_device *pdev) } acpi_speed = i2c_acpi_find_bus_speed(&pdev->dev); - /* Some broken DSTDs use 1MiHz instead of 1MHz */ - if (acpi_speed == 1048576) - acpi_speed = 1000000; + /* + * Some DSTDs use a non standard speed, round down to the lowest + * standard speed. + */ + for (i = 1; i < ARRAY_SIZE(supported_speeds); i++) { + if (acpi_speed < supported_speeds[i]) + break; + } + acpi_speed = supported_speeds[i - 1]; + /* * Find bus speed from the "clock-frequency" device property, ACPI * or by using fast mode if neither is set. -- 2.20.1