From 622a9f1ce0c53f661bd323fa3e3b071f5a3733b5 Mon Sep 17 00:00:00 2001 From: Alex Crawford Date: Fri, 28 Jan 2022 13:36:51 -0800 Subject: [PATCH] i2c: bcm2835: Make clock-stretch timeout configurable The default clock-stretch timeout is 35 mS, which works well for SMBus, but there are some I2C devices which can stretch the clock even longer. Rather than trying to prescribe a safe default for everyone, allow the timeout to be configured. Signed-off-by: Alex Crawford --- drivers/i2c/busses/i2c-bcm2835.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) --- a/drivers/i2c/busses/i2c-bcm2835.c +++ b/drivers/i2c/busses/i2c-bcm2835.c @@ -60,6 +60,10 @@ static unsigned int debug; module_param(debug, uint, 0644); MODULE_PARM_DESC(debug, "1=err, 2=isr, 3=xfer"); +static unsigned int clk_tout_ms = 35; /* SMBUs-recommended 35ms */ +module_param(clk_tout_ms, uint, 0644); +MODULE_PARM_DESC(clk_tout_ms, "clock-stretch timeout (mS)"); + #define BCM2835_DEBUG_MAX 512 struct bcm2835_debug { struct i2c_msg *msg; @@ -219,12 +223,12 @@ static int clk_bcm2835_i2c_set_rate(stru (redl << BCM2835_I2C_REDL_SHIFT)); /* - * Set the clock stretch timeout to the SMBUs-recommended 35ms. + * Set the clock stretch timeout. */ - if (rate > 0xffff*1000/35) + if (rate > 0xffff*1000/clk_tout_ms) clk_tout = 0xffff; else - clk_tout = 35*rate/1000; + clk_tout = clk_tout_ms*rate/1000; bcm2835_i2c_writel(div->i2c_dev, BCM2835_I2C_CLKT, clk_tout);