On Mon, Jun 08, 2015 at 07:48:25PM -0600, Stephen Warren wrote: > On 06/06/2015 12:18 PM, Silvan Wicki wrote: > > Adds: make sure bits 16-31 of DIV register are always 0 > > Adds: assume minimal divider of 2 if divider resulted in 0 > > (bcm2835 sets divider to 32768 if cdiv is set to 0) > > > > See page 33/34 of BCM2835-ARM-Peripherals.pdf for the DIV register. > > https://www.raspberrypi.org/wp-content/uploads/2012/02/BCM2835-ARM-Peripherals.pdf > > > diff --git a/drivers/i2c/busses/i2c-bcm2835.c b/drivers/i2c/busses/i2c-bcm2835.c > > > @@ -252,12 +255,28 @@ static int bcm2835_i2c_probe(struct platform_device *pdev) > > > + if (divider > BCM2835_I2C_CDIV_MAX) { > > + dev_warn(&pdev->dev, > > + "Clock too slow, falling back to min clock speed\n"); > > + divider = BCM2835_I2C_CDIV_MAX; > > + } > > bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DIV, divider); > > Shouldn't this be an error? i.e. dev_err() not dev_warn(), and return an > error code. > > If the divider that's required to reach the requested clock is higher > than the HW can implement, that means the actual clock will be faster > than the requested clock. Presumably there's a reason the specific slow > rate was requested, and if we exceed it, there will be problems. i searched for similar things in other i2c drivers and found that i2c-bcm-iproc, i2c-digicolor do a dev_err. so it seems like dev_err is the way it should be implemented. i'll update that. -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
