On Wed, 05 Jun 2019, Johan Hovold wrote: > On Wed, Jun 05, 2019 at 08:16:25AM +0100, Lee Jones wrote: > > On Tue, 04 Jun 2019, Bjorn Andersson wrote: > > > > > On Tue 04 Jun 03:44 PDT 2019, Lee Jones wrote: > > > > > > > The Qualcomm Geni I2C driver currently probes silently which can be > > > > confusing when debugging potential issues. Add a low level (INFO) > > > > print when each I2C controller is successfully initially set-up. > > > > > > > > Signed-off-by: Lee Jones <lee.jones@xxxxxxxxxx> > > > > --- > > > > drivers/i2c/busses/i2c-qcom-geni.c | 2 ++ > > > > 1 file changed, 2 insertions(+) > > > > > > > > diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/i2c-qcom-geni.c > > > > index 0fa93b448e8d..e27466d77767 100644 > > > > --- a/drivers/i2c/busses/i2c-qcom-geni.c > > > > +++ b/drivers/i2c/busses/i2c-qcom-geni.c > > > > @@ -598,6 +598,8 @@ static int geni_i2c_probe(struct platform_device *pdev) > > > > return ret; > > > > } > > > > > > > > + dev_info(&pdev->dev, "Geni-I2C adaptor successfully added\n"); > > > > + > > > > > > I would prefer that we do not add such prints, as it would be to accept > > > the downstream behaviour of spamming the log to the point where no one > > > will ever look through it. > > > > We should be able to find a middle ground. Spamming the log with all > > sorts of device specific information/debug is obviously not > > constructive, but a single liner to advertise that an important > > device/controller has been successfully initialised is more helpful > > than it is hinderous. > > > > This print was added due to the silent initialisation costing me > > several hours of debugging ACPI device/driver code (albeit learning a > > lot about ACPI as I go) just to find out that it was already doing the > > right thing - just very quietly. > > No, we don't add noise like this to the logs just because it may be > useful while debugging. Even one-liners add up. One line per device is should not cause an issue. Problems occur when developers try to print all kinds of device specifics to the boot log. A simple, single line for such an important device/controller has more benefits than drawbacks. > There are plenty of options for debugging already ranging from adding a > temporary dev_info() to the probe function in question to using dynamic > debugging to have driver core log every successful probe. This is what I ended up doing. It was time consuming to parse though a log of that size when you have no paging or keyboard. > And in this case you say the driver was in fact already bound; that can > easily be verified through sysfs too in case things aren't behaving the > way you expect. Not in a non-booting system with no keyboard you can't. ;) -- Lee Jones [李琼斯] Linaro Services Technical Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog
