| Message ID | 20190604104455.8877-2-lee.jones@linaro.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | None | expand |
On Wed, 5 Jun 2019 at 09:16, Lee Jones <lee.jones@linaro.org> 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@linaro.org> > > > --- > > > 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. > I agree. There are numerous EHCI drivers IIRC which, if compiled in, unconditionally print some blurb, whether you have the hardware or not, which is pretty annoying. In this case, however, having a single line per successfully probed device (containing the dev_name and perhaps the MMIO base address or some other identifying feature) is pretty useful, and shouldn't be regarded as log spamming imo. dev_info() honours the 'quiet' kernel command line parameter, and so you will only see the message if you actually look at the log.
On Wed, Jun 05, 2019 at 09:49:21AM +0100, Lee Jones wrote: > On Wed, 05 Jun 2019, Johan Hovold wrote: > > > On Wed, Jun 05, 2019 at 09:20:47AM +0100, Lee Jones wrote: > > > On Wed, 05 Jun 2019, Johan Hovold wrote: > > > > 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. > > > > With the right command-line option to enable dynamic debugging you get > > one line per successful probe, just like you wanted. Or are you now > > saying that one-line per device is too much after all? ;) > > Which command line option are you pertaining to? To enable dynamic debugging in driver core you could use something like CONFIG_CMDLINE="dyndbg=\"func really_probe =p\"" That gives you two printouts per successful probe, for example: bus: 'usb-serial': really_probe: probing driver edgeport_ti_1 with device ttyUSB0 bus: 'usb-serial': really_probe: bound device ttyUSB0 to driver edgeport_ti_1 Or you can of course just change the corresponding pr_debug to pr_info while debugging. Johan
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"); + return 0; }
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@linaro.org> --- drivers/i2c/busses/i2c-qcom-geni.c | 2 ++ 1 file changed, 2 insertions(+) -- 2.17.1