On 20/01/2022 18:35:48-0500, Hugo Villeneuve wrote:
> On Wed, 19 Jan 2022 20:10:20 +0100
> Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx> wrote:
>
> > On 19/01/2022 13:08:45-0500, Hugo Villeneuve wrote:
> > > On Wed, 19 Jan 2022 18:37:40 +0100
> > > Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx> wrote:
> > >
> > > > On 19/01/2022 12:27:39-0500, Hugo Villeneuve wrote:
> > > > > From: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx>
> > > > >
> > > > > If writing to CLKOUT register fails, the probe operation will be aborted
> > > > > without a meaningful error message.
> > > > >
> > > >
> > > > The current trend is to remove debug messages, please do not add more :)
> > >
> > > Hi,
> > > If the read operation fails, the probe function will exit silently, and our RTC chip will not work. In that case, if we parse the dmesg logs, I think we should have an indication that something went wrong.
> > >
> >
> > This is not true, it doesn't fail silently, you'd get:
> > rtc-pcf2127: probe of 1-0051 failed with error -121
>
> Well this is certainly true for me because I am not seing the same error message as you :)
>
> Just for context, I have defined a dummy pcf2127 on I2C bus 0 in my device tree (no actual hardware is present). I also added some debug messages to investigate (rtc-pcf2127.c and dd.c files), and here is the dmesg log after issuing "modprobe rtc-pcf2127":
>
> [Thu Jan 20 23:22:20 2022] rtc-pcf2127-i2c 0-0051: pcf2127_i2c_probe
> [Thu Jan 20 23:22:20 2022] rtc-pcf2127-i2c 0-0051: pcf2127_probe
> [Thu Jan 20 23:22:20 2022] rtc-pcf2127-i2c 0-0051: PORO disabling failed with error -6
> [Thu Jan 20 23:22:20 2022] rtc-pcf2127-i2c 0-0051: call_driver_probe probe error: -6
>
> Error code -6 is -ENXIO, and looking at the call_driver_probe() function in dd.c, I now understand why I didn't see the error message (line 531):
>
> case -ENXIO:
> pr_debug("%s: probe of %s rejects match %d\n",
> drv->name, dev_name(dev), ret);
>
> So it seems that the return code is different than what you got?
>
Probably because we don't have the same i2c controller and the driver
for mine is returning -EREMOTEIO when the device is not present.
--
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
