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SubjectRe: [PATCH 2/5] i2c-mux-gpio: Return an error if no config data found
On Thu, Apr 25, 2019 at 07:28:52PM +0000, Peter Rosin wrote:
> On 2019-04-25 17:47, Serge Semin wrote:
> > On Wed, Apr 24, 2019 at 09:25:50PM +0000, Peter Rosin wrote:
> >> On 2019-04-24 14:34, Serge Semin wrote:
> >>> It's pointless and might be even errors prone to proceed with further
> >>> initialization if neither of- no platform-based settings were discovered.
> >>> Just return an error in this case.
> >>>
> >>> Signed-off-by: Serge Semin <fancer.lancer@gmail.com>
> >>> ---
> >>> drivers/i2c/muxes/i2c-mux-gpio.c | 12 +++++++-----
> >>> 1 file changed, 7 insertions(+), 5 deletions(-)
> >>>
> >>> diff --git a/drivers/i2c/muxes/i2c-mux-gpio.c b/drivers/i2c/muxes/i2c-mux-gpio.c
> >>> index 24cf6ec02e75..a14fe132b0c3 100644
> >>> --- a/drivers/i2c/muxes/i2c-mux-gpio.c
> >>> +++ b/drivers/i2c/muxes/i2c-mux-gpio.c
> >>> @@ -132,7 +132,7 @@ static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
> >>> static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
> >>> struct platform_device *pdev)
> >>> {
> >>> - return 0;
> >>> + return -EINVAL;
> >>> }
> >>> #endif
> >>>
> >>> @@ -142,6 +142,9 @@ static int i2c_mux_gpio_probe_plat(struct gpiomux *mux,
> >>> struct i2c_mux_gpio_platform_data *data = dev_get_platdata(&pdev->dev);
> >>> struct gpio_chip *gpio;
> >>>
> >>> + if (!data)
> >>> + return -EINVAL;
> >>> +
> >>> /*
> >>> * If a GPIO chip name is provided, the GPIO pin numbers provided are
> >>> * relative to its base GPIO number. Otherwise they are absolute.
> >>> @@ -175,11 +178,10 @@ static int i2c_mux_gpio_probe(struct platform_device *pdev)
> >>> if (!mux)
> >>> return -ENOMEM;
> >>>
> >>> - if (!dev_get_platdata(&pdev->dev))
> >>> + ret = i2c_mux_gpio_probe_plat(mux, pdev);
> >>> + if (ret)
> >>> ret = i2c_mux_gpio_probe_dt(mux, pdev);
> >>> - else
> >>> - ret = i2c_mux_gpio_probe_plat(mux, pdev);
> >>> - if (ret < 0)
> >>> + if (ret)
> >>> return ret;
> >>
> >> I notice that after this patch, all probe failures from non-dt configs
> >> will return -EINVAL from the dummy i2c_mux_gpio_probe_dt that gets
> >> called on i2c_mux_gpio_probe_plat failure.
> >>
> >> So, any -EPROBE_DEFER is now lost. That probably doesn't fly.
> >>
> >
> > So what do you suggest then?
>
> I don't know, I'm just pointing out that you are breaking probe-defer.
>
> > We can return to something like:
> > if (dev_get_platdata(&pdev->dev))
> > ret = i2c_mux_gpio_probe_plat(mux, pdev);
> > else
> > ret = i2c_mux_gpio_probe_dt(mux, pdev);
> >
> > In this case there is no falling back to dt. Just either plat- or of-based
> > initialization. The same can be done for i2c_mux_gpio_request_*() methods.
>
> Works for me, I fail to see why it is interesting with a fallback
> anyway? If you supply platform data, that is supposed to take
> precedence. No?
>
> If the platform data fails, I'd rather not have the code run into the
> weeds attempting stuff that's not even supposed to work...
>

Yeah, you are right. Adding fallback pattern here was a bad idea.
I'll fix it in the next patchset version.

-Sergey

> Cheers,
> Peter
>
> > -Sergey
> >
> >> Cheers,
> >> Peter
> >>
> >>>
> >>> parent = i2c_get_adapter(mux->data.parent);
> >>>
> >>
>

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