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Groups > linux.kernel > #1444889
| From | Guenter Roeck <linux@roeck-us.net> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [v2,1/4] hwmon: iio_hwmon: defer probe when no channel is found |
| Date | 2016-07-16 19:10 +0200 |
| Message-ID | <rVBgd-6xd-7@gated-at.bofh.it> (permalink) |
| References | <rV8ee-5Bf-33@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Fri, Jul 15, 2016 at 11:59:11AM +0200, Quentin Schulz wrote:
> iio_channel_get_all returns -ENODEV when it cannot find either phandles and
> properties in the Device Tree or channels whose consumer_dev_name matches
> iio_hwmon in iio_map_list. The iio_map_list is filled in by iio drivers
> which might be probed after iio_hwmon.
>
> It is better to defer the probe of iio_hwmon if such error is returned by
> iio_channel_get_all in order to let a chance to iio drivers to expose
> channels in iio_map_list.
>
> Signed-off-by: Quentin Schulz <quentin.schulz@free-electrons.com>
> ---
>
> No modifications for this patch since we did not settled for a solution.
> What should we do?
>
AFAICS the only thing we can do is to replace module_platform_driver() with
its explicitly coded variant, and to use use late_initcall() instead of
module_init(). Anything else would result in endless probe deferrals if
there are no channels.
Guenter
> drivers/hwmon/iio_hwmon.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/hwmon/iio_hwmon.c b/drivers/hwmon/iio_hwmon.c
> index b550ba5..c0da4d9 100644
> --- a/drivers/hwmon/iio_hwmon.c
> +++ b/drivers/hwmon/iio_hwmon.c
> @@ -73,8 +73,11 @@ static int iio_hwmon_probe(struct platform_device *pdev)
> name = dev->of_node->name;
>
> channels = iio_channel_get_all(dev);
> - if (IS_ERR(channels))
> + if (IS_ERR(channels)) {
> + if (PTR_ERR(channels) == -ENODEV)
> + return -EPROBE_DEFER;
> return PTR_ERR(channels);
> + }
>
> st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
> if (st == NULL) {
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[PATCH v2 0/4] add support for Allwinner SoCs ADC Quentin Schulz <quentin.schulz@free-electrons.com> - 2016-07-15 12:10 +0200
[PATCH v2 3/4] mfd: add support for Allwinner SoCs ADC Quentin Schulz <quentin.schulz@free-electrons.com> - 2016-07-15 12:10 +0200
Re: [PATCH v2 3/4] mfd: add support for Allwinner SoCs ADC Maxime Ripard <maxime.ripard@free-electrons.com> - 2016-07-18 15:10 +0200
Re: [PATCH v2 3/4] mfd: add support for Allwinner SoCs ADC Quentin Schulz <quentin.schulz@free-electrons.com> - 2016-07-19 14:10 +0200
Re: [PATCH v2 3/4] mfd: add support for Allwinner SoCs ADC Jonathan Cameron <jic23@kernel.org> - 2016-07-19 07:40 +0200
Re: [PATCH v2 3/4] mfd: add support for Allwinner SoCs ADC Lee Jones <lee.jones@linaro.org> - 2016-07-19 09:40 +0200
Re: [PATCH v2 3/4] mfd: add support for Allwinner SoCs ADC Jonathan Cameron <jic23@kernel.org> - 2016-07-20 17:10 +0200
Re: [PATCH v2 3/4] mfd: add support for Allwinner SoCs ADC Lee Jones <lee.jones@linaro.org> - 2016-07-21 14:20 +0200
Re: [PATCH v2 3/4] mfd: add support for Allwinner SoCs ADC Maxime Ripard <maxime.ripard@free-electrons.com> - 2016-07-21 22:10 +0200
Re: [PATCH v2 3/4] mfd: add support for Allwinner SoCs ADC Lee Jones <lee.jones@linaro.org> - 2016-07-22 16:00 +0200
Re: [PATCH v2 3/4] mfd: add support for Allwinner SoCs ADC Jonathan Cameron <jic23@kernel.org> - 2016-07-23 13:00 +0200
Re: [PATCH v2 3/4] mfd: add support for Allwinner SoCs ADC Maxime Ripard <maxime.ripard@free-electrons.com> - 2016-07-25 12:00 +0200
Re: [PATCH v2 3/4] mfd: add support for Allwinner SoCs ADC Quentin Schulz <quentin.schulz@free-electrons.com> - 2016-07-19 10:40 +0200
[PATCH v2 1/4] hwmon: iio_hwmon: defer probe when no channel is found Quentin Schulz <quentin.schulz@free-electrons.com> - 2016-07-15 12:10 +0200
Re: [v2,1/4] hwmon: iio_hwmon: defer probe when no channel is found Guenter Roeck <linux@roeck-us.net> - 2016-07-16 19:10 +0200
Re: [v2,1/4] hwmon: iio_hwmon: defer probe when no channel is found Maxime Ripard <maxime.ripard@free-electrons.com> - 2016-07-18 12:10 +0200
Re: [v2,1/4] hwmon: iio_hwmon: defer probe when no channel is found Guenter Roeck <linux@roeck-us.net> - 2016-07-18 15:30 +0200
[PATCH v2 4/4] hwmon: iio: add label for channels read by iio_hwmon Quentin Schulz <quentin.schulz@free-electrons.com> - 2016-07-15 12:10 +0200
Re: [PATCH v2 4/4] hwmon: iio: add label for channels read by iio_hwmon Guenter Roeck <linux@roeck-us.net> - 2016-07-15 16:10 +0200
Re: [PATCH v2 4/4] hwmon: iio: add label for channels read by iio_hwmon Quentin Schulz <quentin.schulz@free-electrons.com> - 2016-07-15 16:40 +0200
Re: [PATCH v2 4/4] hwmon: iio: add label for channels read by iio_hwmon Guenter Roeck <linux@roeck-us.net> - 2016-07-16 05:00 +0200
Re: [PATCH v2 4/4] hwmon: iio: add label for channels read by iio_hwmon Jonathan Cameron <jic23@kernel.org> - 2016-07-19 07:40 +0200
Re: [PATCH v2 4/4] hwmon: iio: add label for channels read by iio_hwmon Quentin Schulz <quentin.schulz@free-electrons.com> - 2016-07-19 09:00 +0200
Re: [PATCH v2 4/4] hwmon: iio: add label for channels read by iio_hwmon Jonathan Cameron <jic23@kernel.org> - 2016-07-20 16:50 +0200
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