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From: Guenter Roeck <linux@roeck-us.net>
To: "Enrico Weigelt,
	metux IT consult" <weigelt-d/C+FbuhHiA@public.gmane.org>,
	Chris Packham
	<Chris.Packham-6g8wRflRTwXFdCa3tKVlE6U/zSkkHjvu@public.gmane.org>,
	"devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
	<devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Cc: "jdelvare-l3A5Bk7waGM@public.gmane.org"
	<jdelvare-l3A5Bk7waGM@public.gmane.org>,
	"lm-sensors-GZX6beZjE8VD60Wz+7aTrA@public.gmane.org"
	<lm-sensors-GZX6beZjE8VD60Wz+7aTrA@public.gmane.org>,
	"shardy-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org"
	<shardy-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	"guillaume.roguez-4ysUXcep3aM1wj+D4I0NRVaTQe2KTcn/@public.gmane.org"
	<guillaume.roguez-4ysUXcep3aM1wj+D4I0NRVaTQe2KTcn/@public.gmane.org>
Subject: Re: [lm-sensors] Dealing with optional i2c devices in a devicetree
Date: Mon, 08 Jun 2015 15:03:12 +0000	[thread overview]
Message-ID: <5575AEB0.70807@roeck-us.net> (raw)
In-Reply-To: <55758667.70501-d/C+FbuhHiA@public.gmane.org>

On 06/08/2015 05:11 AM, Enrico Weigelt, metux IT consult wrote:
> Am 08.06.2015 um 08:01 schrieb Chris Packham:
>
> Hi folks,
>
>  > Sounds like my best bet is to mark the nodes as disabled in the
>  > dts and have my bootloader update them on the way through.
>
> In case your bootloader can take that decision (eg. if the device
> is present at boot time, and the bootloader has the proper probing
> logic or simply knows the device has to be there), that would be
> an pretty easy way.
>
>
> But let me add another usecase, which might be a bit more tricky:
>
> Let's assume we can plug in some more complex device, which consists
> of several (pretty standard) subdevices, behind certain bus'es (maybe
> it's attached via USB, and somewhere behind are some I2C bus'es with
> regulators, pwm-generators, etc).
>
> Let's further assume, we already got some DTS or some piece of memory
> with an DTB subtree for that device (eg. some simple bulk endpoint that
> just gives back a bunch of bytes with the DTB).
>
> Now, when the device is plugged in, I'd like to get that piece of DTB
> loaded and the corresponding drivers initialized. And, of course, when
> it's plugged-out, everything should be shut down cleanly.
>
> How could we achieve that ?
>

Use devicetree overlays.

Guenter



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WARNING: multiple messages have this Message-ID (diff)
From: Guenter Roeck <linux-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>
To: "Enrico Weigelt,
	metux IT consult" <weigelt-d/C+FbuhHiA@public.gmane.org>,
	Chris Packham
	<Chris.Packham-6g8wRflRTwXFdCa3tKVlE6U/zSkkHjvu@public.gmane.org>,
	"devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
	<devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Cc: "jdelvare-l3A5Bk7waGM@public.gmane.org"
	<jdelvare-l3A5Bk7waGM@public.gmane.org>,
	"lm-sensors-GZX6beZjE8VD60Wz+7aTrA@public.gmane.org"
	<lm-sensors-GZX6beZjE8VD60Wz+7aTrA@public.gmane.org>,
	"shardy-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org"
	<shardy-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	"guillaume.roguez-4ysUXcep3aM1wj+D4I0NRVaTQe2KTcn/@public.gmane.org"
	<guillaume.roguez-4ysUXcep3aM1wj+D4I0NRVaTQe2KTcn/@public.gmane.org>
Subject: Re: Dealing with optional i2c devices in a devicetree
Date: Mon, 08 Jun 2015 08:03:12 -0700	[thread overview]
Message-ID: <5575AEB0.70807@roeck-us.net> (raw)
In-Reply-To: <55758667.70501-d/C+FbuhHiA@public.gmane.org>

On 06/08/2015 05:11 AM, Enrico Weigelt, metux IT consult wrote:
> Am 08.06.2015 um 08:01 schrieb Chris Packham:
>
> Hi folks,
>
>  > Sounds like my best bet is to mark the nodes as disabled in the
>  > dts and have my bootloader update them on the way through.
>
> In case your bootloader can take that decision (eg. if the device
> is present at boot time, and the bootloader has the proper probing
> logic or simply knows the device has to be there), that would be
> an pretty easy way.
>
>
> But let me add another usecase, which might be a bit more tricky:
>
> Let's assume we can plug in some more complex device, which consists
> of several (pretty standard) subdevices, behind certain bus'es (maybe
> it's attached via USB, and somewhere behind are some I2C bus'es with
> regulators, pwm-generators, etc).
>
> Let's further assume, we already got some DTS or some piece of memory
> with an DTB subtree for that device (eg. some simple bulk endpoint that
> just gives back a bunch of bytes with the DTB).
>
> Now, when the device is plugged in, I'd like to get that piece of DTB
> loaded and the corresponding drivers initialized. And, of course, when
> it's plugged-out, everything should be shut down cleanly.
>
> How could we achieve that ?
>

Use devicetree overlays.

Guenter


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  parent reply	other threads:[~2015-06-08 15:03 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-06-05  6:03 [lm-sensors] Dealing with optional i2c devices in a devicetree Chris Packham
2015-06-05  6:03 ` Chris Packham
     [not found] ` <55713BB1.80004-6g8wRflRTwXFdCa3tKVlE6U/zSkkHjvu@public.gmane.org>
2015-06-05  7:26   ` [lm-sensors] " Arnd Bergmann
2015-06-05  7:26     ` Arnd Bergmann
2015-06-08  6:01     ` [lm-sensors] " Chris Packham
2015-06-08  6:01       ` Chris Packham
2015-06-05  7:30   ` [lm-sensors] " Guenter Roeck
2015-06-05  7:30     ` Guenter Roeck
     [not found]     ` <55714FFB.3000608-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>
2015-06-08  6:01       ` [lm-sensors] " Chris Packham
2015-06-08  6:01         ` Chris Packham
     [not found]         ` <55752FD4.6050700-6g8wRflRTwXFdCa3tKVlE6U/zSkkHjvu@public.gmane.org>
2015-06-08 12:11           ` [lm-sensors] " Enrico Weigelt, metux IT consult
2015-06-08 12:11             ` Enrico Weigelt, metux IT consult
     [not found]             ` <55758667.70501-d/C+FbuhHiA@public.gmane.org>
2015-06-08 15:03               ` Guenter Roeck [this message]
2015-06-08 15:03                 ` Guenter Roeck
2015-06-05  8:06   ` [lm-sensors] " Jean Delvare
2015-06-05  8:06     ` Jean Delvare

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