[PATCH/RFC] kbuild: Create a rule for building device tree overlay objects

[PATCH/RFC] kbuild: Create a rule for building device tree overlay objects

[Geert Uytterhoeven]

This allows to handle device tree overlays like plain device trees.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
Questions:
  - Do we want dtso files under arch/<arch>/boot/dts/, too?
  - Do we want to move the dts files outside the kernel repository
    first?

 scripts/Makefile.lib | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 79e86613712f2230..4b14eef1d4b2ce8f 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -292,6 +292,9 @@ cmd_dtc = mkdir -p $(dir ${dtc-tmp}) ; \
 $(obj)/%.dtb: $(src)/%.dts FORCE
 	$(call if_changed_dep,dtc)
 
+$(obj)/%.dtbo: $(src)/%.dtso FORCE
+	$(call if_changed_dep,dtc)
+
 dtc-tmp = $(subst $(comma),_,$(dot-target).dts.tmp)
 
 # Bzip2
-- 
1.9.1

Re: [PATCH/RFC] kbuild: Create a rule for building device tree overlay objects

[Pantelis Antoniou]

Hi Geert,

> On May 12, 2015, at 14:56 , Geert Uytterhoeven <geert+renesas@glider.be> wrote:
> 
> This allows to handle device tree overlays like plain device trees.
> 
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> ---
> Questions:
>  - Do we want dtso files under arch/<arch>/boot/dts/, too?
>  - Do we want to move the dts files outside the kernel repository
>    first?
> 

Oh that’s a nice hornet’s nest you’ve kicked here.

arch/<arch>/boot/dts should not be the place, cause overlays are not related with boot per se.
As they are right now are board (family) specific.

I think we should try to keep an external kernel repo with them for now until we
figure out where to put them.

> scripts/Makefile.lib | 3 +++
> 1 file changed, 3 insertions(+)
> 
> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
> index 79e86613712f2230..4b14eef1d4b2ce8f 100644
> --- a/scripts/Makefile.lib
> +++ b/scripts/Makefile.lib
> @@ -292,6 +292,9 @@ cmd_dtc = mkdir -p $(dir ${dtc-tmp}) ; \
> $(obj)/%.dtb: $(src)/%.dts FORCE
> 	$(call if_changed_dep,dtc)
> 
> +$(obj)/%.dtbo: $(src)/%.dtso FORCE
> +	$(call if_changed_dep,dtc)
> +
> dtc-tmp = $(subst $(comma),_,$(dot-target).dts.tmp)
> 
> # Bzip2
> -- 
> 1.9.1

Regards

— Pantelis

--
To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH/RFC] kbuild: Create a rule for building device tree overlay objects

[Frank Rowand]

On 5/12/2015 7:33 AM, Pantelis Antoniou wrote:
> Hi Geert,
> 
>> On May 12, 2015, at 14:56 , Geert Uytterhoeven <geert+renesas@glider.be> wrote:
>>
>> This allows to handle device tree overlays like plain device trees.
>>
>> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
>> ---
>> Questions:
>>  - Do we want dtso files under arch/<arch>/boot/dts/, too?
>>  - Do we want to move the dts files outside the kernel repository
>>    first?
>>
> 
> Oh that’s a nice hornet’s nest you’ve kicked here.
> 
> arch/<arch>/boot/dts should not be the place, cause overlays are not related with boot per se.
> As they are right now are board (family) specific.

Aren't overlays meant to describe child boards (capes, shields, whatever) that may
vary from system to system, but are not expected to be hot-plugged while the OS
is up?  Or is hot-plug a design goal?

If no hot-plug, then to me an overlay is just as related to boot as the base dts.
It is a mere implementation detail that overlays are "loaded" from userspace
instead of by the booting kernel (I don't really know the details of using
overlays, so please correct me if I am wrong about how the kernel becomes aware
of an overlay).

> 
> I think we should try to keep an external kernel repo with them for now until we
> figure out where to put them.
> 
>> scripts/Makefile.lib | 3 +++
>> 1 file changed, 3 insertions(+)
>>
>> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
>> index 79e86613712f2230..4b14eef1d4b2ce8f 100644
>> --- a/scripts/Makefile.lib
>> +++ b/scripts/Makefile.lib
>> @@ -292,6 +292,9 @@ cmd_dtc = mkdir -p $(dir ${dtc-tmp}) ; \
>> $(obj)/%.dtb: $(src)/%.dts FORCE
>> 	$(call if_changed_dep,dtc)
>>
>> +$(obj)/%.dtbo: $(src)/%.dtso FORCE
>> +	$(call if_changed_dep,dtc)
>> +
>> dtc-tmp = $(subst $(comma),_,$(dot-target).dts.tmp)
>>
>> # Bzip2
>> -- 
>> 1.9.1
> 
> Regards
> 
> — Pantelis
> 
> --
> To unsubscribe from this list: send the line "unsubscribe devicetree" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 

--
To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH/RFC] kbuild: Create a rule for building device tree overlay objects

[Frank Rowand]

On 5/15/2015 5:47 PM, Frank Rowand wrote:
> On 5/12/2015 7:33 AM, Pantelis Antoniou wrote:
>> Hi Geert,
>>
>>> On May 12, 2015, at 14:56 , Geert Uytterhoeven <geert+renesas@glider.be> wrote:
>>>
>>> This allows to handle device tree overlays like plain device trees.
>>>
>>> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
>>> ---
>>> Questions:
>>>  - Do we want dtso files under arch/<arch>/boot/dts/, too?
>>>  - Do we want to move the dts files outside the kernel repository
>>>    first?
>>>
>>
>> Oh that’s a nice hornet’s nest you’ve kicked here.
>>
>> arch/<arch>/boot/dts should not be the place, cause overlays are not related with boot per se.
>> As they are right now are board (family) specific.
> 
> Aren't overlays meant to describe child boards (capes, shields, whatever) that may
> vary from system to system, but are not expected to be hot-plugged while the OS
> is up?  Or is hot-plug a design goal?

To reply to myself, there is a current discussion about whether to use overlays to
help with a powerpc pci desire to add and delete subtrees:

   http://www.spinics.net/lists/linux-pci/msg40740.html

That sound like hot-plug to me...

> 
> If no hot-plug, then to me an overlay is just as related to boot as the base dts.
> It is a mere implementation detail that overlays are "loaded" from userspace
> instead of by the booting kernel (I don't really know the details of using
> overlays, so please correct me if I am wrong about how the kernel becomes aware
> of an overlay).
> 
>>
>> I think we should try to keep an external kernel repo with them for now until we
>> figure out where to put them.
>>
>>> scripts/Makefile.lib | 3 +++
>>> 1 file changed, 3 insertions(+)
>>>
>>> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
>>> index 79e86613712f2230..4b14eef1d4b2ce8f 100644
>>> --- a/scripts/Makefile.lib
>>> +++ b/scripts/Makefile.lib
>>> @@ -292,6 +292,9 @@ cmd_dtc = mkdir -p $(dir ${dtc-tmp}) ; \
>>> $(obj)/%.dtb: $(src)/%.dts FORCE
>>> 	$(call if_changed_dep,dtc)
>>>
>>> +$(obj)/%.dtbo: $(src)/%.dtso FORCE
>>> +	$(call if_changed_dep,dtc)
>>> +
>>> dtc-tmp = $(subst $(comma),_,$(dot-target).dts.tmp)
>>>
>>> # Bzip2
>>> -- 
>>> 1.9.1
>>
>> Regards
>>
>> — Pantelis
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe devicetree" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>
> 
> 

--
To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH/RFC] kbuild: Create a rule for building device tree overlay objects

[Pantelis Antoniou]

Hi Frank,

> On May 16, 2015, at 05:16 , Frank Rowand <frowand.list@gmail.com> wrote:
> 
> On 5/15/2015 5:47 PM, Frank Rowand wrote:
>> On 5/12/2015 7:33 AM, Pantelis Antoniou wrote:
>>> Hi Geert,
>>> 
>>>> On May 12, 2015, at 14:56 , Geert Uytterhoeven <geert+renesas@glider.be> wrote:
>>>> 
>>>> This allows to handle device tree overlays like plain device trees.
>>>> 
>>>> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
>>>> ---
>>>> Questions:
>>>> - Do we want dtso files under arch/<arch>/boot/dts/, too?
>>>> - Do we want to move the dts files outside the kernel repository
>>>>   first?
>>>> 
>>> 
>>> Oh that’s a nice hornet’s nest you’ve kicked here.
>>> 
>>> arch/<arch>/boot/dts should not be the place, cause overlays are not related with boot per se.
>>> As they are right now are board (family) specific.
>> 
>> Aren't overlays meant to describe child boards (capes, shields, whatever) that may
>> vary from system to system, but are not expected to be hot-plugged while the OS
>> is up?  Or is hot-plug a design goal?
> 
> To reply to myself, there is a current discussion about whether to use overlays to
> help with a powerpc pci desire to add and delete subtrees:
> 
>   http://www.spinics.net/lists/linux-pci/msg40740.html
> 
> That sound like hot-plug to me…
> 

Many people asked for overlays with hot-plugging probably busses like PCI and USB.

Think about an FPGA on a PCI board that needs to be instantiated after insertion.

Expect more activity on that particular front; probably this week.

>> 
>> If no hot-plug, then to me an overlay is just as related to boot as the base dts.
>> It is a mere implementation detail that overlays are "loaded" from userspace
>> instead of by the booting kernel (I don't really know the details of using
>> overlays, so please correct me if I am wrong about how the kernel becomes aware
>> of an overlay).
>> 
>>> 
>>> I think we should try to keep an external kernel repo with them for now until we
>>> figure out where to put them.
>>> 
>>>> scripts/Makefile.lib | 3 +++
>>>> 1 file changed, 3 insertions(+)
>>>> 
>>>> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
>>>> index 79e86613712f2230..4b14eef1d4b2ce8f 100644
>>>> --- a/scripts/Makefile.lib
>>>> +++ b/scripts/Makefile.lib
>>>> @@ -292,6 +292,9 @@ cmd_dtc = mkdir -p $(dir ${dtc-tmp}) ; \
>>>> $(obj)/%.dtb: $(src)/%.dts FORCE
>>>> 	$(call if_changed_dep,dtc)
>>>> 
>>>> +$(obj)/%.dtbo: $(src)/%.dtso FORCE
>>>> +	$(call if_changed_dep,dtc)
>>>> +
>>>> dtc-tmp = $(subst $(comma),_,$(dot-target).dts.tmp)
>>>> 
>>>> # Bzip2
>>>> -- 
>>>> 1.9.1
>>> 
>>> Regards
>>> 
>>> — Pantelis

Regards

— Pantelis