* Re: [PATCH] cmd_dtc: Enable generation of device tree symbols
2021-01-26 7:20 ` Uwe Kleine-König
@ 2021-01-26 8:43 ` Geert Uytterhoeven
2021-01-26 18:03 ` Frank Rowand
2021-01-26 13:42 ` Rob Herring
2021-01-26 18:03 ` Frank Rowand
2 siblings, 1 reply; 8+ messages in thread
From: Geert Uytterhoeven @ 2021-01-26 8:43 UTC (permalink / raw)
To: Uwe Kleine-König
Cc: Masahiro Yamada, Michal Marek, Linux Kbuild mailing list,
Linux Kernel Mailing List, linux-arm-kernel, cyril, Arnd Bergmann,
Maxime Ripard, DTML, Rob Herring
Hi Uwe,
On Tue, Jan 26, 2021 at 8:21 AM Uwe Kleine-König <uwe@kleine-koenig.org> wrote:
> And then I learned with hints from Rob and Geert that symbols are not
> really necessary for overlays, you just cannot use named labels. But
> using
>
> target-path = "/soc/i2c@23473245";
>
> or
>
> target = <&{/soc/i2c@23473245}>;
>
> instead of
>
> target = <&i2c1>;
>
> works fine. (And if you need to add a phandle the &{/path/to/node}
> construct should work, too (but I didn't test).) Using labels is a tad
> nicer, but the problem I wanted to address with my patch now has a known
> different solution.
Please don't use "target" and "target-path". Since the introduction of
sugar syntax support in v4.15[1], you can just use "&label", like in a normal
DTS file. Paths do need the special "&{/path/to/node}" syntax instead
of "/path/to/node", though.
As usual, you can find lots of examples of DT overlays in my repo[2].
[1] commit 4201d057ea91c3d6 ("scripts/dtc: Update to upstream version
v1.4.5-3-gb1a60033c110")
[2] https://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers.git/log/?h=topic/renesas-overlays
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH] cmd_dtc: Enable generation of device tree symbols
2021-01-26 8:43 ` Geert Uytterhoeven
@ 2021-01-26 18:03 ` Frank Rowand
0 siblings, 0 replies; 8+ messages in thread
From: Frank Rowand @ 2021-01-26 18:03 UTC (permalink / raw)
To: Geert Uytterhoeven, Uwe Kleine-König, Frank Rowand
Cc: DTML, Michal Marek, Arnd Bergmann, Linux Kbuild mailing list,
Masahiro Yamada, Linux Kernel Mailing List, Maxime Ripard, cyril,
linux-arm-kernel
+frank
On 1/26/21 2:43 AM, Geert Uytterhoeven wrote:
> Hi Uwe,
>
> On Tue, Jan 26, 2021 at 8:21 AM Uwe Kleine-König <uwe@kleine-koenig.org> wrote:
>> And then I learned with hints from Rob and Geert that symbols are not
>> really necessary for overlays, you just cannot use named labels. But
>> using
>>
>> target-path = "/soc/i2c@23473245";
>>
>> or
>>
>> target = <&{/soc/i2c@23473245}>;
>>
>> instead of
>>
>> target = <&i2c1>;
>>
>> works fine. (And if you need to add a phandle the &{/path/to/node}
>> construct should work, too (but I didn't test).) Using labels is a tad
>> nicer, but the problem I wanted to address with my patch now has a known
>> different solution.
>
> Please don't use "target" and "target-path". Since the introduction of
> sugar syntax support in v4.15[1], you can just use "&label", like in a normal
> DTS file. Paths do need the special "&{/path/to/node}" syntax instead
> of "/path/to/node", though.
>
> As usual, you can find lots of examples of DT overlays in my repo[2].
>
> [1] commit 4201d057ea91c3d6 ("scripts/dtc: Update to upstream version
> v1.4.5-3-gb1a60033c110")
> [2] https://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers.git/log/?h=topic/renesas-overlays
>
> Gr{oetje,eeting}s,
>
> Geert
>
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] cmd_dtc: Enable generation of device tree symbols
2021-01-26 7:20 ` Uwe Kleine-König
2021-01-26 8:43 ` Geert Uytterhoeven
@ 2021-01-26 13:42 ` Rob Herring
2021-01-26 18:03 ` Frank Rowand
2 siblings, 0 replies; 8+ messages in thread
From: Rob Herring @ 2021-01-26 13:42 UTC (permalink / raw)
To: Uwe Kleine-König
Cc: Masahiro Yamada, Michal Marek, Linux Kbuild mailing list,
Linux Kernel Mailing List, linux-arm-kernel, cyril, Arnd Bergmann,
Maxime Ripard, DTML, Geert Uytterhoeven, Frank Rowand
On Tue, Jan 26, 2021 at 1:27 AM Uwe Kleine-König <uwe@kleine-koenig.org> wrote:
>
> Hello Masahiro,
>
> On 1/25/21 10:53 PM, Masahiro Yamada wrote:
> > On Mon, Jan 25, 2021 at 8:07 PM Uwe Kleine-König <uwe@kleine-koenig.org> wrote:
> >>
> >> Adding the -@ switch to dtc results in the binary devicetrees containing
> >> a list of symbolic references and their paths. This is necessary to
> >> apply device tree overlays e.g. on Raspberry Pi as described on
> >> https://www.raspberrypi.org/documentation/configuration/device-tree.md.
> >>
> >> Obviously the downside of this change is an increas of the size of the
> >> generated dtbs, for an arm out-of-tree build (multi_v7_defconfig):
> >>
> >> $ du -s arch/arm/boot/dts*
> >> 101380 arch/arm/boot/dts-pre
> >> 114308 arch/arm/boot/dts-post
> >>
> >> so this is in average an increase of 12.8% in size.
> >>
> >> Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
> >
> >
> > (CCing DT ML.)
>
> makes sense, thanks.
>
> > https://www.spinics.net/lists/linux-kbuild/msg27904.html
> >
> > See Rob's comment:
> >
> > "We've already rejected doing that. Turning on '-@' can grow the dtb
> > size by a significant amount which could be problematic for some
> > boards."
>
> The patch was created after some conversation on irc which continued
> after I sent the patch. I added the participating parties to Cc:.
>
> The (relevant) followups were:
>
> Geert suggested to always generate the symbols and provide a way to
> strip the symbols for installation if and when they are not needed.
>
> Rob said: "I'm less concerned with the size increases, but rather that
> labels go from purely source syntax to an ABI. I'd rather see some
> decision as to which labels are enabled or not."
I've also said move the arm32 dts files to family subdirectories and
enable '-@' per directory. I've posted a script to do the whole thing,
but I think the preference is one-by-one. This is needed anyways if
we're going to start adding overlays which Viresh is working on.
Rob
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] cmd_dtc: Enable generation of device tree symbols
2021-01-26 7:20 ` Uwe Kleine-König
2021-01-26 8:43 ` Geert Uytterhoeven
2021-01-26 13:42 ` Rob Herring
@ 2021-01-26 18:03 ` Frank Rowand
2021-01-26 18:26 ` Frank Rowand
2 siblings, 1 reply; 8+ messages in thread
From: Frank Rowand @ 2021-01-26 18:03 UTC (permalink / raw)
To: Uwe Kleine-König, Masahiro Yamada, Frank Rowand
Cc: DTML, Michal Marek, Arnd Bergmann, Linux Kbuild mailing list,
Linux Kernel Mailing List, Maxime Ripard, cyril,
Geert Uytterhoeven, linux-arm-kernel
+frank
On 1/26/21 1:20 AM, Uwe Kleine-König wrote:
> Hello Masahiro,
>
> On 1/25/21 10:53 PM, Masahiro Yamada wrote:
>> On Mon, Jan 25, 2021 at 8:07 PM Uwe Kleine-König <uwe@kleine-koenig.org> wrote:
>>>
>>> Adding the -@ switch to dtc results in the binary devicetrees containing
>>> a list of symbolic references and their paths. This is necessary to
>>> apply device tree overlays e.g. on Raspberry Pi as described on
>>> https://www.raspberrypi.org/documentation/configuration/device-tree.md.
>>>
>>> Obviously the downside of this change is an increas of the size of the
>>> generated dtbs, for an arm out-of-tree build (multi_v7_defconfig):
>>>
>>> $ du -s arch/arm/boot/dts*
>>> 101380 arch/arm/boot/dts-pre
>>> 114308 arch/arm/boot/dts-post
>>>
>>> so this is in average an increase of 12.8% in size.
>>>
>>> Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
>>
>>
>> (CCing DT ML.)
>
> makes sense, thanks.
>
>> https://www.spinics.net/lists/linux-kbuild/msg27904.html
>>
>> See Rob's comment:
>>
>> "We've already rejected doing that. Turning on '-@' can grow the dtb
>> size by a significant amount which could be problematic for some
>> boards."
>
> The patch was created after some conversation on irc which continued
> after I sent the patch. I added the participating parties to Cc:.
>
> The (relevant) followups were:
>
> Geert suggested to always generate the symbols and provide a way to
> strip the symbols for installation if and when they are not needed.
>
> Rob said: "I'm less concerned with the size increases, but rather that
> labels go from purely source syntax to an ABI. I'd rather see some
> decision as to which labels are enabled or not."
>
> And then I learned with hints from Rob and Geert that symbols are not
> really necessary for overlays, you just cannot use named labels. But
> using
>
> target-path = "/soc/i2c@23473245";
>
> or
>
> target = <&{/soc/i2c@23473245}>;
>
> instead of
>
> target = <&i2c1>;
>
> works fine. (And if you need to add a phandle the &{/path/to/node}
> construct should work, too (but I didn't test).) Using labels is a tad nicer, but the problem I wanted to address with my patch now has a known different solution.
>
> Best regards
> Uwe
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH] cmd_dtc: Enable generation of device tree symbols
2021-01-26 18:03 ` Frank Rowand
@ 2021-01-26 18:26 ` Frank Rowand
0 siblings, 0 replies; 8+ messages in thread
From: Frank Rowand @ 2021-01-26 18:26 UTC (permalink / raw)
To: Uwe Kleine-König, Masahiro Yamada, Frank Rowand
Cc: DTML, Michal Marek, Arnd Bergmann, Linux Kbuild mailing list,
Linux Kernel Mailing List, Maxime Ripard, cyril,
Geert Uytterhoeven, linux-arm-kernel
Hi Uwe,
On 1/26/21 12:03 PM, Frank Rowand wrote:
> +frank
>
> On 1/26/21 1:20 AM, Uwe Kleine-König wrote:
>> Hello Masahiro,
>>
>> On 1/25/21 10:53 PM, Masahiro Yamada wrote:
>>> On Mon, Jan 25, 2021 at 8:07 PM Uwe Kleine-König <uwe@kleine-koenig.org> wrote:
>>>>
>>>> Adding the -@ switch to dtc results in the binary devicetrees containing
>>>> a list of symbolic references and their paths. This is necessary to
>>>> apply device tree overlays e.g. on Raspberry Pi as described on
>>>> https://www.raspberrypi.org/documentation/configuration/device-tree.md.
>>>>
>>>> Obviously the downside of this change is an increas of the size of the
>>>> generated dtbs, for an arm out-of-tree build (multi_v7_defconfig):
>>>>
>>>> $ du -s arch/arm/boot/dts*
>>>> 101380 arch/arm/boot/dts-pre
>>>> 114308 arch/arm/boot/dts-post
>>>>
>>>> so this is in average an increase of 12.8% in size.
>>>>
>>>> Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
>>>
>>>
>>> (CCing DT ML.)
>>
>> makes sense, thanks.
>>
>>> https://www.spinics.net/lists/linux-kbuild/msg27904.html
>>>
>>> See Rob's comment:
>>>
>>> "We've already rejected doing that. Turning on '-@' can grow the dtb
>>> size by a significant amount which could be problematic for some
>>> boards."
>>
>> The patch was created after some conversation on irc which continued
>> after I sent the patch. I added the participating parties to Cc:.
Unfortunately I have not been on irc recently (now rectified). Do you
perchance have a copy of the irc conversation that you can send me?
(No need to edit out unrelated messages, a simple cut and paste from
the start of the conversation to the end is fine.)
-Frank
>>
>> The (relevant) followups were:
>>
>> Geert suggested to always generate the symbols and provide a way to
>> strip the symbols for installation if and when they are not needed.
>>
>> Rob said: "I'm less concerned with the size increases, but rather that
>> labels go from purely source syntax to an ABI. I'd rather see some
>> decision as to which labels are enabled or not."
>>
>> And then I learned with hints from Rob and Geert that symbols are not
>> really necessary for overlays, you just cannot use named labels. But
>> using
>>
>> target-path = "/soc/i2c@23473245";
>>
>> or
>>
>> target = <&{/soc/i2c@23473245}>;
>>
>> instead of
>>
>> target = <&i2c1>;
>>
>> works fine. (And if you need to add a phandle the &{/path/to/node}
>> construct should work, too (but I didn't test).) Using labels is a tad nicer, but the problem I wanted to address with my patch now has a known different solution.
>>
>> Best regards
>> Uwe
>>
>>
>> _______________________________________________
>> linux-arm-kernel mailing list
>> linux-arm-kernel@lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>>
>
^ permalink raw reply [flat|nested] 8+ messages in thread