Documentation: dt: Explicitly mark Samsung Exynos SoC bindings as unstable

Message ID 1481897676-13578-1-git-send-email-m.szyprowski@samsung.com
State New
Headers show

Commit Message

Marek Szyprowski Dec. 16, 2016, 2:14 p.m.
Samsung Exynos SoCs and boards related bindings evolved since the initial
introduction, but initially the bindings were minimal and a bit incomplete
(they never described all the hardware modules available in the SoCs).
Since then some significant (not fully compatible) changes have been
already committed a few times (like gpio replaced by pinctrl, display ddc,
mfc reserved memory, some core clocks added to various hardware modules,
added more required nodes).

On the other side there are no boards which have device tree embedded in
the bootloader. Device tree blob is always compiled from the kernel tree
and updated together with the kernel image.

Thus to avoid further adding a bunch of workarounds for old/missing
bindings and allow to make cleanup of the existing code and device tree
files, lets mark Samsung Exynos SoC platform bindings as unstable. This
means that bindings can may change at any time and users should use the
dtb file compiled from the same kernel source tree as the kernel image.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

---
 Documentation/devicetree/bindings/arm/samsung/exynos.txt | 12 ++++++++++++
 1 file changed, 12 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/arm/samsung/exynos.txt

-- 
1.9.1

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Comments

Javier Martinez Canillas Dec. 16, 2016, 2:18 p.m. | #1
Hello Marek,

On 12/16/2016 11:14 AM, Marek Szyprowski wrote:
> Samsung Exynos SoCs and boards related bindings evolved since the initial

> introduction, but initially the bindings were minimal and a bit incomplete

> (they never described all the hardware modules available in the SoCs).

> Since then some significant (not fully compatible) changes have been

> already committed a few times (like gpio replaced by pinctrl, display ddc,

> mfc reserved memory, some core clocks added to various hardware modules,

> added more required nodes).

> 

> On the other side there are no boards which have device tree embedded in

> the bootloader. Device tree blob is always compiled from the kernel tree

> and updated together with the kernel image.

> 

> Thus to avoid further adding a bunch of workarounds for old/missing

> bindings and allow to make cleanup of the existing code and device tree

> files, lets mark Samsung Exynos SoC platform bindings as unstable. This

> means that bindings can may change at any time and users should use the

> dtb file compiled from the same kernel source tree as the kernel image.

> 

> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

> ---


I completely agree with you on this.

Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>

-- 
Javier Martinez Canillas
Open Source Group
Samsung Research America
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Bartlomiej Zolnierkiewicz Dec. 16, 2016, 2:27 p.m. | #2
Hi,

On Friday, December 16, 2016 03:14:36 PM Marek Szyprowski wrote:
> Samsung Exynos SoCs and boards related bindings evolved since the initial

> introduction, but initially the bindings were minimal and a bit incomplete

> (they never described all the hardware modules available in the SoCs).

> Since then some significant (not fully compatible) changes have been

> already committed a few times (like gpio replaced by pinctrl, display ddc,

> mfc reserved memory, some core clocks added to various hardware modules,

> added more required nodes).

> 

> On the other side there are no boards which have device tree embedded in

> the bootloader. Device tree blob is always compiled from the kernel tree

> and updated together with the kernel image.

> 

> Thus to avoid further adding a bunch of workarounds for old/missing

> bindings and allow to make cleanup of the existing code and device tree

> files, lets mark Samsung Exynos SoC platform bindings as unstable. This

> means that bindings can may change at any time and users should use the

> dtb file compiled from the same kernel source tree as the kernel image.

> 

> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>


This change is long overdue..

Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>


> ---

>  Documentation/devicetree/bindings/arm/samsung/exynos.txt | 12 ++++++++++++

>  1 file changed, 12 insertions(+)

>  create mode 100644 Documentation/devicetree/bindings/arm/samsung/exynos.txt

> 

> diff --git a/Documentation/devicetree/bindings/arm/samsung/exynos.txt b/Documentation/devicetree/bindings/arm/samsung/exynos.txt

> new file mode 100644

> index 000000000000..0c606f4c6e85

> --- /dev/null

> +++ b/Documentation/devicetree/bindings/arm/samsung/exynos.txt

> @@ -0,0 +1,12 @@

> +Samsung Exynos SoC Family Device Tree Bindings

> +---------------------------------------------------------------

> +

> +Work in progress statement:

> +

> +Device tree files and bindings applying to Samsung Exynos SoCs and boards are

> +considered "unstable". Any Samsung Exynos device tree binding may change at any

> +time. Be sure to use a device tree binary and a kernel image generated from the

> +same source tree.

> +

> +Please refer to Documentation/devicetree/bindings/ABI.txt for a definition of a

> +stable binding/ABI.


Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics

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pankaj.dubey Dec. 17, 2016, 3:31 a.m. | #3
Hi Marek,

On 16 December 2016 at 19:44, Marek Szyprowski <m.szyprowski@samsung.com> wrote:
> Samsung Exynos SoCs and boards related bindings evolved since the initial

> introduction, but initially the bindings were minimal and a bit incomplete

> (they never described all the hardware modules available in the SoCs).

> Since then some significant (not fully compatible) changes have been

> already committed a few times (like gpio replaced by pinctrl, display ddc,

> mfc reserved memory, some core clocks added to various hardware modules,

> added more required nodes).

>

> On the other side there are no boards which have device tree embedded in

> the bootloader. Device tree blob is always compiled from the kernel tree

> and updated together with the kernel image.

>

> Thus to avoid further adding a bunch of workarounds for old/missing

> bindings and allow to make cleanup of the existing code and device tree

> files, lets mark Samsung Exynos SoC platform bindings as unstable. This

> means that bindings can may change at any time and users should use the

> dtb file compiled from the same kernel source tree as the kernel image.

>

> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

> ---


I agree with you. This is very much required. It's not only about new
bindings, we are facing problems in adopting existing bindings as well
(e.g scu), to make exynos support completely DT based and simplify our
code base.

I expect and foresee requirements of many more such changes in very near future.

Reviewed-by: Pankaj Dubey <pankaj.dubey@samsung.com>


Thanks,
Pankaj Dubey
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Krzysztof Kozlowski Dec. 17, 2016, 7:37 p.m. | #4
On Fri, Dec 16, 2016 at 03:14:36PM +0100, Marek Szyprowski wrote:
> Samsung Exynos SoCs and boards related bindings evolved since the initial

> introduction, but initially the bindings were minimal and a bit incomplete

> (they never described all the hardware modules available in the SoCs).

> Since then some significant (not fully compatible) changes have been

> already committed a few times (like gpio replaced by pinctrl, display ddc,

> mfc reserved memory, some core clocks added to various hardware modules,

> added more required nodes).

> 

> On the other side there are no boards which have device tree embedded in

> the bootloader. Device tree blob is always compiled from the kernel tree

> and updated together with the kernel image.

> 

> Thus to avoid further adding a bunch of workarounds for old/missing

> bindings and allow to make cleanup of the existing code and device tree

> files, lets mark Samsung Exynos SoC platform bindings as unstable. This

> means that bindings can may change at any time and users should use the

> dtb file compiled from the same kernel source tree as the kernel image.


I agree but please re-send it after merge window. This is not the best
time to start discussions about it.

Best regards,
Krzysztof


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Rob Herring Dec. 21, 2016, 3:36 a.m. | #5
On Fri, Dec 16, 2016 at 03:14:36PM +0100, Marek Szyprowski wrote:
> Samsung Exynos SoCs and boards related bindings evolved since the initial

> introduction, but initially the bindings were minimal and a bit incomplete

> (they never described all the hardware modules available in the SoCs).

> Since then some significant (not fully compatible) changes have been

> already committed a few times (like gpio replaced by pinctrl, display ddc,

> mfc reserved memory, some core clocks added to various hardware modules,

> added more required nodes).

> 

> On the other side there are no boards which have device tree embedded in

> the bootloader. Device tree blob is always compiled from the kernel tree

> and updated together with the kernel image.

> 

> Thus to avoid further adding a bunch of workarounds for old/missing

> bindings and allow to make cleanup of the existing code and device tree

> files, lets mark Samsung Exynos SoC platform bindings as unstable. This

> means that bindings can may change at any time and users should use the

> dtb file compiled from the same kernel source tree as the kernel image.


I'd like this to be more explicit about which bindings in particular are 
not considered stable (or which ones are). "exynos" covers lots of 
things.

I'll still complain if commit messages don't say explicitly that the 
commit breaks compatibility and why that is okay.

Rob
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Patch hide | download patch | download mbox

diff --git a/Documentation/devicetree/bindings/arm/samsung/exynos.txt b/Documentation/devicetree/bindings/arm/samsung/exynos.txt
new file mode 100644
index 000000000000..0c606f4c6e85
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/samsung/exynos.txt
@@ -0,0 +1,12 @@ 
+Samsung Exynos SoC Family Device Tree Bindings
+---------------------------------------------------------------
+
+Work in progress statement:
+
+Device tree files and bindings applying to Samsung Exynos SoCs and boards are
+considered "unstable". Any Samsung Exynos device tree binding may change at any
+time. Be sure to use a device tree binary and a kernel image generated from the
+same source tree.
+
+Please refer to Documentation/devicetree/bindings/ABI.txt for a definition of a
+stable binding/ABI.