This patchset is an attempt to resolve 'make dtbs_check' warning for
arch timer.
Patch 1 is done in preparation for following patches which defines
compatibles order in more clear way.
Patch 2 documents arm,cortex-a7-timer entry in bindings similar to an
existing entry arm,cortex-a15-timer.
Patch 3 adds above 2 properties in of_match list to bring them in
use.
Please note, this patchset is based on
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git, master
Kuldeep Singh (3):
dt-bindings: timer: Rearrange compatible entries of arch timer
dt-bindings: timer: Document arm,cortex-a7-timer for arch timer
clocksource: arch_timer: Add arm,cortex-a7/15-timer in of_match list
.../devicetree/bindings/timer/arm,arch_timer.yaml | 13 +++++--------
drivers/clocksource/arm_arch_timer.c | 2 ++
2 files changed, 7 insertions(+), 8 deletions(-)
--
2.25.1
On 2022-03-16 09:54, Kuldeep Singh wrote:
> This patchset is an attempt to resolve 'make dtbs_check' warning for
> arch timer.
>
> Patch 1 is done in preparation for following patches which defines
> compatibles order in more clear way.
> Patch 2 documents arm,cortex-a7-timer entry in bindings similar to an
> existing entry arm,cortex-a15-timer.
> Patch 3 adds above 2 properties in of_match list to bring them in
> use.
>
> Please note, this patchset is based on
> git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git,
> master
>
> Kuldeep Singh (3):
> dt-bindings: timer: Rearrange compatible entries of arch timer
> dt-bindings: timer: Document arm,cortex-a7-timer for arch timer
> clocksource: arch_timer: Add arm,cortex-a7/15-timer in of_match list
>
> .../devicetree/bindings/timer/arm,arch_timer.yaml | 13 +++++--------
> drivers/clocksource/arm_arch_timer.c | 2 ++
> 2 files changed, 7 insertions(+), 8 deletions(-)
Please use my @kernel.org address exclusively. My @arm.com
address stopped working over two years ago, and the MAINTAINERS
file shows the right addresses.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
Few platforms such as Renesas RZ/N1D, Calxeda, Alpine etc. are using
arm,cortex-a15-timer and arm,cortex-a7-timer entries in conjugation with
arm,armv7-timer which are not currently defined in driver file. Add
these entries in arch_timer_of_match list to bring them in use.
Signed-off-by: Kuldeep Singh <[email protected]>
---
drivers/clocksource/arm_arch_timer.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 1ecd52f903b8..805e60c09916 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -1266,6 +1266,8 @@ static int __init arch_timer_mem_register(void __iomem *base, unsigned int irq)
static const struct of_device_id arch_timer_of_match[] __initconst = {
{ .compatible = "arm,armv7-timer", },
{ .compatible = "arm,armv8-timer", },
+ { .compatible = "arm,cortex-a7-timer", },
+ { .compatible = "arm,cortex-a15-timer", },
{},
};
--
2.25.1
Renesas RZ/N1D platform uses compatible "arm,cortex-a7-timer" in
conjugation with "arm,armv7-timer". Since, initial entry is not
documented, it start raising dtbs_check warnings.
['arm,cortex-a7-timer', 'arm,armv7-timer'] is too long
'arm,cortex-a7-timer' is not one of ['arm,armv7-timer', 'arm,armv8-timer']
'arm,cortex-a7-timer' is not one of ['arm,cortex-a15-timer']
In general, removing an existing entry is mostly devastating considering
backward compatibility. Therefore, document it.
Signed-off-by: Kuldeep Singh <[email protected]>
---
Documentation/devicetree/bindings/timer/arm,arch_timer.yaml | 1 +
1 file changed, 1 insertion(+)
diff --git a/Documentation/devicetree/bindings/timer/arm,arch_timer.yaml b/Documentation/devicetree/bindings/timer/arm,arch_timer.yaml
index ba2910f0a7b2..ea390e5df71d 100644
--- a/Documentation/devicetree/bindings/timer/arm,arch_timer.yaml
+++ b/Documentation/devicetree/bindings/timer/arm,arch_timer.yaml
@@ -26,6 +26,7 @@ properties:
- arm,armv8-timer
- items:
- enum:
+ - arm,cortex-a7-timer
- arm,cortex-a15-timer
- const: arm,armv7-timer
--
2.25.1
On 17/03/2022 07:59, Kuldeep Singh wrote:
> On Wed, Mar 16, 2022 at 06:43:15PM +0000, Marc Zyngier wrote:
>> On Wed, 16 Mar 2022 17:41:08 +0000,
>> Kuldeep Singh <[email protected]> wrote:
>>>
>>> On Wed, Mar 16, 2022 at 05:30:26PM +0100, Krzysztof Kozlowski wrote:
>>>> On 16/03/2022 10:54, Kuldeep Singh wrote:
>>>>> Few platforms such as Renesas RZ/N1D, Calxeda, Alpine etc. are using
>>>>> arm,cortex-a15-timer and arm,cortex-a7-timer entries in conjugation with
>>>>> arm,armv7-timer which are not currently defined in driver file. Add
>>>>> these entries in arch_timer_of_match list to bring them in use.
>>>>>
>>>>
>>>> This looks wrong (also Marc pointed this out) and rationale is not
>>>> sufficient. Why do you need these compatibles in the driver?
>>>
>>> Hi Krzysztof and Marc,
>>>
>>> I find myself in trouble whenever dealing with compatible entries and
>>> had 2 options when I stumble this issue.
>>> 1. Remove unused compatible
>>
>> That'd be silly.
>>
>>> 2. Add required compatible to binding and driver
>>
>> To the binding, yes. But to the driver?
>>
>>> My past experience and advise from other developer says not to remove an
>>> existing compatible. And also I found "arm,cortex-a15-timer" in binding
>>> which was again not documented and was present in DT. This prompted me
>>> to go for second option and make necessary additions in binding and
>>> driver following current entries.
>>
>> The "arm,cortex-a15-timer" compatible is documentation, and only
>> that. If, one day, we find a bug in this implementation, we could work
>> around it in the driver thanks to the separate compatible (although in
>> this case, we'd have much better way of doing that).
>>
>>> As per your perspective, current configuration isn't apt which means
>>> "arm,cortex-a15-timer" is a stub and is wrongly present in binding.
>>
>> That's not what I said. This compatible string is perfectly fine, and
>> accurately describe the HW. The driver doesn't need to know about the
>> fine details of the implementation, and is perfectly happy with the
>> current state of things.
>>
>> Think of it as an instance of a class. The driver doesn't need to know
>> the instance, only that it is a certain class.
>>
>
> Thanks Marc for sharing knowledge. This was indeed helpful.
> To sum up from what I understood, bindings and DTs should always be in
> sync and driver file may not need to define all compatible entries as
> long as purpose is served.
>
> This means no driver change will be required to address
> "arm,cortex-a7-timer". To which I have a question to Krzysztof.
>
> Hi Krzysztof,
>
> As per your comments on 2/3 patch, that it's DT which is not aligned
> with binding w.r.t arm,cortex-a7-timer.
>
> What makes "arm,cortex-a7-timer" an invalid entry from binding
> perspective when we have a similar entry "arm,cortex-a15-timer" already
> present?
>
> I think we should share some common grounds here and keep both of them
> in bindings or remove them altogether. I prefer first option, What's
> your say?
In this case the compatible should be added, just please explain it in
the message. Your previous commit msg was saying about disastrous
backward compatibility issue which so far does not exist here. It's
simply more detailed compatible.
There were few other cases where more detailed compatible was actually
unwanted, so that's why each case should be analyzed.
Best regards,
Krzysztof