Op 19-03-2023 om 15:09 schreef Krzysztof Kozlowski:
On 17/03/2023 11:39, Jan Jasper de Kroon wrote:
Op 16-03-2023 om 20:25 schreef Krzysztof Kozlowski:
On 16/03/2023 16:29, Jan Jasper de Kroon wrote:
Add an optional 'goodix-hold-in-reset', to the Goodix touchscreen
device tree binding. When set to true, the touchscreen controller will
be held in reset mode during system suspend, reducing power consumption.
If not present, the property defaults to false.
Signed-off-by: Jan Jasper de Kroon <jajadekroon@xxxxxxxxx>
Don't attach new patchsets to some other threads. It messes with our
tools and reading/reviewing process.
Thank you for bringing this to my attention. I apologize for any
inconvenience caused by attaching the patchset to the wrong threads. As a
new user of LKML, I'm still learning the appropriate protocol for
submitting patches. Going forward, I will ensure to attach patchsets to
the correct threads.
---
Changes from v2 to v3:
- Used imperative mood instead of "This patch adds".
- Dropped "I am submitting this patch to..." as it is redundant.
- Removed the paragraph related to the related patch sent to the
linux-input mailing list as it is not necessary.
- Renamed the hold-in-reset-in-suspend function to
goodix-hold-in-reset to prevent potential naming conflicts with other
functions in the codebase. No functional changes were made.
Changes from v1 to v2:
- Updated subject prefix to match subsystem.
- Added more detailed description of the change.
- Fixed formatting issues in commit message.
.../devicetree/bindings/input/touchscreen/goodix.yaml | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/Documentation/devicetree/bindings/input/touchscreen/goodix.yaml b/Documentation/devicetree/bindings/input/touchscreen/goodix.yaml
index 3d016b87c8df..197f8db9acc2 100644
--- a/Documentation/devicetree/bindings/input/touchscreen/goodix.yaml
+++ b/Documentation/devicetree/bindings/input/touchscreen/goodix.yaml
@@ -56,6 +56,13 @@ properties:
touchscreen-size-y: true
touchscreen-swapped-x-y: true
+ goodix-hold-in-reset:
That's not a vendor prefix... missing coma.
Thank you for pointing out the mistake in the vendor prefix. I appreciate
your feedback and apologize for any inconvenience caused. I wasn't aware
of the correct vendor prefix style, but I've learned from developer Hans
de Goede that it should be "goodix,hold-in-reset." I will make sure to
correct this in my local branch and ensure that it is applied correctly in
the future. Thanks again for bringing this to my attention.
+ description: |
+ When set to true, the touchscreen controller will be held in reset mode
+ during system suspend. This can help reduce power consumption, but may
+ cause the touchscreen to take longer to resume when the system is woken
+ up from suspend.
Anyway, my concerns were not answered, so to be clear:
NAK till you answer them. Do not send new versions without answering
existing concerns and discussion.
Thank you again for reviewing my patchset and providing feedback. I
appreciate your time and effort in ensuring the quality and suitability
of the DeviceTree.
Regarding the concerns you raised about the proposed feature, I would
like to address them directly. You mentioned that the property does not
look suitable for Devicetree because it describes system policies that are
not within the scope of Devicetree. While I understand your point, I
believe this property is appropriate for Devicetree for the following
reasons:
- The property directly relates to the hardware configuration of the
device, specifically the touchscreen controller, and is not a software
policy.
Keeping device in reset state is not hardware configuration but driver
behavior. You did not Cc us on all patches for some reason, so it's
difficult to judge what exactly your driver is doing.
Thank you for your response. I apologize for not including all the
necessary information in my previous messages. Like you are already aware,
the DT patch is only one part of the solution, and the driver part has
been submitted to the linux-input mailing list. Here is the link to the
latest patch submission:
https://lore.kernel.org/all/20230316152159.66922-1-jajadekroon@xxxxxxxxx/
I understand that it may have been difficult to judge what the driver is
doing without the complete context. The original patch consists of two
'out-of-tree' commits, one that attempts to power off the touchscreen device
controller completely, including the regulators:
https://github.com/megous/linux/commit/a38e3e2900c69f5b9961aca8e003c21950453857
and another that reverts disabling the regulators:
https://github.com/megous/linux/commit/cafc7adf456c03eb4564c2ba750a5345b9c6ceed
The reason for this is that different peripherals are attached to the same
power supply in the case of the PinePhone Original and PinePhone Pro.
I hope this clarifies part of the situation. If you have any further
questions or concerns, please do not hesitate to let me know.
- The property is required for proper system operation and is not optional
in specific device use cases. To be more specific in the case of the
PinePhone Original and Pro. The original commit message of the driver
implementation in driver/input/touchscreen contained the following:
"It consumes quite a bit of power (~40mW) during system sleep, and more
when the screen is touched."
Because the phone is usually kept in your pocket, so prone to a lot of
screen touches, this is highly undesired behavior for the touchscreen in
this case. This in my opinion makes it a mandatory property in this
situation.
Why then the touchscree should not be kept in reset for other devices?
IOW, this should be always used. If you now say "I prefer to keep or not
keep it in reset for my device" - it's a policy.
Thank you for your question. While it's true that keeping the touchscreen
in reset state during system sleep can reduce power consumption for other
devices, the decision to use this property should be based on the specific
use case and hardware configuration of each device. In the case of the
PinePhone Original and Pro, the touchscreen's power consumption during
system sleep is significant, and the device is often kept in a pocket, so
accidental screen touches can occur frequently, leading to further power
drain. As such, keeping the touchscreen in reset state is necessary for
proper system operation in these specific devices. However, for other
devices with different hardware configurations and use cases, the decision
to use this property should be based on a thorough assessment of the power
consumption and potential impact on system behavior.
- The property is not a user-facing configuration option and is not meant
to be changed by the end-user.
Does not matter.
- The property, although in separate device specific kernel, and still
called 'poweroff-in-suspend' is already in use on specific devices,
including the PinePhone Original and PinePhone Pro.
I could not find such property in the kernel.
I apologize for the confusion, but the current mainline kernel doesn't
include this property. As I stated to support the PinePhone Original and
PinePhone Pro, the community makes use of a forked mainline kernel, with
a lot of out-of-tree patches/commits, mainly maintained by developer
Ondrej Jirman. For the PinePhone Original, the DeviceTree configuration
in the PinePhone DTS gets set in the following commit:
https://github.com/megous/linux/commit/74fc0a5f0527afdccb67ce3be690f0ae18c8eca6
For the PinePhone Pro it is set in the following commit, at line 466:
https://github.com/megous/linux/commit/471c5f33ba74c3d498ccc1eb69c098623b193926#
The property here is still called "poweroff-in-suspend".
However, I understand your concern that Devicetree should not be used for
policies. To address this concern, I would like to propose the following
changes to the property description:
1. Remove the sentence about reducing power consumption, as this could be
considered a policy.
2. Emphasize that the property is a required hardware configuration and
not an optional feature on certain devices.
3. Recommend that any changes to the property value should only be made by
experienced system administrators and not end-users.
Please answer - why this should not be enabled always.
One reason why the Touchscreen Controller should not be kept in reset
always is that some devices may have a use case where the touchscreen
needs to remain active even during system sleep, and keeping it in reset
would cause issues with that case. However, in the case of the
battery-powered PinePhone Original and Pro, keeping the touchscreen
controller in reset during system sleep is required for proper system
operation. Having the device in your pocket makes unintentional screen
touches almost unavoidable, and this property enabled is necessary for
these devices. In the case of the PinePhone Original and Pro, enabling
this feature we do consider its impact on battery life or in other words
power consumption.
But bottomlined, enabling this feature should be evaluated on a
case-by-case basis, taking into consideration the specific device use case
and hardware configurations. Thank you for your feedback.
Best regards,
Krzysztof
