Thread (14 messages) 14 messages, 4 authors, 2016-06-23

[PATCH 1/3] Documentation: dtb: xgene: Add hwmon dts binding documentation

From: Hoan Tran <hidden>
Date: 2016-06-23 16:42:08
Also in: linux-devicetree, linux-hwmon, lkml

On Tue, Jun 7, 2016 at 11:05 AM, Hoan Tran [off-list ref] wrote:
Hi Jassi,

Thanks for your reply !

On Tue, Jun 7, 2016 at 10:20 AM, Jassi Brar [off-list ref] wrote:
quoted
On Tue, May 24, 2016 at 6:31 AM, Hoan Tran [off-list ref] wrote:
quoted
Hi Rob,

Thanks for your review !

On Mon, May 23, 2016 at 1:30 PM, Rob Herring [off-list ref] wrote:
quoted
On Mon, May 16, 2016 at 09:17:25AM -0700, Hoan Tran wrote:
quoted
This patch adds the APM X-Gene hwmon device tree node documentation.

Signed-off-by: Hoan Tran <redacted>
---
 .../devicetree/bindings/hwmon/apm-xgene-hwmon.txt          | 14 ++++++++++++++
 1 file changed, 14 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwmon/apm-xgene-hwmon.txt
diff --git a/Documentation/devicetree/bindings/hwmon/apm-xgene-hwmon.txt b/Documentation/devicetree/bindings/hwmon/apm-xgene-hwmon.txt
new file mode 100644
index 0000000..49a482e
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwmon/apm-xgene-hwmon.txt
@@ -0,0 +1,14 @@
+APM X-Gene hwmon driver
+
+Hwmon driver accesses sensors over the "SLIMpro" mailbox.
DT bindings describe h/w, not driver data.
How about this description: "APM X-Gene SOC sensors are accessed over
the "SLIMpro" mailbox" ?
quoted
I'm not sure this belongs in
DT and perhaps the devices for the mailbox should be created by the
mailbox driver.
I don't think the current mailbox supports it.
quoted
quoted
+
+Required properties :
+ - compatible : should be "apm,xgene-slimpro-hwmon"
+ - mboxes : use the label reference for the mailbox as the first parameter.
+         The second parameter is the channel number.
When do you expect this to be different mailbox numbers?
No, this number is not changed. This "mboxes" property is used and
required by mailbox.c when hwmon driver requests a mailbox channel
I think that's inaccurate.

The h/w and the firmware combined is the "platform" from Linux POV.
Channels are physical resources provided by a mailbox controller.
Currently the firmware listens on Channel-7 but some future revision
might switch to, say, Channel-9.  Or say the same firmware on next
revision of h/w may have to switch to Channel-3 because it has only 4
channels. So I see the mailbox channel number as a hardware property
just like an IRQ (which very often change with SoC iterations).
Agree about that. I suppose this number is not changed. But as you
said, the mailbox channel number can be changed based on SoC or
Firmware. It would be better if this channel number is specified
inside a DT node.

Hi Rob, do you have any comments ?

Thanks
Hoan
quoted
Cheers.
Hi Rob,

Do you have any comments on Jassi's reply ?
If not, I'll send another version which included the binding document
and DT node.

Thanks
Hoan
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