Re: [PATCH v11 1/5] dt-bindings: Introduce QCOM Sleep stats bindings
From: Maulik Shah
Date: Wed Oct 13 2021 - 01:57:51 EST
Hi Stephan,
On 10/8/2021 4:29 PM, Stephan Gerhold wrote:
On Fri, Oct 08, 2021 at 02:20:24PM +0530, Maulik Shah wrote:
On 10/8/2021 1:20 AM, Stephan Gerhold wrote:
On Thu, Oct 07, 2021 at 03:27:25PM +0530, Maulik Shah wrote:
From: Mahesh Sivasubramanian <msivasub@xxxxxxxxxxxxxx>
Add device binding documentation for Qualcomm Technologies, Inc. (QTI)
Sleep stats driver. The driver is used for displaying Sleep statistic maintained
by Always On Processor or Resource Power Manager.
Cc: devicetree@xxxxxxxxxxxxxxx
Signed-off-by: Mahesh Sivasubramanian <msivasub@xxxxxxxxxxxxxx>
Signed-off-by: Lina Iyer <ilina@xxxxxxxxxxxxxx>
Signed-off-by: Maulik Shah <mkshah@xxxxxxxxxxxxxx>
Reviewed-by: Rob Herring <robh@xxxxxxxxxx>
Reviewed-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
Reviewed-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
---
.../bindings/soc/qcom/qcom-sleep-stats.yaml | 47 ++++++++++++++++++++++
1 file changed, 47 insertions(+)
create mode 100644 Documentation/devicetree/bindings/soc/qcom/qcom-sleep-stats.yaml
diff --git a/Documentation/devicetree/bindings/soc/qcom/qcom-sleep-stats.yaml b/Documentation/devicetree/bindings/soc/qcom/qcom-sleep-stats.yaml
new file mode 100644
index 0000000..5213daf
--- /dev/null
+++ b/Documentation/devicetree/bindings/soc/qcom/qcom-sleep-stats.yaml
@@ -0,0 +1,47 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/soc/qcom/qcom-sleep-stats.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Qualcomm Technologies, Inc. (QTI) Sleep stats bindings
+
+maintainers:
+ - Maulik Shah <mkshah@xxxxxxxxxxxxxx>
+
+description:
+ Always On Processor/Resource Power Manager maintains statistics of the SoC
+ sleep modes involving powering down of the rails and oscillator clock.
+
+ Statistics includes SoC sleep mode type, number of times low power mode were
+ entered, time of last entry, time of last exit and accumulated sleep duration.
+
+properties:
+ compatible:
+ enum:
+ - qcom,rpmh-sleep-stats
+ - qcom,rpm-sleep-stats
+
+ reg:
+ maxItems: 1
+
+required:
+ - compatible
+ - reg
+
+additionalProperties: false
+
+examples:
+ # Example of rpmh sleep stats
+ - |
+ sram@c3f0000 {
+ compatible = "qcom,rpmh-sleep-stats";
+ reg = <0x0c3f0000 0x400>;
+ };
+ # Example of rpm sleep stats
+ - |
+ sram@4690000 {
+ compatible = "qcom,rpm-sleep-stats";
+ reg = <0x04690000 0x400>;
+ };
Does this region really only contain "rpm-*sleep*-stats"? AFAICT this is
really a more generic memory region where various offsets are read from.
Right the area contains all kind of sleep stats/logs.
These are all the offsets in msm8998-pm.dtsi downstream [1]:
...9000c: rpm-rail-stats offset
...90014: rpm-sleep-stats offset (RPM_DYNAMIC_ADDR in your driver)
...90018: rpm-log offset
...9001c: "RPM FREE HEAP SPACE"
How would you set up any of the other drivers if the entire region
is declared as "rpm-sleep-stats"?
We don't need to setup other drivers.
The idea is to have single stats driver (qcom_sleep_stats) that can be
enahanced to to read other stats also on both RPM/ PRMH targets.
Today this driver reads only sleep stats from offset 0x90014.
if in future say, we want to read rpm-rail-stats from offset 0x9000c then it
can be added in the existing driver.
In the rpm data, add one more entry to indicate reading rpm-rail-stats,
something like below and add new compatible flag for the target, may be
"qcom,rpm-sleep-stats-legacy" and should work like,
#define RPM_RAIL_STATS_ADDR 0xc
static const struct stats_config rpm_data = {
.stats_offset = 0,
.num_records = 2,
.appended_stats_avail = true,
.dynamic_offset = true,
.rpm_rail_stats = true,
};
and check in driver probe like
if (config->rpm_rail_stats) {
//create rpm rail stats related files.
}
Similarly for other rpm-logs / any other stats can be added in same driver.
Hope this clarifies.
Having the same driver for all this sounds good, thanks for clarifying!
Perhaps this region should have a more generic name that represents what
it actually is and not only one of the information it contains, similar
to "qcom,rpm-msg-ram"?
sram looks good to me. Actually on RPM targets its RPM data ram and RPMH
targets its msgram. To keep the name common sram is used here.
The node name (sram@...) is fine. I was actually referring to the
"compatible". Given what you have written above there is more in that
region than just "qcom,rpm-*sleep*-stats". There are also logs and other
stats there. Perhaps "qcom,rpm(h)-stats" (without -sleep-) would already
be more clear.
ok updated in v12 to name it qcom,rpm(h)-stats. similarly driver name
also updated from qcom_sleep_stats to qcom_stats.
Or, my other suggestion was to not make any assumption about particular
contents of the data RAM in the device tree. The compatible could also
be called simply "qcom,rpm-data-ram" (just like "qcom,rpm-msg-ram") and
the assumption what it contains (e.g. sleep stats) could be made in your
existing driver.
This is probably a matter of preference at the end and won't make a big
difference but I just wanted to mention it.
For example, to make your driver work on MSM8916 I had to declare a much
larger memory region (e.g. 0x10000 vs 0x400):
sram@290000 {
compatible = "qcom,rpm-sleep-stats";
reg = <0x00290000 0x10000>;
};
the driver can not be as is enabled for MSM8916. Actually on MSM8916
(even though its RPM target) it uses fixed offset 0xdba0 from the base
address in the devicetree.
This is because RPM_DYNAMIC_ADDR contains the offset 0xdba0 instead of
e.g. 0x020c on newer SoCs and the memory region must be large enough to
cover the offset.
On all other RPM targets followed by MSM8916 the address for soc sleep
stats is present at offset 0x14 (RPM_DYNAMIC_ADDR ) from the base
address but not on MSM8916. so MSM8916 is a special case to enable for
for RPM stats
To enable this for MSM8916, dynamic_offset need to be false and
stats_offset need to be given directly as 0xdba0, something similar as
RPMH targets.
static const struct stats_config rpm_legacy_data = {
.stats_offset = 0xdba0,
.num_records = 2,
.appended_stats_avail = true,
.dynamic_offset = false,
.subsystem_stats_in_smem = false,
};
{ .compatible = "qcom,rpm-legacy-stats", .data = &rpm_legacy_data },
and then add
sram@290000 {
compatible = "qcom,rpm-legacy-stats";
reg = <0x00290000 0x10000>;
};
which should work fine.
I donot have MSM8916 to validate this but when this driver boots up it
should create "vlow" and "vmin" files at /sys/kernel/debug/qcom_sleep_stats/
if that is done, it means you are reading stats from correct address
since the file name is read from the memory itself.
Thanks,
Maulik
It just feels a bit weird for me to describe such a large region as only
containing "qcom,rpm-*sleep*-stats". "qcom,rpm-data-ram" might better
describe it what it really is and then your driver can decide what to do
with it.
But, as I said, this is just naming which is always subjective. :)
Thanks!
Stephan
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