Re: [PATCH 6/6] remoteproc: qcom: Add notification types to SSR
From: Siddharth Gupta
Date: Wed Apr 01 2020 - 21:02:40 EST
On 3/9/2020 10:34 AM, Mathieu Poirier wrote:
On Tue, 3 Mar 2020 at 16:30, <rishabhb@xxxxxxxxxxxxxx> wrote:
On 2020-03-03 10:05, Mathieu Poirier wrote:
On Mon, 2 Mar 2020 at 13:54, <rishabhb@xxxxxxxxxxxxxx> wrote:
On 2020-02-28 10:38, Mathieu Poirier wrote:
On Thu, Feb 27, 2020 at 04:00:21PM -0800, rishabhb@xxxxxxxxxxxxxx
wrote:
On 2020-02-27 13:59, Mathieu Poirier wrote:
On Wed, Feb 19, 2020 at 06:57:45PM -0800, Siddharth Gupta wrote:
The SSR subdevice only adds callback for the unprepare event. Add
callbacks
for unprepare, start and prepare events. The client driver for a
particular
remoteproc might be interested in knowing the status of the remoteproc
while undergoing SSR, not just when the remoteproc has finished
shutting
down.
Signed-off-by: Siddharth Gupta <sidgup@xxxxxxxxxxxxxx>
---
drivers/remoteproc/qcom_common.c | 39
+++++++++++++++++++++++++++++++++++----
include/linux/remoteproc.h | 15 +++++++++++++++
2 files changed, 50 insertions(+), 4 deletions(-)
diff --git a/drivers/remoteproc/qcom_common.c
b/drivers/remoteproc/qcom_common.c
index 6714f27..6f04a5b 100644
--- a/drivers/remoteproc/qcom_common.c
+++ b/drivers/remoteproc/qcom_common.c
@@ -183,9 +183,9 @@ EXPORT_SYMBOL_GPL(qcom_remove_smd_subdev);
*
* Returns pointer to srcu notifier head on success, ERR_PTR on
failure.
*
- * This registers the @notify function as handler for restart
notifications. As
- * remote processors are stopped this function will be called, with
the rproc
- * pointer passed as a parameter.
+ * This registers the @notify function as handler for
powerup/shutdown
+ * notifications. This function will be invoked inside the
callbacks registered
+ * for the ssr subdevice, with the rproc pointer passed as a
parameter.
*/
void *qcom_register_ssr_notifier(struct rproc *rproc, struct
notifier_block *nb)
{
@@ -227,11 +227,39 @@ int qcom_unregister_ssr_notifier(void *notify,
struct notifier_block *nb)
}
EXPORT_SYMBOL_GPL(qcom_unregister_ssr_notifier);
+static int ssr_notify_prepare(struct rproc_subdev *subdev)
+{
+ struct qcom_rproc_ssr *ssr = to_ssr_subdev(subdev);
+
+ srcu_notifier_call_chain(ssr->rproc_notif_list,
+ RPROC_BEFORE_POWERUP, (void *)ssr->name);
+ return 0;
+}
+
+static int ssr_notify_start(struct rproc_subdev *subdev)
+{
+ struct qcom_rproc_ssr *ssr = to_ssr_subdev(subdev);
+
+ srcu_notifier_call_chain(ssr->rproc_notif_list,
+ RPROC_AFTER_POWERUP, (void *)ssr->name);
+ return 0;
+}
+
+static void ssr_notify_stop(struct rproc_subdev *subdev, bool
crashed)
+{
+ struct qcom_rproc_ssr *ssr = to_ssr_subdev(subdev);
+
+ srcu_notifier_call_chain(ssr->rproc_notif_list,
+ RPROC_BEFORE_SHUTDOWN, (void *)ssr->name);
+}
+
+
static void ssr_notify_unprepare(struct rproc_subdev *subdev)
{
struct qcom_rproc_ssr *ssr = to_ssr_subdev(subdev);
- srcu_notifier_call_chain(ssr->rproc_notif_list, 0, (void
*)ssr->name);
+ srcu_notifier_call_chain(ssr->rproc_notif_list,
+ RPROC_AFTER_SHUTDOWN, (void *)ssr->name);
}
/**
@@ -248,6 +276,9 @@ void qcom_add_ssr_subdev(struct rproc *rproc,
struct qcom_rproc_ssr *ssr,
{
ssr->name = ssr_name;
ssr->subdev.name = kstrdup("ssr_notifs", GFP_KERNEL);
+ ssr->subdev.prepare = ssr_notify_prepare;
+ ssr->subdev.start = ssr_notify_start;
+ ssr->subdev.stop = ssr_notify_stop;
Now that I have a better understanding of what this patchset is doing, I
realise
my comments in patch 04 won't work. To differentiate the subdevs of an
rproc I
suggest to wrap them in a generic structure with a type and an enum.
That way
you can differenciate between subdevices without having to add to the
core.
While creating a new revision of the patchset we tried to implement
this, but a similar issue comes
up. If at a later point we wish to utilize the functionality of some
common subdevice (not the case
right now, but potentially), we might run into a similar problem of
accessing illegal memory using
container_of. I think it might be a better idea to introduce the name in
the subdevice structure over
having a potential security bug. What do you think?
Thanks,
Siddharth
Ok. I can try that.
That being said, I don't understand what patches 5 and 6 are doing...
Registering with the global ssr_notifiers allowed to gracefully shutdown
all the
MCUs in the system when one of them would go down. But now that we are
using
the notifier on a per MCU, I really don't see why each subdev couldn't
implement
the right prepare/start/stop functions.
Am I missing something here?
We only want kernel clients to be notified when the Remoteproc they
are
interested
in changes state. For e.g. audio kernel driver should be notified when
audio
processor goes down but it does not care about any other remoteproc.
If you are suggesting that these kernel clients be added as subdevices
then
we will end up having many subdevices registered to each remoteproc.
So we
implemented a notifier chain per Remoteproc. This keeps the SSR
notifications as
the subdevice per remoteproc, and all interested clients can register
to it.
It seems like I am missing information... Your are referring to
"kernel
clients" and as such I must assume some drivers that are not part of
the
remoteproc/rpmsg subsystems are calling qcom_register_ssr_notifier().
I must
Yes these are not part of remoteproc framework and they will register
for notifications.
also assume these drivers (or that functionality) are not yet upsream
because
all I can see calling qcom_register_ssr_notifier() is
qcom_glink_ssr_probe().
Correct.These are not upstreamed.
Ok, things are starting to make sense.
Speaking of which, what is the role of the qcom_glink_ssr_driver? Is
the glink
device that driver is handling the same as the glink device registed in
adsp_probe() and q6v5_probe()?
glink ssr driver will send out notifications to remoteprocs that have
opened the
"glink_ssr" channel that some subsystem has gone down or booted up.
This
helps notify
neighboring subsystems about change in state of any other subsystem.
I am still looking for an answer to my second question.
Yes its the subdevice of the glink device that is registered in
adsp_probe.
It uses the "glink_ssr" glink channel.
Since this is confining events to a single MCU, I was mostly worried
about opening the "glink_ssr" channel for nothing but taking a step
back and thinking further on this, there might be other purposes for
the channel than only receiving notifications of other MCUs in the
system going down.
Please spin off a new revision of this set and I will take another look.
Thanks,
Mathieu
ssr->subdev.unprepare = ssr_notify_unprepare;
ssr->rproc_notif_list = kzalloc(sizeof(struct srcu_notifier_head),
GFP_KERNEL);
diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
index e2f60cc..4be4478 100644
--- a/include/linux/remoteproc.h
+++ b/include/linux/remoteproc.h
@@ -449,6 +449,21 @@ struct rproc_dump_segment {
};
/**
+ * enum rproc_notif_type - Different stages of remoteproc
notifications
+ * @RPROC_BEFORE_SHUTDOWN: unprepare stage of remoteproc
+ * @RPROC_AFTER_SHUTDOWN: stop stage of remoteproc
+ * @RPROC_BEFORE_POWERUP: prepare stage of remoteproc
+ * @RPROC_AFTER_POWERUP: start stage of remoteproc
+ */
+enum rproc_notif_type {
+ RPROC_BEFORE_SHUTDOWN,
+ RPROC_AFTER_SHUTDOWN,
+ RPROC_BEFORE_POWERUP,
+ RPROC_AFTER_POWERUP,
+ RPROC_MAX
+};
+
+/**
* struct rproc - represents a physical remote processor device
* @node: list node of this rproc object
* @domain: iommu domain
--
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a Linux Foundation Collaborative Project
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