Re: [PATCH v3 03/14] remoteproc: Add new operation and flags for synchronistation

Bjorn Andersson
2020-05-06T00:22:10Z

On Fri 24 Apr 13:01 PDT 2020, Mathieu Poirier wrote:

> Add a new sync_ops to support use cases where the remoteproc
> core is synchronising with the remote processor. Exactly when to use
> the synchronisation operations is directed by the flags in structure
> rproc_sync_flags.
>

I'm sorry, but no matter how many times I read these patches I have to
translate "synchronising" to "remote controlled", and given the number
of comments clarifying this makes me feel that we could perhaps come up
with a better name?

> Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
> ---
> include/linux/remoteproc.h | 24 ++++++++++++++++++++++++
> 1 file changed, 24 insertions(+)
>
> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> index ac4082f12e8b..ceb3b2bba824 100644
> --- a/include/linux/remoteproc.h
> +++ b/include/linux/remoteproc.h
> @@ -353,6 +353,23 @@ enum rsc_handling_status {
> RSC_IGNORED = 1,
> };
>
> +/**
> + * struct rproc_sync_flags - platform specific flags indicating which
> + * rproc_ops to use at specific times during
> + * the rproc lifecycle.
> + * @on_init: true if synchronising with the remote processor at
> + * initialisation time
> + * @after_stop: true if synchronising with the remote processor after it was
> + * stopped from the cmmand line
> + * @after_crash: true if synchronising with the remote processor after
> + * it has crashed
> + */
> +struct rproc_sync_flags {
> + bool on_init;

This indirectly splits the RPROC_OFFLINE state in an "offline" and
"already-booted" state. Wouldn't it be clearer to represent this with a
new RPROC_ALREADY_BOOTED state?

> + bool after_stop;

What does it mean when this is true? That Linux can shut the remote core
down, but someone else will start it?

> + bool after_crash;

Similarly what is the expected steps to be taken by the core when this
is true? Should rproc_report_crash() simply stop/start the subdevices
and upon one of the ops somehow tell the remote controller that it can
proceed with the recovery?

> +};
> +
> /**
> * struct rproc_ops - platform-specific device handlers
> * @start: power on the device and boot it
> @@ -459,6 +476,9 @@ struct rproc_dump_segment {
> * @firmware: name of firmware file to be loaded
> * @priv: private data which belongs to the platform-specific rproc module
> * @ops: platform-specific start/stop rproc handlers
> + * @sync_ops: platform-specific start/stop rproc handlers when
> + * synchronising with a remote processor.
> + * @sync_flags: Determine the rproc_ops to choose in specific states.
> * @dev: virtual device for refcounting and common remoteproc behavior
> * @power: refcount of users who need this rproc powered up
> * @state: state of the device
> @@ -482,6 +502,7 @@ struct rproc_dump_segment {
> * @table_sz: size of @cached_table
> * @has_iommu: flag to indicate if remote processor is behind an MMU
> * @auto_boot: flag to indicate if remote processor should be auto-started
> + * @sync_with_rproc: true if currently synchronising with the rproc
> * @dump_segments: list of segments in the firmware
> * @nb_vdev: number of vdev currently handled by rproc
> */
> @@ -492,6 +513,8 @@ struct rproc {
> const char *firmware;
> void *priv;
> struct rproc_ops *ops;
> + struct rproc_ops *sync_ops;

Do we really need two rproc_ops, given that both are coming from the
platform driver and the sync_flags will define which one to look at?

Can't the platform driver just provide an ops table that works with the
flags it passes?

Regards,
Bjorn

> + struct rproc_sync_flags sync_flags;
> struct device dev;
> atomic_t power;
> unsigned int state;
> @@ -515,6 +538,7 @@ struct rproc {
> size_t table_sz;
> bool has_iommu;
> bool auto_boot;
> + bool sync_with_rproc;
> struct list_head dump_segments;
> int nb_vdev;
> u8 elf_class;
> --
> 2.20.1
>