Re: [PATCH 03/15] firmware: arm_scmi: Skip protocol initialisation for additional devices

From: Cristian Marussi
Date: Tue Dec 10 2019 - 13:14:51 EST


On 10/12/2019 14:53, Sudeep Holla wrote:
> The scmi bus now supports adding multiple devices per protocol,
> and since scmi_protocol_init is called for each scmi device created,
> we must avoid allocating protocol private data and initialising the
> protocol itself if it is already initialised.
>
> Signed-off-by: Sudeep Holla <sudeep.holla@xxxxxxx>
> ---

Wouldn't be better to add some kind of per-protocol 'initialized' flag somewhere
in the bus abstraction so that the protocol_id itself could be marked as initialized
once bus::scmi_protocol_init() completes successfully so that we could just skip the
invocation itself of bus::scmi_protocol_init() for all the protocols already detected
as initialized ?

Or, if not a flag, maybe deactivating the registered protocol init function itself
once it has been successfully called once .....something along the lines of:

diff --git a/drivers/firmware/arm_scmi/bus.c b/drivers/firmware/arm_scmi/bus.c
index 7a30952b463d..a551a00586c6 100644
--- a/drivers/firmware/arm_scmi/bus.c
+++ b/drivers/firmware/arm_scmi/bus.c
@@ -73,6 +73,8 @@ static int scmi_dev_probe(struct device *dev)
ret = scmi_protocol_init(scmi_dev->protocol_id, scmi_dev->handle);
if (ret)
return ret;
+ idr_replace(&scmi_protocols, dummy_return_0_callback,
+ scmi_dev->protocol_id);

return scmi_drv->probe(scmi_dev);

[not really tested eh ... :D]

This way we can drop this patch as a whole and avoid any future needs to remember
to add this same sort of logic in the next XYZ protocol implementation.

Cheers

Cristian

> drivers/firmware/arm_scmi/clock.c | 3 +++
> drivers/firmware/arm_scmi/perf.c | 3 +++
> drivers/firmware/arm_scmi/power.c | 3 +++
> drivers/firmware/arm_scmi/reset.c | 3 +++
> drivers/firmware/arm_scmi/sensors.c | 3 +++
> 5 files changed, 15 insertions(+)
>
> diff --git a/drivers/firmware/arm_scmi/clock.c b/drivers/firmware/arm_scmi/clock.c
> index 32526a793f3a..922b22aaaf84 100644
> --- a/drivers/firmware/arm_scmi/clock.c
> +++ b/drivers/firmware/arm_scmi/clock.c
> @@ -316,6 +316,9 @@ static int scmi_clock_protocol_init(struct scmi_handle *handle)
> int clkid, ret;
> struct clock_info *cinfo;
>
> + if (handle->clk_ops && handle->clk_priv)
> + return 0; /* initialised already for the first device */
> +
> scmi_version_get(handle, SCMI_PROTOCOL_CLOCK, &version);
>
> dev_dbg(handle->dev, "Clock Version %d.%d\n",
> diff --git a/drivers/firmware/arm_scmi/perf.c b/drivers/firmware/arm_scmi/perf.c
> index 601af4edad5e..55c2a4c21ccb 100644
> --- a/drivers/firmware/arm_scmi/perf.c
> +++ b/drivers/firmware/arm_scmi/perf.c
> @@ -710,6 +710,9 @@ static int scmi_perf_protocol_init(struct scmi_handle *handle)
> u32 version;
> struct scmi_perf_info *pinfo;
>
> + if (handle->perf_ops && handle->perf_priv)
> + return 0; /* initialised already for the first device */
> +
> scmi_version_get(handle, SCMI_PROTOCOL_PERF, &version);
>
> dev_dbg(handle->dev, "Performance Version %d.%d\n",
> diff --git a/drivers/firmware/arm_scmi/power.c b/drivers/firmware/arm_scmi/power.c
> index 5abef7079c0a..9a7593238b8f 100644
> --- a/drivers/firmware/arm_scmi/power.c
> +++ b/drivers/firmware/arm_scmi/power.c
> @@ -185,6 +185,9 @@ static int scmi_power_protocol_init(struct scmi_handle *handle)
> u32 version;
> struct scmi_power_info *pinfo;
>
> + if (handle->power_ops && handle->power_priv)
> + return 0; /* initialised already for the first device */
> +
> scmi_version_get(handle, SCMI_PROTOCOL_POWER, &version);
>
> dev_dbg(handle->dev, "Power Version %d.%d\n",
> diff --git a/drivers/firmware/arm_scmi/reset.c b/drivers/firmware/arm_scmi/reset.c
> index ab42c21c5517..809dc8faee1e 100644
> --- a/drivers/firmware/arm_scmi/reset.c
> +++ b/drivers/firmware/arm_scmi/reset.c
> @@ -195,6 +195,9 @@ static int scmi_reset_protocol_init(struct scmi_handle *handle)
> u32 version;
> struct scmi_reset_info *pinfo;
>
> + if (handle->reset_ops && handle->reset_priv)
> + return 0; /* initialised already for the first device */
> +
> scmi_version_get(handle, SCMI_PROTOCOL_RESET, &version);
>
> dev_dbg(handle->dev, "Reset Version %d.%d\n",
> diff --git a/drivers/firmware/arm_scmi/sensors.c b/drivers/firmware/arm_scmi/sensors.c
> index a400ea805fc2..b7f92c37c8a4 100644
> --- a/drivers/firmware/arm_scmi/sensors.c
> +++ b/drivers/firmware/arm_scmi/sensors.c
> @@ -276,6 +276,9 @@ static int scmi_sensors_protocol_init(struct scmi_handle *handle)
> u32 version;
> struct sensors_info *sinfo;
>
> + if (handle->sensor_ops && handle->sensor_priv)
> + return 0; /* initialised already for the first device */
> +
> scmi_version_get(handle, SCMI_PROTOCOL_SENSOR, &version);
>
> dev_dbg(handle->dev, "Sensor Version %d.%d\n",
> --
> 2.17.1
>