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Commit ee2f2074 authored by Mitchell Tasman's avatar Mitchell Tasman Committed by Greg Kroah-Hartman
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greybus: svc: reconfig APBridgeA-Switch link to handle required load 



SW-4894, SW-4389, and share a common root cause, namely that
the power-on reset configuration of the APBridgeA-Switch link of PWM
Gear 1, 1 Lane, Slow Auto, is insufficient to handle some required
traffic loads, such as 3 audio streams plus boot-over-UniPro or 4 audio
streams.

The correct long-term solution is to implement a UniPro Power Mode
Manager as in that considers the demands placed on the network,
and adjusts power modes accordingly.

The present commit implements a short-term, brute-force hack to allow
continued system testing:
- Upon receiving an SVC HELLO request, schedule deferred work to
  reconfigure the APB1-Switch link to PWM G2, 1 lane, Slow Auto
- When the Camera driver transitions a White Camera module from active to
  inactive, return the APB1-Switch link to PWM G2, 1 lane, Slow Auto

The Camera driver already steps up the APBridgeA-Camera link speed while a
camera module is active, which affords sufficient margin for simultaneous
audio and hotplug activity, and the Camera driver already steps down the
link speed thereafter: the change made by the present patch is simply to
tweak the stepped-down power mode to match the new baseline configuration.

Signed-off-by: default avatarMitchell Tasman <tasman@leaflabs.com>
Tested-by: default avatarMark Greer <mgreer@animalcreek.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@google.com>
parent 3e29bcf4

drivers/staging/greybus/camera.c

+2 −2
Original line number Diff line number Diff line
@@ -131,9 +131,9 @@ static int gb_camera_set_intf_power_mode(struct gb_camera *gcam, u8 intf_id, 
		ret = gb_svc_intf_set_power_mode(svc, intf_id,

						 GB_SVC_UNIPRO_HS_SERIES_A,

						 GB_SVC_UNIPRO_SLOW_AUTO_MODE,

						 1, 2,

						 2, 1,

						 GB_SVC_UNIPRO_SLOW_AUTO_MODE,

						 1, 2,

						 2, 1,

						 0, 0);



	return ret;

drivers/staging/greybus/svc.c

+35 −1
Original line number Diff line number Diff line
@@ -23,6 +23,8 @@ struct gb_svc_deferred_request { 
};





static int gb_svc_queue_deferred_request(struct gb_operation *operation);



static ssize_t endo_id_show(struct device *dev,

			struct device_attribute *attr, char *buf)

{
@@ -695,7 +697,7 @@ static int gb_svc_hello(struct gb_operation *op) 


	gb_svc_debugfs_init(svc);



	return 0;

	return gb_svc_queue_deferred_request(op);

}



static struct gb_interface *gb_svc_interface_lookup(struct gb_svc *svc,
@@ -754,6 +756,35 @@ static void gb_svc_intf_reenable(struct gb_svc *svc, struct gb_interface *intf) 
	mutex_unlock(&intf->mutex);

}



static void gb_svc_process_hello_deferred(struct gb_operation *operation)

{

	struct gb_connection *connection = operation->connection;

	struct gb_svc *svc = gb_connection_get_data(connection);

	int ret;



	/*

	 * XXX This is a hack/work-around to reconfigure the APBridgeA-Switch

	 * link to PWM G2, 1 Lane, Slow Auto, so that it has sufficient

	 * bandwidth for 3 audio streams plus boot-over-UniPro of a hot-plugged

	 * module.

	 *

	 * The code should be removed once SW-2217, Heuristic for UniPro

	 * Power Mode Changes is resolved.

	 */

	ret = gb_svc_intf_set_power_mode(svc, svc->ap_intf_id,

					GB_SVC_UNIPRO_HS_SERIES_A,

					GB_SVC_UNIPRO_SLOW_AUTO_MODE,

					2, 1,

					GB_SVC_UNIPRO_SLOW_AUTO_MODE,

					2, 1,

					0, 0);



	if (ret)

		dev_warn(&svc->dev,

			"power mode change failed on AP to switch link: %d\n",

			ret);

}



static void gb_svc_process_intf_hotplug(struct gb_operation *operation)

{

	struct gb_svc_intf_hotplug_request *request;
@@ -963,6 +994,9 @@ static void gb_svc_process_deferred_request(struct work_struct *work) 
	type = operation->request->header->type;



	switch (type) {

	case GB_SVC_TYPE_SVC_HELLO:

		gb_svc_process_hello_deferred(operation);

		break;

	case GB_SVC_TYPE_INTF_HOTPLUG:

		gb_svc_process_intf_hotplug(operation);

		break;