wifi(hidl): Modify the SAR power levels interface
Modifying the interface used to lower the tx power level for meeting SAR
requirements based on recommendation from the nexus hardware team. The
previous interface passed in a single power value in dBm for meeting SAR
requirements. However, the SAR requirements are more complex than that.
Based on the connection mode (802.11 a,b,g,n,ac) and the number of
streams that are active (MIMO), the SAR power levels are very
different. Using the previous interface would mean that we will have to
use the lowest power level among all the connection modes to meet the SAR
requirements. This would however result in us lowering the power much
more than needed (~2 dBm) for many connection modes.
Instead, we're switching to a more generic interface where the framework
informs the wifi chip that we're entering a special tx power mode scenario
(today, there is only 1 for voice call). The chip can then lookup the
extensive table of power levels for different connection modes which are
pre-populated by the OEM's in the BDF file to set the power level (depending
on the scenario framework sends and the active connection mode).
Bug: 62437848
Test: Manual tests
Change-Id: I5ee3f0d2c130958dbeb352e3b5ad9407f432624f
diff --git a/wifi/1.1/IWifiChip.hal b/wifi/1.1/IWifiChip.hal
index 50cd02d..1af1f71 100644
--- a/wifi/1.1/IWifiChip.hal
+++ b/wifi/1.1/IWifiChip.hal
@@ -1,5 +1,5 @@
/*
- * Copyright 2016 The Android Open Source Project
+ * Copyright 2017 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
@@ -44,24 +44,40 @@
};
/**
- * API to set TX power limit.
- * This is used for meeting SAR requirements while making VOIP calls for
- * example.
- *
- * @param powerInDbm Power level in dBm.
- * @return status WifiStatus of the operation.
- * Possible status codes:
- * |WifiStatusCode.SUCCESS|,
- * |WifiStatusCode.ERROR_WIFI_CHIP_INVALID|,
- * |WifiStatusCode.ERROR_NOT_SUPPORTED|,
- * |WifiStatusCode.NOT_AVAILABLE|,
- * |WifiStatusCode.UNKNOWN|
+ * List of preset wifi radio TX power levels for different scenarios.
+ * The actual power values (typically varies based on the channel,
+ * 802.11 connection type, number of MIMO streams, etc) for each scenario
+ * is defined by the OEM as a BDF file since it varies for each wifi chip
+ * vendor and device.
*/
- setTxPowerLimit(int32_t powerInDbm) generates (WifiStatus status);
+ enum TxPowerScenario : uint32_t {
+ VOICE_CALL = 0,
+ };
/**
- * API to reset TX power limit.
- * This is used to set the power back to default values.
+ * API to select one of the preset TX power scenarios.
+ *
+ * The framework must invoke this method with the appropriate scenario to let
+ * the wifi chip change it's transmitting power levels.
+ * OEM's should define various power profiles for each of the scenarios
+ * above (defined in |TxPowerScenario|).
+ *
+ * @param scenario One of the preselected scenarios defined in
+ * |TxPowerScenario|.
+ * @return status WifiStatus of the operation.
+ * Possible status codes:
+ * |WifiStatusCode.SUCCESS|,
+ * |WifiStatusCode.ERROR_WIFI_CHIP_INVALID|,
+ * |WifiStatusCode.ERROR_NOT_SUPPORTED|,
+ * |WifiStatusCode.NOT_AVAILABLE|,
+ * |WifiStatusCode.UNKNOWN|
+ */
+ selectTxPowerScenario(TxPowerScenario scenario) generates (WifiStatus status);
+
+ /**
+ * API to reset TX power levels.
+ * This is used to indicate the end of the previously selected TX power
+ * scenario and let the wifi chip fall back to the default power values.
*
* @return status WifiStatus of the operation.
* Possible status codes:
@@ -71,5 +87,5 @@
* |WifiStatusCode.NOT_AVAILABLE|,
* |WifiStatusCode.UNKNOWN|
*/
- resetTxPowerLimit() generates (WifiStatus status);
+ resetTxPowerScenario() generates (WifiStatus status);
};