On 12/14/2017 7:16 PM, Sunil Dutt Undekari wrote:
Can't we have some kind of capability indication that the driver supports each of these flags or not? Otherwise we get into a situation where you just have to try the flag and hope it works, since it doesn't look like drivers are required to error out if they don't support the flag.
Sure Dan . We shall have the support for capability indication from the driver.
No top-post please. The capability indication should be done through the
nl80211 api so I would expect to see a patch for that or just included
in this patch. So maybe in struct wiphy add supported_scan_flags field
and provide that through NL80211_CMD_GET_WIPHY command.
Regards,
Arend
Regards,
Sunil
-----Original Message-----
From: Dan Williams [mailto:dcbw@xxxxxxxxxx]
Sent: Thursday, December 14, 2017 12:40 AM
To: Jouni Malinen <jouni@xxxxxxxxxxxxxxxx>; Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
Cc: linux-wireless@xxxxxxxxxxxxxxx; Sunil Dutt Undekari <usdutt@xxxxxxxxxxxxxxxx>
Subject: Re: [PATCH] nl80211: Introduce scan flags to emphasize requested scan behavior
On Wed, 2017-12-13 at 19:52 +0200, Jouni Malinen wrote:
From: Sunil Dutt <usdutt@xxxxxxxxxxxxxxxx>
This commit defines new scan flags (LOW_SPAN, LOW_POWER,
HIGH_LATENCY)
to emphasize the requested scan behavior for the driver. These flags
are optional and are mutually exclusive. Driver shall resort to
default behavior if a respective flag is not supported. The
implementation of the respective functionality can be driver/hardware
specific.
Can't we have some kind of capability indication that the driver supports each of these flags or not? Otherwise we get into a situation where you just have to try the flag and hope it works, since it doesn't look like drivers are required to error out if they don't support the flag.
Dan
These flags can be used to control the compromise between how long a
scan takes, how much power it uses, and high accurate/complete the
scan is in finding the BSSs.
Signed-off-by: Sunil Dutt <usdutt@xxxxxxxxxxxxxxxx>
Signed-off-by: Jouni Malinen <jouni@xxxxxxxxxxxxxxxx>
---
include/uapi/linux/nl80211.h | 23 ++++++++++++++++++++++-
1 file changed, 22 insertions(+), 1 deletion(-)
diff --git a/include/uapi/linux/nl80211.h
b/include/uapi/linux/nl80211.h index 6dd6939..68fdb95 100644
--- a/include/uapi/linux/nl80211.h
+++ b/include/uapi/linux/nl80211.h
@@ -5059,6 +5059,11 @@ enum nl80211_timeout_reason {
* of NL80211_CMD_TRIGGER_SCAN and NL80211_CMD_START_SCHED_SCAN
* requests.
*
+ * NL80211_SCAN_FLAG_LOW_SPAN, NL80211_SCAN_FLAG_LOW_POWER, and
+ * NL80211_SCAN_FLAG_HIGH_ACCURACY flags are exclusive of each
other, i.e., only
+ * one of them can be used in the request. If the driver does not
support the
+ * requested behavior, default scan behavior will be used instead.
+ *
* @NL80211_SCAN_FLAG_LOW_PRIORITY: scan request has low priority
* @NL80211_SCAN_FLAG_FLUSH: flush cache before scanning
* @NL80211_SCAN_FLAG_AP: force a scan even if the interface is
configured @@ -5086,7 +5091,20 @@ enum nl80211_timeout_reason {
* and suppression (if it has received a broadcast Probe
Response frame,
* Beacon frame or FILS Discovery frame from an AP that the
STA considers
* a suitable candidate for (re-)association - suitable in
terms of
- * SSID and/or RSSI
+ * SSID and/or RSSI.
+ * @NL80211_SCAN_FLAG_LOW_SPAN: Span corresponds to the total time
taken to
+ * accomplish the scan. Thus, this flag intends the driver to
perform the
+ * scan request with lesser span/duration. It is specific to
the driver
+ * implementations on how this is accomplished. Scan accuracy
may get
+ * impacted with this flag. This flag cannot be used with
+ * @NL80211_SCAN_FLAG_LOW_POWER: This flag intends the scan attempts
to consume
+ * optimal possible power. Drivers can resort to their
specific means to
+ * optimize the power. Scan accuracy may get impacted with
this flag.
+ * @NL80211_SCAN_FLAG_HIGH_ACCURACY: Accuracy here intends to the
extent of scan
+ * results obtained. Thus HIGH_ACCURACY scan flag aims to get
maximum
+ * possible scan results. This flag hints the driver to use
the best
+ * possible scan configuration to improve the accuracy in
scanning.
+ * Latency and power use may get impacted with this flag.
*/
enum nl80211_scan_flags {
NL80211_SCAN_FLAG_LOW_PRIORITY
= 1<<0,
@@ -5097,6 +5115,9 @@ enum nl80211_scan_flags {
NL80211_SCAN_FLAG_ACCEPT_BCAST_PROBE_RESP =
1<<5,
NL80211_SCAN_FLAG_OCE_PROBE_REQ_HIGH_TX_RATE
= 1<<6,
NL80211_SCAN_FLAG_OCE_PROBE_REQ_DEFERRAL_SUPPRESSION
= 1<<7,
+ NL80211_SCAN_FLAG_LOW_SPAN =
1<<8,
+ NL80211_SCAN_FLAG_LOW_POWER =
1<<9,
+ NL80211_SCAN_FLAG_HIGH_ACCURACY
= 1<<10,
};
/**
