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sys/iwx: support powersave
On Thu, 12 Feb 2026 09:39:54 +0100,
Stefan Sperling <stsp@stsp.name> wrote:
>
> On Fri, Feb 06, 2026 at 09:52:48PM +0100, Kirill A. Korinsky wrote:
> > On Fri, 06 Feb 2026 20:24:42 +0100,
> > Stuart Henderson <stu@spacehopper.org> wrote:
> > >
> > > On 2026/02/06 19:45, Kirill A. Korinsky wrote:
> > > > No, it follow the same pattern like iwn and wpi: to enable it, someone needs
> > > > to explicity adds powersave into ifconfig args, and -powersave to disable.
> > > >
> > > > But I think I should document in man in this diff that it supports
> > > > powersave, similar with iwn and wpi.
> > >
> > > Those are "older devices" as per
> > >
> > > powersave
> > > Enable 802.11 power saving mode. This option is generally only
> > > relevant to older devices where power saving is disabled by
> > > default. On modern hardware, drivers will ask the firmware to
> > > automatically enable any applicable power-saving features.
> > >
> > > I think some of the older ones were a bit unsure whether it works
> > > properly on all devices (so allowing it to be disabled) but it should
> > > be ok on newer ones..
> > >
> >
> > Now it is disabled by default and should be enabled manually, so it should
> > be safe, isn't it?
>
> Power management in iwm/iwx is not entirely disabled by default at present.
>
> At present the driver is always setting the POWER_SAVE_ENA_MSK bit which
> allows the device to "save power by turning off receiver and transmitter".
> I assume (not having made any measurements) that this does save some battery.
> It is certain that the firmware is doing something with this because while
> monitoring iwx traffic we can see the device sending Null-Data frames to the
> AP with the PM snooze/awake bit toggling on/off. Which is not something our
> net80211 stack could do by itself.
>
> The proposed diff turns this feature off by default because all calls to
> iwx_power_mac_update_mode() are removed (even though this function is not
> deleted with this diff?) and replaced with iwx_set_ps_level() which as far
> as I can tell doesn't get called if the ioctl which enables power management
> does not run. So the proposed diff would probably cost people some battery
> because nobody will bother running the additional command to enable power
> management.
>
> I do think enabling support for legacy power management (DTIM) will have some
> benefits, so I agree with the direction your diff is taking. If you want to
> investigate further, on modern wifi networks there are additional
> possibilities. See here for an overview of the state of the art in 2014:
> https://mrncciew.com/2014/10/14/cwap-802-11-power-management/
>
> There are probably even more features in modern standards but the intel
> firmware supports all the important 2014 features mentioned there and
> we leave them all disabled at present apart from POWER_SAVE_ENA_MSK.
>
> DTIM power management is a good start. Also supporting uAPSD and SMSP would
> probably help save power quite a bit more. These newer features depend on
> negotiation with the AP so having them be controlled by an ioctl which forces
> PM on or off makes zero sense.
>
> The only use case I see for the ioctl would be to disable all power
> management when using an AP such as ral(4) which cannot handle clients
> using DTIM. At this point most APs in active use should be able to handle
> DTIM power management as enabled by your patch (smartphones would not have
> working wifi otherwise), if not also uAPSD and SMSP, etc.
> So if we're going to be making use of this it should be done by default.
>
> By the way, I have quite a bit of diffs built up in order to support
> BZ devices which is still work in progress and might clash a little
> bit with your diffs, but not very much.
>
Thanks for the link and feedback.
Here an updated patch with in this direction.
I did not touch uAPSD, advanced PM flags, SMPS, or misbehaving-AP fallback.
The change set is already relatively large, so I prefer to move by small steps.
This patch enables power save by default for iwx by setting
IEEE80211_F_PMGTON (and IEEE80211_C_PMGT), and makes iwx react to
SIOCS80211POWER by switching between PM (level 3) and CAM at runtime.
Index: share/man/man4/iwx.4
===================================================================
RCS file: /home/cvs/src/share/man/man4/iwx.4,v
diff -u -p -r1.22 iwx.4
--- share/man/man4/iwx.4 1 Dec 2025 16:44:13 -0000 1.22
+++ share/man/man4/iwx.4 6 Feb 2026 18:33:51 -0000
@@ -76,7 +76,7 @@ driver supports protected management fra
of management frames such as deauthentication, disassociation, and block-ack
negotiation, on networks using WPA.
.Pp
-In BSS mode the driver supports background scanning;
+In BSS mode the driver supports powersave mode and background scanning;
see
.Xr ifconfig 8 .
.Pp
Index: sys/dev/pci/if_iwx.c
===================================================================
RCS file: /home/cvs/src/sys/dev/pci/if_iwx.c,v
diff -u -p -r1.197 if_iwx.c
--- sys/dev/pci/if_iwx.c 11 Feb 2026 11:14:53 -0000 1.197
+++ sys/dev/pci/if_iwx.c 14 Feb 2026 18:13:13 -0000
@@ -402,10 +402,7 @@ int iwx_flush_sta(struct iwx_softc *, st
int iwx_beacon_filter_send_cmd(struct iwx_softc *,
struct iwx_beacon_filter_cmd *);
int iwx_update_beacon_abort(struct iwx_softc *, struct iwx_node *, int);
-void iwx_power_build_cmd(struct iwx_softc *, struct iwx_node *,
- struct iwx_mac_power_cmd *);
-int iwx_power_mac_update_mode(struct iwx_softc *, struct iwx_node *);
-int iwx_power_update_device(struct iwx_softc *);
+int iwx_set_pslevel(struct iwx_softc *, int, int, int);
int iwx_enable_beacon_filter(struct iwx_softc *, struct iwx_node *);
int iwx_disable_beacon_filter(struct iwx_softc *);
int iwx_add_sta_cmd(struct iwx_softc *, struct iwx_node *, int);
@@ -6620,68 +6617,80 @@ iwx_update_beacon_abort(struct iwx_softc
return iwx_beacon_filter_send_cmd(sc, &cmd);
}
-void
-iwx_power_build_cmd(struct iwx_softc *sc, struct iwx_node *in,
- struct iwx_mac_power_cmd *cmd)
+int
+iwx_set_pslevel(struct iwx_softc *sc, int dtim, int level, int async)
{
struct ieee80211com *ic = &sc->sc_ic;
- struct ieee80211_node *ni = &in->in_ni;
+ struct iwx_device_power_cmd dcmd = { };
+ struct iwx_mac_power_cmd mcmd;
+ struct iwx_node *in;
+ struct ieee80211_node *ni;
+ const struct iwx_pmgt *pmgt;
+ int range, skip_dtim, cmd_flags, err;
int dtim_period, dtim_msec, keep_alive;
- cmd->id_and_color = htole32(IWX_FW_CMD_ID_AND_COLOR(in->in_id,
- in->in_color));
- if (ni->ni_dtimperiod)
- dtim_period = ni->ni_dtimperiod;
- else
- dtim_period = 1;
-
- /*
- * Regardless of power management state the driver must set
- * keep alive period. FW will use it for sending keep alive NDPs
- * immediately after association. Check that keep alive period
- * is at least 3 * DTIM.
- */
- dtim_msec = dtim_period * ni->ni_intval;
- keep_alive = MAX(3 * dtim_msec, 1000 * IWX_POWER_KEEP_ALIVE_PERIOD_SEC);
- keep_alive = roundup(keep_alive, 1000) / 1000;
- cmd->keep_alive_seconds = htole16(keep_alive);
+ if (ic->ic_opmode == IEEE80211_M_MONITOR)
+ return 0;
- if (ic->ic_opmode != IEEE80211_M_MONITOR)
- cmd->flags = htole16(IWX_POWER_FLAGS_POWER_SAVE_ENA_MSK);
-}
+ if (dtim == 0) {
+ dtim = 1;
+ skip_dtim = 0;
+ } else
+ skip_dtim = -1;
-int
-iwx_power_mac_update_mode(struct iwx_softc *sc, struct iwx_node *in)
-{
- int err;
- int ba_enable;
- struct iwx_mac_power_cmd cmd;
+ if (dtim <= 2)
+ range = 0;
+ else if (dtim <= 10)
+ range = 1;
+ else
+ range = 2;
- memset(&cmd, 0, sizeof(cmd));
+ pmgt = &iwx_pmgt[range][level];
+ if (skip_dtim == -1)
+ skip_dtim = pmgt->skip_dtim;
- iwx_power_build_cmd(sc, in, &cmd);
+ if (level != 0)
+ dcmd.flags = htole16(IWX_DEVICE_POWER_FLAGS_POWER_SAVE_ENA_MSK);
- err = iwx_send_cmd_pdu(sc, IWX_MAC_PM_POWER_TABLE, 0,
- sizeof(cmd), &cmd);
- if (err != 0)
+ cmd_flags = async ? IWX_CMD_ASYNC : 0;
+ err = iwx_send_cmd_pdu(sc, IWX_POWER_TABLE_CMD, cmd_flags,
+ sizeof(dcmd), &dcmd);
+ if (err)
return err;
- ba_enable = !!(cmd.flags &
- htole16(IWX_POWER_FLAGS_POWER_MANAGEMENT_ENA_MSK));
- return iwx_update_beacon_abort(sc, in, ba_enable);
-}
+ if ((sc->sc_flags & IWX_FLAG_MAC_ACTIVE) == 0)
+ return 0;
-int
-iwx_power_update_device(struct iwx_softc *sc)
-{
- struct iwx_device_power_cmd cmd = { };
- struct ieee80211com *ic = &sc->sc_ic;
+ in = (void *)ic->ic_bss;
+ ni = &in->in_ni;
- if (ic->ic_opmode != IEEE80211_M_MONITOR)
- cmd.flags = htole16(IWX_DEVICE_POWER_FLAGS_POWER_SAVE_ENA_MSK);
+ memset(&mcmd, 0, sizeof(mcmd));
+ mcmd.id_and_color = htole32(IWX_FW_CMD_ID_AND_COLOR(in->in_id,
+ in->in_color));
+ dtim_period = ni->ni_dtimperiod ? ni->ni_dtimperiod : 1;
+ dtim_msec = dtim_period * ni->ni_intval;
+ keep_alive = MAX(3 * dtim_msec, 1000 * IWX_POWER_KEEP_ALIVE_PERIOD_SEC);
+ keep_alive = roundup(keep_alive, 1000) / 1000;
+ mcmd.keep_alive_seconds = htole16(keep_alive);
- return iwx_send_cmd_pdu(sc,
- IWX_POWER_TABLE_CMD, 0, sizeof(cmd), &cmd);
+ if (level != 0) {
+ mcmd.flags = htole16(IWX_POWER_FLAGS_POWER_SAVE_ENA_MSK |
+ IWX_POWER_FLAGS_POWER_MANAGEMENT_ENA_MSK);
+ mcmd.rx_data_timeout = htole32(pmgt->rxtimeout * 1024);
+ mcmd.tx_data_timeout = htole32(pmgt->txtimeout * 1024);
+ if (skip_dtim != 0) {
+ mcmd.flags |= htole16(IWX_POWER_FLAGS_SKIP_OVER_DTIM_MSK);
+ mcmd.skip_dtim_periods = skip_dtim + 1;
+ }
+ }
+
+ err = iwx_send_cmd_pdu(sc, IWX_MAC_PM_POWER_TABLE, cmd_flags,
+ sizeof(mcmd), &mcmd);
+ if (err != 0)
+ return err;
+
+ return iwx_update_beacon_abort(sc, in, !!(mcmd.flags &
+ htole16(IWX_POWER_FLAGS_POWER_MANAGEMENT_ENA_MSK)));
}
int
@@ -8712,7 +8721,8 @@ iwx_run(struct iwx_softc *sc)
return err;
}
- err = iwx_power_update_device(sc);
+ err = iwx_set_pslevel(sc, 0,
+ (ic->ic_flags & IEEE80211_F_PMGTON) ? 3 : 0, 1);
if (err) {
printf("%s: could not send power command (error %d)\n",
DEVNAME(sc), err);
@@ -8734,13 +8744,6 @@ iwx_run(struct iwx_softc *sc)
if (ic->ic_opmode == IEEE80211_M_MONITOR)
return 0;
- err = iwx_power_mac_update_mode(sc, in);
- if (err) {
- printf("%s: could not update MAC power (error %d)\n",
- DEVNAME(sc), err);
- return err;
- }
-
/* Start at lowest available bit-rate. Firmware will raise. */
in->in_ni.ni_txrate = 0;
in->in_ni.ni_txmcs = 0;
@@ -9632,7 +9635,8 @@ iwx_init_hw(struct iwx_softc *sc)
goto err;
}
- err = iwx_power_update_device(sc);
+ err = iwx_set_pslevel(sc, 0,
+ (ic->ic_flags & IEEE80211_F_PMGTON) ? 3 : 0, 0);
if (err) {
printf("%s: could not send power command (error %d)\n",
DEVNAME(sc), err);
@@ -9986,6 +9990,7 @@ int
iwx_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
{
struct iwx_softc *sc = ifp->if_softc;
+ struct ieee80211com *ic = &sc->sc_ic;
int s, err = 0, generation = sc->sc_generation;
/*
@@ -10018,6 +10023,21 @@ iwx_ioctl(struct ifnet *ifp, u_long cmd,
}
break;
+ case SIOCS80211POWER:
+ err = ieee80211_ioctl(ifp, cmd, data);
+ if (err != ENETRESET)
+ break;
+ if (ic->ic_state == IEEE80211_S_RUN) {
+ if (ic->ic_flags & IEEE80211_F_PMGTON)
+ err = iwx_set_pslevel(sc, 0, 3, 0);
+ else /* back to CAM */
+ err = iwx_set_pslevel(sc, 0, 0, 0);
+ } else {
+ /* Defer until transition to IEEE80211_S_RUN. */
+ err = 0;
+ }
+ break;
+
default:
err = ieee80211_ioctl(ifp, cmd, data);
}
@@ -11902,6 +11922,7 @@ iwx_attach(struct device *parent, struct
ic->ic_caps =
IEEE80211_C_QOS | IEEE80211_C_TX_AMPDU | /* A-MPDU */
IEEE80211_C_ADDBA_OFFLOAD | /* device sends ADDBA/DELBA frames */
+ IEEE80211_C_PMGT | /* power management */
IEEE80211_C_WEP | /* WEP */
IEEE80211_C_RSN | /* WPA/RSN */
IEEE80211_C_SCANALL | /* device scans all channels at once */
@@ -11910,6 +11931,7 @@ iwx_attach(struct device *parent, struct
IEEE80211_C_SHSLOT | /* short slot time supported */
IEEE80211_C_SHPREAMBLE | /* short preamble supported */
IEEE80211_C_MFP; /* management frame protection */
+ ic->ic_flags |= IEEE80211_F_PMGTON;
ic->ic_htcaps = IEEE80211_HTCAP_SGI20 | IEEE80211_HTCAP_SGI40;
ic->ic_htcaps |= IEEE80211_HTCAP_CBW20_40;
Index: sys/dev/pci/if_iwxreg.h
===================================================================
RCS file: /home/cvs/src/sys/dev/pci/if_iwxreg.h,v
diff -u -p -r1.58 if_iwxreg.h
--- sys/dev/pci/if_iwxreg.h 1 Dec 2025 16:44:13 -0000 1.58
+++ sys/dev/pci/if_iwxreg.h 30 Jan 2026 23:52:35 -0000
@@ -5096,6 +5096,42 @@ struct iwx_mac_power_cmd {
#define IWX_DEFAULT_PS_TX_DATA_TIMEOUT (100 * 1000)
#define IWX_DEFAULT_PS_RX_DATA_TIMEOUT (100 * 1000)
+#define IWX_NDTIMRANGES 3
+#define IWX_NPOWERLEVELS 6
+static const struct iwx_pmgt {
+ uint32_t rxtimeout;
+ uint32_t txtimeout;
+ int skip_dtim;
+} iwx_pmgt[IWX_NDTIMRANGES][IWX_NPOWERLEVELS] = {
+ /* DTIM <= 2 */
+ {
+ { 0, 0, 0 }, /* CAM */
+ { 200, 500, 0 }, /* PS level 1 */
+ { 200, 300, 0 }, /* PS level 2 */
+ { 50, 100, 0 }, /* PS level 3 */
+ { 50, 25, 1 }, /* PS level 4 */
+ { 25, 25, 2 } /* PS level 5 */
+ },
+ /* 3 <= DTIM <= 10 */
+ {
+ { 0, 0, 0 }, /* CAM */
+ { 200, 500, 0 }, /* PS level 1 */
+ { 200, 300, 0 }, /* PS level 2 */
+ { 50, 100, 0 }, /* PS level 3 */
+ { 50, 25, 1 }, /* PS level 4 */
+ { 25, 25, 2 } /* PS level 5 */
+ },
+ /* DTIM >= 11 */
+ {
+ { 0, 0, 0 }, /* CAM */
+ { 200, 500, 0 }, /* PS level 1 */
+ { 200, 300, 0 }, /* PS level 2 */
+ { 50, 100, 0 }, /* PS level 3 */
+ { 50, 25, 0 }, /* PS level 4 */
+ { 25, 25, 0 } /* PS level 5 */
+ }
+};
+
/*
* struct iwx_uapsd_misbehaving_ap_notif - FW sends this notification when
* associated AP is identified as improperly implementing uAPSD protocol.
sys/iwx: support powersave