mpr: Add workaround for too few slots being automatically scanned

This patch adds a /boot/loader.conf setting that makes it possibly to
override the detected number of slots in storage enclosures. Some (yes
I'm looking at you HPE D6020!) reports less available slots that there
actually are (the D6020 seems to report 18 but actually has 35 per
drawer). This causes the mpr driver to have problems detecting/managing
all drives in a multienclosure setting. For the D6020 this occurs when
connecting two or more fully equipped (140 drives) enclosures to one
controller...

This problem can be "fixed" by adding the following to /boot/loader.conf
and rebooting:
    hw.mpr.encl_min_slots="35"

Note: I (Warner) don't have this hardware to see if there's some way to
fix the detection, so I'm committing this as a stop-gap. It's a no-op if
no tunable is set.

PR: 271238
Reivewed by: imp

Author: ptrrkssn

sys/dev/mpr/mpr.c

@@ -1729,6 +1729,7 @@ mpr_get_tunables(struct mpr_softc *sc)
 	sc->enable_ssu = MPR_SSU_ENABLE_SSD_DISABLE_HDD;
 	sc->spinup_wait_time = DEFAULT_SPINUP_WAIT;
 	sc->use_phynum = 1;
+	sc->encl_min_slots = 0;
 	sc->max_reqframes = MPR_REQ_FRAMES;
 	sc->max_prireqframes = MPR_PRI_REQ_FRAMES;
 	sc->max_replyframes = MPR_REPLY_FRAMES;
@@ -1748,6 +1749,7 @@ mpr_get_tunables(struct mpr_softc *sc)
 	TUNABLE_INT_FETCH("hw.mpr.enable_ssu", &sc->enable_ssu);
 	TUNABLE_INT_FETCH("hw.mpr.spinup_wait_time", &sc->spinup_wait_time);
 	TUNABLE_INT_FETCH("hw.mpr.use_phy_num", &sc->use_phynum);
+	TUNABLE_INT_FETCH("hw.mpr.encl_min_slots", &sc->encl_min_slots);
 	TUNABLE_INT_FETCH("hw.mpr.max_reqframes", &sc->max_reqframes);
 	TUNABLE_INT_FETCH("hw.mpr.max_prireqframes", &sc->max_prireqframes);
 	TUNABLE_INT_FETCH("hw.mpr.max_replyframes", &sc->max_replyframes);
@@ -1797,6 +1799,10 @@ mpr_get_tunables(struct mpr_softc *sc)
 	    device_get_unit(sc->mpr_dev));
 	TUNABLE_INT_FETCH(tmpstr, &sc->use_phynum);
 
+	snprintf(tmpstr, sizeof(tmpstr), "dev.mpr.%d.encl_min_slots",
+	    device_get_unit(sc->mpr_dev));
+	TUNABLE_INT_FETCH(tmpstr, &sc->encl_min_slots);
+
 	snprintf(tmpstr, sizeof(tmpstr), "dev.mpr.%d.max_reqframes",
 	    device_get_unit(sc->mpr_dev));
 	TUNABLE_INT_FETCH(tmpstr, &sc->max_reqframes);
@@ -1951,6 +1957,10 @@ mpr_setup_sysctl(struct mpr_softc *sc)
 	SYSCTL_ADD_UQUAD(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree),
 	    OID_AUTO, "prp_page_alloc_fail", CTLFLAG_RD,
 	    &sc->prp_page_alloc_fail, "PRP page allocation failures");
+
+	SYSCTL_ADD_INT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree),
+	    OID_AUTO, "encl_min_slots", CTLFLAG_RW, &sc->encl_min_slots, 0,
+	    "force enclosure minimum slots");
 }
 
 static struct mpr_debug_string {

sys/dev/mpr/mpr_mapping.c

@@ -2785,6 +2785,8 @@ mpr_mapping_enclosure_dev_status_change_event(struct mpr_softc *sc,
 		 * DPM, if it's being used.
 		 */
 		if (enc_idx != MPR_ENCTABLE_BAD_IDX) {
+			u16 new_num_slots;
+
 			et_entry = &sc->enclosure_table[enc_idx];
 			if (et_entry->init_complete &&
 			    !et_entry->missing_count) {
@@ -2796,6 +2798,17 @@ mpr_mapping_enclosure_dev_status_change_event(struct mpr_softc *sc,
 			et_entry->enc_handle = le16toh(event_data->
 			    EnclosureHandle);
 			et_entry->start_slot = le16toh(event_data->StartSlot);
+			new_num_slots = le16toh(event_data->NumSlots);
+			if (new_num_slots < sc->encl_min_slots) {
+				mpr_dprint(sc, MPR_MAPPING, "%s: Enclosure %d num_slots %d, overriding with %d.\n",
+					   __func__, enc_idx, new_num_slots, sc->encl_min_slots);
+				new_num_slots = sc->encl_min_slots;
+			}
+			if (et_entry->num_slots != new_num_slots) {
+				mpr_dprint(sc, MPR_MAPPING, "%s: Enclosure %d old num_slots %d, new %d.\n",
+					   __func__, enc_idx, et_entry->num_slots, sc->encl_min_slots);
+				et_entry->num_slots = new_num_slots;
+			}
 			saved_phy_bits = et_entry->phy_bits;
 			et_entry->phy_bits |= le32toh(event_data->PhyBits);
 			if (saved_phy_bits != et_entry->phy_bits)
@@ -2858,6 +2871,11 @@ mpr_mapping_enclosure_dev_status_change_event(struct mpr_softc *sc,
 			et_entry->start_index = MPR_MAPTABLE_BAD_IDX;
 			et_entry->dpm_entry_num = MPR_DPM_BAD_IDX;
 			et_entry->num_slots = le16toh(event_data->NumSlots);
+			if (et_entry->num_slots < sc->encl_min_slots) {
+				mpr_dprint(sc, MPR_ERROR | MPR_MAPPING, "%s: Enclosure %d num_slots is %d, overriding with %d.\n",
+					   __func__, enc_idx, et_entry->num_slots, sc->encl_min_slots);
+				et_entry->num_slots = sc->encl_min_slots;
+			}
 			et_entry->start_slot = le16toh(event_data->StartSlot);
 			et_entry->phy_bits = le32toh(event_data->PhyBits);
 		}

sys/dev/mpr/mprvar.h

@@ -366,6 +366,7 @@ struct mpr_softc {
 	int				spinup_wait_time;
 	int				use_phynum;
 	int				dump_reqs_alltypes;
+	int                             encl_min_slots;
 	uint64_t			chain_alloc_fail;
 	uint64_t			prp_page_alloc_fail;
 	struct sysctl_ctx_list		sysctl_ctx;