[PATCH] firmware: arm_scmi: Fix SCMI Generic Power Domain probing

From: Cristian Marussi <cristian.marussi@arm.com>
To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Cc: sudeep.holla@arm.com, lukasz.luba@arm.com,
	james.quinlan@broadcom.com, Jonathan.Cameron@Huawei.com,
	cristian.marussi@arm.com
Subject: [PATCH] firmware: arm_scmi: Fix SCMI Generic Power Domain probing
Date: Fri, 19 Jun 2020 23:03:30 +0100	[thread overview]
Message-ID: <20200619220330.12217-1-cristian.marussi@arm.com> (raw)

When, at probe time, an SCMI communication failure inhibits the capacity to
query power domains states, such domains should be skipped.

Registering partially initialized SCMI Power Domains with GenPD causes a
Kernel panic.

[  292.593774] arm-scmi firmware:scmi: timed out in resp(caller: scmi_power_state_get+0xa4/0xd0)
[  292.602369] scmi-power-domain scmi_dev.2: failed to get state for domain 9
[  292.609366] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
[  292.618190] Mem abort info:
[  292.620982]   ESR = 0x96000006
[  292.624065]   EC = 0x25: DABT (current EL), IL = 32 bits
[  292.629403]   SET = 0, FnV = 0
[  292.632474]   EA = 0, S1PTW = 0
[  292.635641] Data abort info:
[  292.638542]   ISV = 0, ISS = 0x00000006
[  292.642396]   CM = 0, WnR = 0
[  292.645364] user pgtable: 4k pages, 48-bit VAs, pgdp=00000009f3691000
[  292.651838] [0000000000000000] pgd=00000009f1ca0003, p4d=00000009f1ca0003, pud=00000009f35ea003, pmd=0000000000000000
[  292.662504] Internal error: Oops: 96000006 [#1] PREEMPT SMP
[  292.672272] CPU: 2 PID: 381 Comm: bash Not tainted 5.8.0-rc1-00011-gebd118c2cca8 #2
[  292.679938] Hardware name: ARM LTD ARM Juno Development Platform/ARM Juno Development Platform, BIOS EDK II Jan  3 2020
   292.662504] Internal error: Oops: 96000006 [#1] PREEMPT SMP
[  292.702221] pstate: 80000005 (Nzcv daif -PAN -UAO BTYPE=--)
[  292.707803] pc : of_genpd_add_provider_onecell+0x98/0x1f8
[  292.713207] lr : of_genpd_add_provider_onecell+0x48/0x1f8
[  292.718609] sp : ffff80001325bb50
[  292.721922] x29: ffff80001325bb50 x28: ffff000974b28ec0
[  292.727240] x27: ffff000971c11380 x26: ffff80001235b200
[  292.732558] x25: ffff00097eff82c0 x24: 0000000000000001
[  292.737874] x23: 00000000ffffffea x22: ffff00097eff82a8
[  292.743191] x21: ffff80001235b1e0 x20: 0000000000000000
[  292.748507] x19: ffff000974b2c080 x18: 0000000000000010
[  292.753823] x17: 0000000000000000 x16: 0000000000000000
[  292.759140] x15: ffffffffffffffff x14: ffff800012139948
[  292.764456] x13: ffff80009325b817 x12: ffff80001325b81f
[  292.769772] x11: ffff80001215a000 x10: 0000000000000a10
[  292.775089] x9 : ffff800010970e08 x8 : ffff000974e84370
[  292.780405] x7 : 00000000ffffffff x6 : ffff00097ef5c1f0
[  292.785721] x5 : ffff00097ef5c1f0 x4 : 0000000000000000
[  292.791038] x3 : ffff80001235b1e0 x2 : fffffffffffffc28
[  292.796354] x1 : 000000000000000a x0 : ffff000971c11680
[  292.801671] Call trace:
[  292.804117]  of_genpd_add_provider_onecell+0x98/0x1f8
[  292.809173]  scmi_pm_domain_probe+0x174/0x1e8
[  292.813533]  scmi_dev_probe+0x90/0xe0
[  292.817198]  really_probe+0xe4/0x448
[  292.820774]  driver_probe_device+0xfc/0x168
[  292.824961]  device_driver_attach+0x7c/0x88
[  292.829146]  bind_store+0xe8/0x128
[  292.832548]  drv_attr_store+0x2c/0x40
[  292.836214]  sysfs_kf_write+0x4c/0x60
[  292.839876]  kernfs_fop_write+0x114/0x230
[  292.843889]  __vfs_write+0x24/0x50
[  292.847291]  vfs_write+0xbc/0x1e0
[  292.850605]  ksys_write+0x70/0xf8
[  292.853919]  __arm64_sys_write+0x24/0x30
[  292.857844]  el0_svc_common.constprop.3+0x94/0x160
[  292.862638]  do_el0_svc+0x2c/0x98
[  292.865954]  el0_sync_handler+0x148/0x1a8
[  292.869964]  el0_sync+0x158/0x180
[  292.873281] Code: eb1a005f d10f6042 540000c1 1400004e (f941ec42)
[  292.879388] ---[ end trace 0077e182f3135393 ]---
[  292.884007] Kernel panic - not syncing: Fatal exception
[  292.889239] SMP: stopping secondary CPUs
[  292.893347] Kernel Offset: 0x140000 from 0xffff800010000000
[  292.898923] PHYS_OFFSET: 0x80000000
[  292.902411] CPU features: 0x240022,25806087
[  292.906594] Memory Limit: none
[  292.909655] ---[ end Kernel panic - not syncing: Fatal exception ]---

Do not register with GenPD any power domain that failed to be queried.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
---
 drivers/firmware/arm_scmi/scmi_pm_domain.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/firmware/arm_scmi/scmi_pm_domain.c b/drivers/firmware/arm_scmi/scmi_pm_domain.c
index bafbfe358f97..9e44479f0284 100644
--- a/drivers/firmware/arm_scmi/scmi_pm_domain.c
+++ b/drivers/firmware/arm_scmi/scmi_pm_domain.c
@@ -85,7 +85,10 @@ static int scmi_pm_domain_probe(struct scmi_device *sdev)
 	for (i = 0; i < num_domains; i++, scmi_pd++) {
 		u32 state;
 
-		domains[i] = &scmi_pd->genpd;
+		if (handle->power_ops->state_get(handle, i, &state)) {
+			dev_warn(dev, "failed to get state for domain %d\n", i);
+			continue;
+		}
 
 		scmi_pd->domain = i;
 		scmi_pd->handle = handle;
@@ -94,13 +97,10 @@ static int scmi_pm_domain_probe(struct scmi_device *sdev)
 		scmi_pd->genpd.power_off = scmi_pd_power_off;
 		scmi_pd->genpd.power_on = scmi_pd_power_on;
 
-		if (handle->power_ops->state_get(handle, i, &state)) {
-			dev_warn(dev, "failed to get state for domain %d\n", i);
-			continue;
-		}
-
 		pm_genpd_init(&scmi_pd->genpd, NULL,
 			      state == SCMI_POWER_STATE_GENERIC_OFF);
+
+		domains[i] = &scmi_pd->genpd;
 	}
 
 	scmi_pd_data->domains = domains;
-- 
2.17.1

