[PATCH v2] PM / devfreq: rk3399_dmc: Fix kernel oops when rockchip,pmu is absent

Marc Zyngier
2020-06-22T15:28:44Z

Booting a recent kernel on a rk3399-based system (nanopc-t4),
equipped with a recent u-boot and ATF results in the following:

[ 5.607431] Unable to handle kernel NULL pointer dereference at virtual address 00000000000001e4
[ 5.608219] Mem abort info:
[ 5.608469] ESR = 0x96000004
[ 5.608749] EC = 0x25: DABT (current EL), IL = 32 bits
[ 5.609223] SET = 0, FnV = 0
[ 5.609600] EA = 0, S1PTW = 0
[ 5.609891] Data abort info:
[ 5.610149] ISV = 0, ISS = 0x00000004
[ 5.610489] CM = 0, WnR = 0
[ 5.610757] user pgtable: 4k pages, 48-bit VAs, pgdp=00000000e62fb000
[ 5.611326] [00000000000001e4] pgd=0000000000000000, p4d=0000000000000000
[ 5.611931] Internal error: Oops: 96000004 [#1] SMP
[ 5.612363] Modules linked in: rockchip_thermal(E+) rk3399_dmc(E+) soundcore(E) dw_wdt(E) rockchip_dfi(E) nvmem_rockchip_efuse(E) pwm_rockchip(E) cfg80211(E+) rockchip_saradc(E) industrialio(E) rfkill(E) cpufreq_dt(E) ip_tables(E) x_tables(E) autofs4(E) ext4(E) crc32c_generic(E) crc16(E) mbcache(E) jbd2(E) realtek(E) nvme(E) nvme_core(E) t10_pi(E) xhci_plat_hcd(E) xhci_hcd(E) rtc_rk808(E) rk808_regulator(E) clk_rk808(E) dwc3(E) udc_core(E) roles(E) ulpi(E) rk808(E) fan53555(E) rockchipdrm(E) analogix_dp(E) dw_hdmi(E) cec(E) dw_mipi_dsi(E) fixed(E) dwc3_of_simple(E) phy_rockchip_emmc(E) gpio_keys(E) drm_kms_helper(E) phy_rockchip_inno_usb2(E) ehci_platform(E) dwmac_rk(E) stmmac_platform(E) phy_rockchip_pcie(E) ohci_platform(E) ohci_hcd(E) rockchip_io_domain(E) stmmac(E) phy_rockchip_typec(E) ehci_hcd(E) sdhci_of_arasan(E) mdio_xpcs(E) sdhci_pltfm(E) cqhci(E) drm(E) sdhci(E) phylink(E) of_mdio(E) usbcore(E) i2c_rk3x(E) dw_mmc_rockchip(E) dw_mmc_pltfm(E) dw_mmc(E) fixed_phy(E) libphy(E)
[ 5.612454] pl330(E)
[ 5.620255] CPU: 1 PID: 270 Comm: systemd-udevd Tainted: G E 5.7.0-13692-g83ae758d8b22 #1157
[ 5.621110] Hardware name: rockchip evb_rk3399/evb_rk3399, BIOS 2020.07-rc4-00023-g10d4cafe0f 06/10/2020
[ 5.621947] pstate: 40000005 (nZcv daif -PAN -UAO BTYPE=--)
[ 5.622446] pc : regmap_read+0x1c/0x80
[ 5.622787] lr : rk3399_dmcfreq_probe+0x6a4/0x8c0 [rk3399_dmc]
[ 5.623299] sp : ffff8000126cb8a0
[ 5.623594] x29: ffff8000126cb8a0 x28: ffff8000126cbdb0
[ 5.624063] x27: ffff0000f22dac40 x26: ffff0000f6779800
[ 5.624533] x25: ffff0000f6779810 x24: 00000000ffffffea
[ 5.625002] x23: 00000000ffffffea x22: ffff0000f65b74c8
[ 5.625471] x21: ffff0000f783ca08 x20: ffff0000f65b7480
[ 5.625941] x19: 0000000000000000 x18: 0000000000000001
[ 5.626410] x17: 0000000000000000 x16: 0000000000000000
[ 5.626878] x15: ffff0000f22db138 x14: ffffffffffffffff
[ 5.627347] x13: 0000000000000018 x12: ffff80001106a8c7
[ 5.627817] x11: 0000000000000003 x10: 0101010101010101
[ 5.627861] systemd[1]: Found device SPCC M.2 PCIE SSD 3.
[ 5.628286] x9 : ffff800008d7c89c x8 : 7f7f7f7f7f7f7f7f
[ 5.629238] x7 : fefefeff646c606d x6 : 1c0e0e0ee3e8e9f0
[ 5.629709] x5 : 706968630e0e0e1c x4 : 8080808000000000
[ 5.630178] x3 : 937b1b5b1b434b80 x2 : ffff8000126cb944
[ 5.630648] x1 : 0000000000000308 x0 : 0000000000000000
[ 5.631119] Call trace:
[ 5.631346] regmap_read+0x1c/0x80
[ 5.631654] rk3399_dmcfreq_probe+0x6a4/0x8c0 [rk3399_dmc]
[ 5.632142] platform_drv_probe+0x5c/0xb0
[ 5.632500] really_probe+0xe4/0x448
[ 5.632819] driver_probe_device+0xfc/0x168
[ 5.633191] device_driver_attach+0x7c/0x88
[ 5.633567] __driver_attach+0xac/0x178
[ 5.633914] bus_for_each_dev+0x78/0xc8
[ 5.634261] driver_attach+0x2c/0x38
[ 5.634582] bus_add_driver+0x14c/0x230
[ 5.634925] driver_register+0x6c/0x128
[ 5.635269] __platform_driver_register+0x50/0x60
[ 5.635692] rk3399_dmcfreq_driver_init+0x2c/0x1000 [rk3399_dmc]
[ 5.636226] do_one_initcall+0x50/0x230
[ 5.636569] do_init_module+0x60/0x248
[ 5.636902] load_module+0x21f8/0x28d8
[ 5.637237] __do_sys_finit_module+0xb0/0x118
[ 5.637627] __arm64_sys_finit_module+0x28/0x38
[ 5.638031] el0_svc_common.constprop.0+0x7c/0x1f8
[ 5.638456] do_el0_svc+0x2c/0x98
[ 5.638754] el0_svc+0x18/0x48
[ 5.639029] el0_sync_handler+0x8c/0x2d4
[ 5.639378] el0_sync+0x158/0x180
[ 5.639680] Code: a9bd7bfd 910003fd a90153f3 aa0003f3 (b941e400)
[ 5.640221] ---[ end trace 63675fe5d0021970 ]---

This turns out to be due to the rk3399-dmc driver looking for
an *undocumented* property (rockchip,pmu), and happily using
a NULL pointer when the property isn't there.

Instead, make most of what was brought in with 9173c5ceb035
("PM / devfreq: rk3399_dmc: Pass ODT and auto power down parameters
to TF-A.") conditioned on finding this property in the device-tree,
preventing the driver from exploding.

Fixes: 9173c5ceb035 ("PM / devfreq: rk3399_dmc: Pass ODT and auto power down parameters to TF-A.")
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
drivers/devfreq/rk3399_dmc.c | 42 ++++++++++++++++++++----------------
1 file changed, 23 insertions(+), 19 deletions(-)

diff --git a/drivers/devfreq/rk3399_dmc.c b/drivers/devfreq/rk3399_dmc.c
index 24f04f78285b..027769e39f9b 100644
--- a/drivers/devfreq/rk3399_dmc.c
+++ b/drivers/devfreq/rk3399_dmc.c
@@ -95,18 +95,20 @@ static int rk3399_dmcfreq_target(struct device *dev, unsigned long *freq,

mutex_lock(&dmcfreq->lock);

- if (target_rate >= dmcfreq->odt_dis_freq)
- odt_enable = true;
-
- /*
- * This makes a SMC call to the TF-A to set the DDR PD (power-down)
- * timings and to enable or disable the ODT (on-die termination)
- * resistors.
- */
- arm_smccc_smc(ROCKCHIP_SIP_DRAM_FREQ, dmcfreq->odt_pd_arg0,
- dmcfreq->odt_pd_arg1,
- ROCKCHIP_SIP_CONFIG_DRAM_SET_ODT_PD,
- odt_enable, 0, 0, 0, &res);
+ if (dmcfreq->regmap_pmu) {
+ if (target_rate >= dmcfreq->odt_dis_freq)
+ odt_enable = true;
+
+ /*
+ * This makes a SMC call to the TF-A to set the DDR PD
+ * (power-down) timings and to enable or disable the
+ * ODT (on-die termination) resistors.
+ */
+ arm_smccc_smc(ROCKCHIP_SIP_DRAM_FREQ, dmcfreq->odt_pd_arg0,
+ dmcfreq->odt_pd_arg1,
+ ROCKCHIP_SIP_CONFIG_DRAM_SET_ODT_PD,
+ odt_enable, 0, 0, 0, &res);
+ }

/*
* If frequency scaling from low to high, adjust voltage first.
@@ -371,13 +373,14 @@ static int rk3399_dmcfreq_probe(struct platform_device *pdev)
}

node = of_parse_phandle(np, "rockchip,pmu", 0);
- if (node) {
- data->regmap_pmu = syscon_node_to_regmap(node);
- of_node_put(node);
- if (IS_ERR(data->regmap_pmu)) {
- ret = PTR_ERR(data->regmap_pmu);
- goto err_edev;
- }
+ if (!node)
+ goto no_pmu;
+
+ data->regmap_pmu = syscon_node_to_regmap(node);
+ of_node_put(node);
+ if (IS_ERR(data->regmap_pmu)) {
+ ret = PTR_ERR(data->regmap_pmu);
+ goto err_edev;
}

regmap_read(data->regmap_pmu, RK3399_PMUGRF_OS_REG2, &val);
@@ -399,6 +402,7 @@ static int rk3399_dmcfreq_probe(struct platform_device *pdev)
goto err_edev;
};

+no_pmu:
arm_smccc_smc(ROCKCHIP_SIP_DRAM_FREQ, 0, 0,
ROCKCHIP_SIP_CONFIG_DRAM_INIT,
0, 0, 0, 0, &res);
--
2.26.2