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

On 6/23/20 12:28 AM, Marc Zyngier wrote:
> 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);
>

It looks good to me. But, I think that it is not necessary
fully kernel panic log about NULL pointer. It is enoughspsp
just mentioning the NULL pointer issue without full kernel panic log.

So, how about editing the patch description as following or others simply?
and we need to add 'stable@vger.kernel.org' to Cc list for applying it
to stable branch.


PM / devfreq: rk3399_dmc: Fix kernel oops when rockchip,pmu is absent

Booting a recent kernel on a rk3399-based system (nanopc-t4),
equipped with a recent u-boot and ATF results in the kernel panic
about NULL pointer issue.

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>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>


--
Best Regards,
Chanwoo Choi
Samsung Electronics
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