[PATCH 5.7 363/393] PM / devfreq: rk3399_dmc: Fix kernel oops when rockchip,pmu is absent

From: Greg Kroah-Hartman
Date: Mon Aug 17 2020 - 14:40:45 EST


From: Marc Zyngier <maz@xxxxxxxxxx>

commit 63ef91f24f9bfc70b6446319f6cabfd094481372 upstream.

Booting a recent kernel on a rk3399-based system (nanopc-t4),
equipped with a recent u-boot and ATF results in an Oops due
to a NULL pointer dereference.

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.

Cc: stable@xxxxxxxxxxxxxxx
Fixes: 9173c5ceb035 ("PM / devfreq: rk3399_dmc: Pass ODT and auto power down parameters to TF-A.")
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
Signed-off-by: Chanwoo Choi <cw00.choi@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/devfreq/rk3399_dmc.c | 42 +++++++++++++++++++++++-------------------
1 file changed, 23 insertions(+), 19 deletions(-)

--- a/drivers/devfreq/rk3399_dmc.c
+++ b/drivers/devfreq/rk3399_dmc.c
@@ -95,18 +95,20 @@ static int rk3399_dmcfreq_target(struct

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 p
}

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 p
goto err_edev;
};

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