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 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@vger.kernel.org
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>

diff --git a/drivers/devfreq/rk3399_dmc.c b/drivers/devfreq/rk3399_dmc.c
index 24f04f7..027769e 100644 (file)
--- 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);