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From:   Martin Kaiser <martin@kaiser.cx>
To:     Dong Aisheng <aisheng.dong@nxp.com>,
        Fabio Estevam <festevam@gmail.com>,
        Shawn Guo <shawnguo@kernel.org>,
        Stefan Agner <stefan@agner.ch>,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        Linus Walleij <linus.walleij@linaro.org>,
        linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     Martin Kaiser <martin@kaiser.cx>
Subject: [PATCH] pinctrl: imx: make sure that maps are fully initialized
Date:   Sat, 10 Nov 2018 18:37:19 +0100
Message-Id: <1541871439-4882-1-git-send-email-martin@kaiser.cx>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

The commit that added scu based pinctrl support introduced a regression
for the mmio case. In the for-loop where the maps are initialized, we
end up creating a partially initialized map in some cases. This causes a
kernel panic when such a map is used at a later stage.

When scu is not used and and a pin uses the default pad configuration,
the current code sets the map's type and data.configs.group_or_pin but
no configs or num_configs are set. The previous code without scu
support did not create a new map at all in this case and did not
increment the counter.

Fix this by setting the map type and data.configs.group_or_pin only when
a configuration was set before, either by scu or by mmio using a
non-default pad config. Increment the counter only if a new map was
created.

Fixes: b96eea718bf6 ("pinctrl: fsl: add scu based pinctrl support")
Cc: A.s. Dong <aisheng.dong@nxp.com>
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
---

A crash looks like this

[    4.028525] Unable to handle kernel NULL pointer dereference at virtual address 00000000
[    4.036667] pgd = (ptrval)
[    4.039505] [00000000] *pgd=00000000
[    4.043162] Internal error: Oops: 5 [#1] ARM
[    4.047466] Modules linked in:
[    4.050582] CPU: 0 PID: 1 Comm: swapper Not tainted 4.20.0-rc1-next-20181106+ #2269
[    4.058270] Hardware name: Freescale i.MX25 (Device Tree Support)
[    4.064456] PC is at strcmp+0xc/0x40
[    4.068111] LR is at create_pinctrl+0x104/0x36c
[    4.072680] pc : [<c05699d8>]    lr : [<c0220bc8>]    psr: 60000013
[    4.078980] sp : d38bbce8  ip : d38bbcf8  fp : d38bbcf4
[    4.084236] r10: d3b2e0e0  r9 : d3b2e0c0  r8 : 00000000
[    4.089494] r7 : d3b2e238  r6 : d3b2e1c0  r5 : 00000000  r4 : d3b0df00
[    4.096054] r3 : 85981bcd  r2 : 85981bcd  r1 : d3a729e0  r0 : 00000000
[    4.102615] Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
[    4.109786] Control: 0005317f  Table: 80004000  DAC: 00000053
[    4.115569] Process swapper (pid: 1, stack limit = 0x(ptrval))
[    4.121437] Stack: (0xd38bbce8 to 0xd38bc000)
[    4.125849] bce0:                   d38bbd3c d38bbcf8 c0220bc8 c05699dc d38bbd3c c06adb58
[    4.134084] bd00: c078cc54 d3b0df0c d3a729e0 00000002 00000000 c078cc40 d3b0e800 d3b0e800
[    4.142318] bd20: c07c7ba0 c07e8ed0 c07c0480 c07cf820 d38bbd54 d38bbd40 c0220eec c0220ad4
[    4.150553] bd40: d3b0e800 d3b2e230 d38bbd74 d38bbd58 c0220f44 c0220e40 c028e24c d3b0e800
[    4.158787] bd60: 00000000 d3b0df50 d38bbd94 d38bbd78 c02a6e38 c0220f18 d3b0e948 d3b0e800
[    4.167019] bd80: 00000000 c07a66d8 d38bbdd4 d38bbd98 c028a614 c02a6dfc 20000013 85981bcd
[    4.175254] bda0: c07a66d8 00000000 d3b0e800 d3b0e800 c07a66d8 c07a66d8 c028acac c07c7ac8
[    4.183489] bdc0: c07c0480 c07cf820 d38bbe0c d38bbdd8 c028ac54 c028a4fc c03a8acc c03a69f0
[    4.191722] bde0: d38bbe0c d38bbdf0 d3b0e800 d3b0e834 c07a66d8 c028acac c07c7ac8 c07c0480
[    4.199954] be00: d38bbe2c d38bbe10 c028ad94 c028aaf0 00000000 d3b0e800 c075b028 c07a66d8
[    4.208189] be20: d38bbe5c d38bbe30 c028867c c028acbc d38bbe68 d38fe64c d3b08f30 85981bcd
[    4.216421] be40: c07a66d8 00000000 d3b29980 c0798384 d38bbe6c d38bbe60 c028a01c c0288618
[    4.224655] be60: d38bbe9c d38bbe70 c0289954 c028a004 c069a541 c07176a8 d38bbe9c c07a66d8
[    4.232890] be80: 00000006 c07176a8 c075b028 00000000 d38bbeb4 d38bbea0 c028b99c c028983c
[    4.241124] bea0: c075687c 00000006 d38bbec4 d38bbeb8 c02e9150 c028b8ec d38bbed4 d38bbec8
[    4.249357] bec0: c07176c8 c02e9108 d38bbf4c d38bbed8 c000ab54 c07176b8 c0034038 c06ed774
[    4.257589] bee0: 00000000 d38bbe00 d38bbee4 c06eb8ec 00000085 c06eb8ec 00000000 00000006
[    4.265822] bf00: 00000006 00000086 c06eae74 c06ed764 d38bbf34 d3ffcbbc d3ffcbc6 85981bcd
[    4.274057] bf20: 00000000 85981bcd c075687c 00000006 c07c0480 c0733830 00000086 c07cf820
[    4.282289] bf40: d38bbf94 d38bbf50 c06ee0e8 c000aadc 00000006 00000006 00000000 c06ed764
[    4.290520] bf60: 00000000 c0023240 d38bbf84 00000000 c0571424 00000000 00000000 00000000
[    4.298753] bf80: 00000000 00000000 d38bbfac d38bbf98 c057143c c06edf5c 60000053 00000000
[    4.306982] bfa0: 00000000 d38bbfb0 c00090e0 c0571434 00000000 00000000 00000000 00000000
[    4.315210] bfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[    4.323436] bfe0: 00000000 00000000 00000000 00000000 00000013 00000000 00000000 00000000
[    4.331634] Backtrace:
[    4.334199] [<c05699cc>] (strcmp) from [<c0220bc8>] (create_pinctrl+0x104/0x36c)
[    4.341679] [<c0220ac4>] (create_pinctrl) from [<c0220eec>] (pinctrl_get+0xbc/0xd8)
[    4.349403]  r10:c07cf820 r9:c07c0480 r8:c07e8ed0 r7:c07c7ba0 r6:d3b0e800 r5:d3b0e800
[    4.357265]  r4:c078cc40
[    4.359869] [<c0220e30>] (pinctrl_get) from [<c0220f44>] (devm_pinctrl_get+0x3c/0x7c)
[    4.367745]  r5:d3b2e230 r4:d3b0e800
[    4.371416] [<c0220f08>] (devm_pinctrl_get) from [<c02a6e38>] (pinctrl_bind_pins+0x4c/0x258)
[    4.379907]  r6:d3b0df50 r5:00000000 r4:d3b0e800 r3:c028e24c
[    4.385654] [<c02a6dec>] (pinctrl_bind_pins) from [<c028a614>] (really_probe+0x128/0x40c)
[    4.393883]  r6:c07a66d8 r5:00000000 r4:d3b0e800 r3:d3b0e948
[    4.399613] [<c028a4ec>] (really_probe) from [<c028ac54>] (driver_probe_device+0x174/0x1cc)
[    4.408031]  r10:c07cf820 r9:c07c0480 r8:c07c7ac8 r7:c028acac r6:c07a66d8 r5:c07a66d8
[    4.415893]  r4:d3b0e800
[    4.418497] [<c028aae0>] (driver_probe_device) from [<c028ad94>] (__driver_attach+0xe8/0x138)
[    4.427084]  r9:c07c0480 r8:c07c7ac8 r7:c028acac r6:c07a66d8 r5:d3b0e834 r4:d3b0e800


I'm not sure what exactly is required to trigger the problem. I saw the crash
for a dt device node like this where pinctrl links to two nodes with the actual pin
settings.

&spi1 {
    pinctrl-names = "default";
    pinctrl-0 = <&pinctrl_spi1_common &pinctrl_spi1_cs>;
}

pinctrl_spi1_common contains a couple of pins with non-default pad settings and
pinctrl_spi1_cs contains a single pin that uses the default pad configuration.

pinctrl_spi1_cs: spi1_cs_grp {
   fsl,pins = <
      MX25_PAD_CSPI1_SS0__GPIO_1_16  0x80000000
   >;
};


 drivers/pinctrl/freescale/pinctrl-imx.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/pinctrl/freescale/pinctrl-imx.c b/drivers/pinctrl/freescale/pinctrl-imx.c
index 78d33dfb4d2d..0c4ad8d19226 100644
--- a/drivers/pinctrl/freescale/pinctrl-imx.c
+++ b/drivers/pinctrl/freescale/pinctrl-imx.c
@@ -108,9 +108,6 @@ static int imx_dt_node_to_map(struct pinctrl_dev *pctldev,
 	new_map++;
 	for (i = j = 0; i < grp->num_pins; i++) {
 		pin = &((struct imx_pin *)(grp->data))[i];
-		new_map[j].type = PIN_MAP_TYPE_CONFIGS_PIN;
-		new_map[j].data.configs.group_or_pin =
-					pin_get_name(pctldev, pin->pin);
 
 		if (info->flags & IMX_USE_SCU) {
 			/*
@@ -126,7 +123,12 @@ static int imx_dt_node_to_map(struct pinctrl_dev *pctldev,
 			new_map[j].data.configs.num_configs = 1;
 		}
 
-		j++;
+		if (new_map[j].data.configs.num_configs) {
+			new_map[j].type = PIN_MAP_TYPE_CONFIGS_PIN;
+			new_map[j].data.configs.group_or_pin =
+				pin_get_name(pctldev, pin->pin);
+			j++;
+		}
 	}
 
 	dev_dbg(pctldev->dev, "maps: function %s group %s num %d\n",
-- 
2.1.4