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From:   Mikhail Rudenko <mike.rudenko@gmail.com>
To:     Kishon Vijay Abraham I <kishon@ti.com>,
        Vinod Koul <vkoul@kernel.org>,
        Heiko Stuebner <heiko@sntech.de>,
        Peter Geis <pgwipeout@gmail.com>,
        Samuel Holland <samuel@sholland.org>
Cc:     Mikhail Rudenko <mike.rudenko@gmail.com>, stable@vger.kernel.org,
        linux-phy@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org,
        linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: [PATCH] phy: rockchip-inno-usb2: Fix otg port initialization
Date:   Sat, 17 Sep 2022 19:58:20 +0300
Message-Id: <20220917165820.2304306-1-mike.rudenko@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

There are two issues in rockchip_usb2phy_otg_port_init(): (1) even if
devm_extcon_register_notifier() returns error, the code proceeds to
the next if statement and (2) if no extcon is defined in of_node, the
return value of property_enabled() is reused as the return value of
the whole function. If the return value of property_enable() is
nonzero, (2) results in an unexpected probe failure and kernel panic
in delayed work:

    Unable to handle kernel NULL pointer dereference at virtual address 00000000
    Mem abort info:
      ESR = 0x0000000086000006
      EC = 0x21: IABT (current EL), IL = 32 bits
      SET = 0, FnV = 0
      EA = 0, S1PTW = 0
      FSC = 0x06: level 2 translation fault
    user pgtable: 4k pages, 48-bit VAs, pgdp=00000000019dc000
    [0000000000000000] pgd=080000000131a003, p4d=080000000131a003, pud=080000000
    Internal error: Oops: 86000006 [#1] PREEMPT SMP
    Modules linked in: ipv6
    CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.0.0-rc5 #114
    Hardware name: FriendlyElec NanoPi M4 (DT)
    pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
    pc : 0x0
    lr : call_timer_fn.constprop.0+0x24/0x80
    sp : ffff80000a40ba40
    x29: ffff80000a40ba40 x28: 0000000000000000 x27: ffff80000a40baf0
    x26: ffff800009e779c0 x25: ffff00007fb28070 x24: ffff00007fb28028
    x23: ffff80000a40baf0 x22: 0000000000000000 x21: 0000000000000101
    x20: ffff0000006ad880 x19: 0000000000000000 x18: 0000000000000006
    x17: ffff8000761af000 x16: ffff80000800c000 x15: 0000000000004000
    x14: ffff0000006ad880 x13: 000000000000030a x12: 0000000000000000
    x11: ffff8000761af000 x10: ffff80000800bf40 x9 : ffff00007fb2d038
    x8 : 0000000000000001 x7 : 0000000000000009 x6 : 0000000000000240
    x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000200
    x2 : 000000003fffffff x1 : 0000000000000000 x0 : ffff0000016c9710
    Call trace:
     0x0
     __run_timers+0x220/0x264
     run_timer_softirq+0x20/0x40
     __do_softirq+0x10c/0x298
     __irq_exit_rcu+0xec/0xf4
     irq_exit_rcu+0x10/0x1c
     el1_interrupt+0x38/0x70
     el1h_64_irq_handler+0x18/0x24
     el1h_64_irq+0x64/0x68
     cpuidle_enter_state+0x130/0x2fc
     cpuidle_enter+0x38/0x50
     do_idle+0x22c/0x2c0
     cpu_startup_entry+0x24/0x30
     secondary_start_kernel+0x130/0x14c
     __secondary_switched+0xb0/0xb4
    Code: bad PC value
    ---[ end trace 0000000000000000 ]---
    Kernel panic - not syncing: Oops: Fatal exception in interrupt
    SMP: stopping secondary CPUs
    Kernel Offset: disabled
    CPU features: 0x4000,0820b021,00001086
    Memory Limit: none
    ---[ end Kernel panic - not syncing: Oops: Fatal exception in interrupt ]---

Refactor the control flow to avoid both issues. Since the code below
out: label does no cleanup, return error codes immediately instead of
using gotos and return success at the end of the function.

Cc: stable@vger.kernel.org
Fixes: 8dc60f8da22f ("phy: rockchip-inno-usb2: Sync initial otg state")
Signed-off-by: Mikhail Rudenko <mike.rudenko@gmail.com>
---
 drivers/phy/rockchip/phy-rockchip-inno-usb2.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/phy/rockchip/phy-rockchip-inno-usb2.c b/drivers/phy/rockchip/phy-rockchip-inno-usb2.c
index 0b1e9337ee8e..d31b35d55927 100644
--- a/drivers/phy/rockchip/phy-rockchip-inno-usb2.c
+++ b/drivers/phy/rockchip/phy-rockchip-inno-usb2.c
@@ -1144,8 +1144,7 @@ static int rockchip_usb2phy_otg_port_init(struct rockchip_usb2phy *rphy,
 	rport->mode = of_usb_get_dr_mode_by_phy(child_np, -1);
 	if (rport->mode == USB_DR_MODE_HOST ||
 	    rport->mode == USB_DR_MODE_UNKNOWN) {
-		ret = 0;
-		goto out;
+		return 0;
 	}
 
 	INIT_DELAYED_WORK(&rport->chg_work, rockchip_chg_detect_work);
@@ -1154,7 +1153,7 @@ static int rockchip_usb2phy_otg_port_init(struct rockchip_usb2phy *rphy,
 	ret = rockchip_usb2phy_port_irq_init(rphy, rport, child_np);
 	if (ret) {
 		dev_err(rphy->dev, "failed to init irq for host port\n");
-		goto out;
+		return ret;
 	}
 
 	if (!IS_ERR(rphy->edev)) {
@@ -1162,8 +1161,10 @@ static int rockchip_usb2phy_otg_port_init(struct rockchip_usb2phy *rphy,
 
 		ret = devm_extcon_register_notifier(rphy->dev, rphy->edev,
 					EXTCON_USB_HOST, &rport->event_nb);
-		if (ret)
+		if (ret) {
 			dev_err(rphy->dev, "register USB HOST notifier failed\n");
+			return ret;
+		}
 
 		if (!of_property_read_bool(rphy->dev->of_node, "extcon")) {
 			/* do initial sync of usb state */
@@ -1172,8 +1173,7 @@ static int rockchip_usb2phy_otg_port_init(struct rockchip_usb2phy *rphy,
 		}
 	}
 
-out:
-	return ret;
+	return 0;
 }
 
 static int rockchip_usb2phy_probe(struct platform_device *pdev)
-- 
2.37.3