PROCESSOR-SDK-AM437X: Disable wake-up from UART0

Hello,

I am currently returning to office and will get back to you as soon as possible. Please ping this thread by Thursday if you haven't received a response.

Thanks,

Anshu

Hello,

I'm not very familiar with this SDK version since this is an older Linux Kernel. Can you try the following:

@@ -587,15 +587,6 @@ AM4372_IOPAD(0x974, PIN_INPUT | PULL_DISABLE | SLEWCTRL_FAST | DS0_PULL_UP_DOWN_
                >;
        };
 
-       uart0_pins_sleep: uart0-sleep-pins {
-               pinctrl-single,pins = <
-                       AM4372_IOPAD(0x968, DS0_PULL_UP_DOWN_EN | INPUT_EN | MUX_MODE7) /* uart0_ctsn.uart0_ctsn */
-                       AM4372_IOPAD(0x96C, DS0_PULL_UP_DOWN_EN | INPUT_EN | MUX_MODE7) /* uart0_rtsn.uart0_rtsn */
-                       AM4372_IOPAD(0x970, PIN_INPUT_PULLUP | SLEWCTRL_FAST | DS0_PULL_UP_DOWN_EN | MUX_MODE0) /* uart0_rxd.uart0_rxd */
-                       AM4372_IOPAD(0x974, PIN_INPUT_PULLDOWN | SLEWCTRL_FAST | DS0_PULL_UP_DOWN_EN | MUX_MODE0) /* uart0_txd.uart0_txd */
-               >;
-       };
-
        matrix_keypad_default: matrix-keypad-default-pins {
                pinctrl-single,pins = <
                        AM4372_IOPAD(0x9a4, PIN_OUTPUT | MUX_MODE7)
@@ -617,9 +608,8 @@ AM4372_IOPAD(0x954, PIN_INPUT_PULLDOWN | MUX_MODE0)
 
 &uart0 {
        status = "okay";
-       pinctrl-names = "default", "sleep";
+       pinctrl-names = "default";
        pinctrl-0 = <&uart0_pins_default>;
-       pinctrl-1 = <&uart0_pins_sleep>;
 };

 This is modifying the AM437x EVM device tree: https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/tree/arch/arm/boot/dts/am437x-gp-evm.dts?h=ti-linux-4.19.y

Best Regards,
Anshu

Hi,

Thank you for providing your solution.

We could not solve our problem even if we applied your solution.
UART0 is still used as wake sources.

When we type any key on UART0 console, suspend mode is exited.
-------------------------------------------------------

root@am437x-evm:~# echo mem > /sys/power/state
[ 54.160445] PM: suspend entry (deep)
[ 54.164054] PM: Syncing filesystems ... done.
[ 54.200131] Freezing user space processes ... (elapsed 0.001 seconds) done.
[ 54.209135] OOM killer disabled.
[ 54.212507] Freezing remaining freezable tasks ... (elapsed 0.001 seconds) done.
[ 54.221339] Suspending console(s) (use no_console_suspend to debug)
[ 54.767146] cpsw 4a100000.ethernet eth0: Link is Down
[ 54.779241] pm33xx pm33xx: PM: Successfully put all powerdomains to target state
[ 54.779241] PM: Wakeup source UART
[ 54.805183] net eth0: initializing cpsw version 1.15 (0)
[ 54.904364] Micrel KSZ9031 Gigabit PHY 4a101000.mdio:00: attached PHY driver [Micrel KSZ9031 Gigabit PHY] (mii_bus:phy_addr=4a101000.mdio:00, irq=POLL)
[ 54.941039] usb usb1: root hub lost power or was reset
[ 54.941060] usb usb2: root hub lost power or was reset
[ 54.945021] usb usb3: root hub lost power or was reset
[ 54.945044] usb usb4: root hub lost power or was reset
[ 55.120344] OOM killer enabled.
[ 55.123507] Restarting tasks ... done.
[ 55.182911] PM: suspend exit

-------------------------------------------------------

Could you please provide another solution?

Thank you.

Hi,

Thank you for providing the solution.

I have a question about the patch to enable/disable UART wakeup.
It seems that we can control UART wakeup capability via sysf.
I don't know why UART0 wakeup is enabled even if "/sys/class/tty/ttyS0/device/power/wakeup" value is already "disabled" in our board.

Could you please let us know this reason?

Thank you.

Hello,

I'm not sure the reason. I will file a bug on this issue, but this was likely fixed in newer Linux SDK versions.

Thanks,

Anshu

Hi,

Thank you for your reply.

We understood that we cannot control UART wakeup capability via sysf.
So, we changed as below to disable UART wakeup capability.
Please check it and give us feedback.

--- a/drivers/tty/serial/8250/8250_omap.c
+++ b/drivers/tty/serial/8250/8250_omap.c
@@ -1336,6 +1336,7 @@ static int omap8250_probe(struct platform_device *pdev)
 	spin_lock_init(&priv->rx_dma_lock);
 
 	device_init_wakeup(&pdev->dev, true);
+	device_set_wakeup_capable(&pdev->dev, false);
 	pm_runtime_use_autosuspend(&pdev->dev);
 	pm_runtime_set_autosuspend_delay(&pdev->dev, -1);

Thank you.

Hello,

We cannot provide assistance with changing or customizing drivers on the E2E Forums.

Best Regards,

Anshu