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X-OriginatorOrg: ti.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 08 Jan 2026 18:03:48.1293 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 758d7ca2-db51-4e07-da5e-08de4ee045b4 X-MS-Exchange-CrossTenant-Id: e5b49634-450b-4709-8abb-1e2b19b982b7 X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=e5b49634-450b-4709-8abb-1e2b19b982b7;Ip=[198.47.23.194];Helo=[lewvzet200.ext.ti.com] X-MS-Exchange-CrossTenant-AuthSource: CO1PEPF000075F2.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR10MB4124 On 11:52-20260108, Kendall Willis wrote: > On 1/8/26 11:05, Bryan Brattlof wrote: > > On January 7, 2026 thus sayeth Kendall Willis: > > > On 1/7/26 10:45, Bryan Brattlof wrote: > > > > On January 6, 2026 thus sayeth Kendall Willis: > > > > > K3 TI AM62L SoC supports wakeup from WKUP UART when the SoC is in the > > > > > DeepSleep low power mode. To allow wakeup from WKUP UART the target-module > > > > > device tree node is enabled. The ti-sysc interconnect target module driver > > > > > is used to configure the the SYSCONFIG related registers. In this case, > > > > > the interconnect target module node configures the WKUP UART to be able to > > > > > wakeup from system suspend. The SYSC register is used to enable wakeup > > > > > from system suspend for the WKUP UART. Refer to 14.7.2.5 UART in the > > > > > AM62L Techincal Reference Manual for registers referenced [1]. > > > > > > > > > > Previous TI SoCs configure the WKUP UART to wakeup from system suspend > > > > > using the ti-sysc interconnect target module driver. Refer to commit > > > > > ce27f7f9e328 ("arm64: dts: ti: k3-am62-wakeup: Configure ti-sysc for > > > > > wkup_uart0") for an example of this. > > > > > > > > I think I may be confused. What is setting the pinmux for the wkup_uart > > > > to allow us to trigger the wake event? It looks like they reset to GPIO > > > > pins if not set. Is firmware doing this? > > > > > > On AM62L, the WKUP UART pinmux is initially set by TFA so that it is set to > > > the UART pins, not GPIO. The target-module node sets the WKUP UART SYSC > > > register so that wakeup is enabled. > > > > > > > Nice however should we mark the UART in the board file as reserved for > > TFA or is it free to be used by Linux and only during the low power > > modes after Linux is asleep will it be used by TFA? > > > > ~Bryan > > Sorry for the confusion, I said earlier that the WKUP UART could be used by > firmware, but that is not to say it is specifically reserved by the firmware > in general. TFA sets the WKUP UART pins, but it does not use the WKUP UART > for anything else. The only exception for TFA using the WKUP UART is if the > user chooses to use the WKUP UART for TFA debugging [1]. > > All of this to say that the WKUP UART *can* be used by Linux, it does not > need to be reserved for firmware. > If you are going to use it for linux wakeup, then why dont we enable it for linux? what TFA does or not should not dictate device tree unless it is a hardware description - provide the full description in dt. -- Regards, Nishanth Menon Key (0xDDB5849D1736249D) / Fingerprint: F8A2 8693 54EB 8232 17A3 1A34 DDB5 849D 1736 249D https://ti.com/opensource