Some K3 CPSW NUSS instances can lose context after PM runtime ON->OFF->ON
transition depending on integration (including all submodules: CPTS, MDIO,
etc), like J721E Main CPSW (CPSW9G).

In case CPTS is enabled it's initialized during probe and does not expect
to be reset. Hence, keep K3 CPSW active by forbidding PM runtime if CPTS is
enabled.

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Reviewed-by: Jesse Brandeburg <redacted>
---
 drivers/net/ethernet/ti/am65-cpsw-nuss.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/net/ethernet/ti/am65-cpsw-nuss.c b/drivers/net/ethernet/ti/am65-cpsw-nuss.c
index fecaf6b8270f..0bc0eec46709 100644
--- a/drivers/net/ethernet/ti/am65-cpsw-nuss.c
+++ b/drivers/net/ethernet/ti/am65-cpsw-nuss.c

@@ -1727,6 +1727,13 @@ static int am65_cpsw_init_cpts(struct am65_cpsw_common *common)
 		return ret;
 	}
 	common->cpts = cpts;
+	/* Forbid PM runtime if CPTS is running.
+	 * K3 CPSWxG modules may completely lose context during ON->OFF
+	 * transitions depending on integration.
+	 * AM65x/J721E MCU CPSW2G: false
+	 * J721E MAIN_CPSW9G: true
+	 */
+	pm_runtime_forbid(dev);
 
 	return 0;
 }

-- 
2.17.1