--- zzzz-none-000/linux-4.4.271/drivers/firmware/psci.c	2021-06-03 06:22:09.000000000 +0000
+++ hawkeye-5590-750/linux-4.4.271/drivers/firmware/psci.c	2023-04-19 10:22:28.000000000 +0000
@@ -13,6 +13,7 @@
 
 #define pr_fmt(fmt) "psci: " fmt
 
+#include <linux/delay.h>
 #include <linux/arm-smccc.h>
 #include <linux/errno.h>
 #include <linux/linkage.h>
@@ -249,6 +250,31 @@
 
 static void psci_sys_reset(enum reboot_mode reboot_mode, const char *cmd)
 {
+	/*
+	 * From kernel, psci_sys_reset function is called during reboot for
+	 * both warm and cold reset.
+	 *
+	 * QSEE differentiates between warm and cold reset by checking the
+	 * TZ_WONCE register, which is set by SBL based on CDT settings.
+	 *
+	 * During cold reset, QSEE communicates with RPM via glink and requests
+	 * RPM to reset and during warm reset, QSEE directly toggles PSHOLD
+	 * register.
+	 *
+	 * During warm reset case, the "Restarting system" print after reboot
+	 * command is given is not flushed from the serial driver to console
+	 * before which the board gets rebooted.
+	 *
+	 * The pr_emerg("Restarting system\n") is called after the reboot
+	 * notifier callbacks are finished, therefore even if we add a
+	 * reboot notifier in serial driver and flush the tx buffer, it still
+	 * wouldn't help.
+	 *
+	 * We have added this 100 ms delay before invoking psci call for the
+	 * serial driver to flush the tx buf contents to console before
+	 * rebooting.
+	 */
+	mdelay(100);
 	invoke_psci_fn(PSCI_0_2_FN_SYSTEM_RESET, 0, 0, 0);
 }
 
@@ -503,7 +529,7 @@
 
 	np = of_find_matching_node_and_match(NULL, psci_of_match, &matched_np);
 
-	if (!np)
+	if (!np || !of_device_is_available(np))
 		return -ENODEV;
 
 	init_fn = (psci_initcall_t)matched_np->data;