[devel] [PATCH 21/35] pm: disable all sleep states on Baikal-M based boards

[asheplyakov@yandex.ru]

From: Alexey Sheplyakov <asheplyakov@altlinux.org>

These days desktop environments try to put computer into a sleep
state after a certain period of inactivity. TF307 board is able
to enter a sleep state, however it does *NOT* wakeup via power
button or keyboard/mouse.

Apparently the only wakeup sources on TF307 board are

- Real time clock (RTC)
- Ethernet

Surprisingly BMC (board management controller) is NOT a wakeup
source. Also tp_bmc driver does not use interrupts, and polls
the device instead. Perhaps BMC is unable to generate interrupts
at all?

To avoid the problem disable all sleep states (including s2idle)
on Baikal-M systems

X-DONTUPSTREAM
X-feature-Baikal-M
---
 kernel/power/suspend.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
index 6fcdee7e87a5..99298e393d48 100644
--- a/kernel/power/suspend.c
+++ b/kernel/power/suspend.c
@@ -30,6 +30,7 @@
 #include <trace/events/power.h>
 #include <linux/compiler.h>
 #include <linux/moduleparam.h>
+#include <linux/of.h>
 
 #include "power.h"
 
@@ -236,6 +237,17 @@ EXPORT_SYMBOL_GPL(suspend_valid_only_mem);
 
 static bool sleep_state_supported(suspend_state_t state)
 {
+#ifdef CONFIG_OF
+	if (of_device_is_compatible(of_root, "baikal,baikal-m")) {
+		/* XXX: there are no wakeup sources except RTC and Ethernet
+		 * on BE-M1000 based boards. In other words, no way to wakeup
+		 * system via the keyboard or power button.
+		 * Thus even s2idle is unusable on BE-M1000 systems.
+		 */
+		pr_info("%s: no useful wakeup sources on Baikal-M", __func__);
+		return false;
+	}
+#endif
 	return state == PM_SUSPEND_TO_IDLE || valid_state(state);
 }
 
-- 
2.32.0