Re: [PATCH v2 2/4] ARM: mvebu: Add standby support

[Thomas Petazzoni <thomas.petazzoni@free-electrons.com>]

Dear Gregory CLEMENT,

On Tue, 30 Jun 2015 19:18:58 +0200, Gregory CLEMENT wrote:
> Until now only one Armada XP and one Armada 388 based board supported
> suspend to ram. However, most of the recent mvebu SoCs can support the
> standby mode. Unlike for the suspend to ram, nothing special have to

have -> has

> be done for these SoCs. This patch allows the system to use the
> standby mode on Armada 370, 38x, 39x and XP SoCs. There are issues
> with the Armada 375, and the support would be added (if possible) in a

would -> might

> future patch.
> 
> Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
> ---
>  arch/arm/mach-mvebu/common.h   |  5 ++--
>  arch/arm/mach-mvebu/pm-board.c | 17 ++++++++-----
>  arch/arm/mach-mvebu/pm.c       | 57 ++++++++++++++++++++++++++++++++++++------
>  3 files changed, 64 insertions(+), 15 deletions(-)

On the implementation side, this is much more complicated that it needs
to be I believe. You don't need this mechanism to register the
board-specific hook. Just make pm.c register the suspend_ops in a
late_initcall(), and the pm-board.c register the board specific hook in
a late_initcall(), and have pm.c say that it supports suspend to RAM
only if the board-specific hook has been registered.

Something like the below (only compile tested, not runtime tested) :

commit 0b74c5b2916cb4be216bd2c607faf5c10a482284
Author: Gregory CLEMENT <gregory.clement@free-electrons.com>
Date:   Tue Jun 30 19:18:58 2015 +0200

    ARM: mvebu: Add standby support
    
    Until now only one Armada XP and one Armada 388 based board supported
    suspend to ram. However, most of the recent mvebu SoCs can support the
    standby mode. Unlike for the suspend to ram, nothing special have to
    be done for these SoCs. This patch allows the system to use the
    standby mode on Armada 370, 38x, 39x and XP SoCs. There are issues
    with the Armada 375, and the support would be added (if possible) in a
    future patch.
    
    Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>

diff --git a/arch/arm/mach-mvebu/common.h b/arch/arm/mach-mvebu/common.h
index 3e0aca1..6b77549 100644
--- a/arch/arm/mach-mvebu/common.h
+++ b/arch/arm/mach-mvebu/common.h
@@ -25,6 +25,6 @@ int mvebu_system_controller_get_soc_id(u32 *dev, u32 *rev);
 
 void __iomem *mvebu_get_scu_base(void);
 
-int mvebu_pm_init(void (*board_pm_enter)(void __iomem *sdram_reg, u32 srcmd));
-
+int mvebu_pm_suspend_init(void (*board_pm_enter)(void __iomem *sdram_reg,
+							u32 srcmd));
 #endif
diff --git a/arch/arm/mach-mvebu/pm-board.c b/arch/arm/mach-mvebu/pm-board.c
index acc69e3..4dccc64 100644
--- a/arch/arm/mach-mvebu/pm-board.c
+++ b/arch/arm/mach-mvebu/pm-board.c
@@ -135,7 +135,7 @@ static int __init mvebu_armada_pm_init(void)
 	if (!gpio_ctrl)
 		return -ENOMEM;
 
-	mvebu_pm_init(mvebu_armada_pm_enter);
+	mvebu_pm_suspend_init(mvebu_armada_pm_enter);
 
 out:
 	of_node_put(np);
diff --git a/arch/arm/mach-mvebu/pm.c b/arch/arm/mach-mvebu/pm.c
index f249c8e..db31cbb 100644
--- a/arch/arm/mach-mvebu/pm.c
+++ b/arch/arm/mach-mvebu/pm.c
@@ -204,13 +204,10 @@ static int mvebu_pm_store_bootinfo(void)
 	return 0;
 }
 
-static int mvebu_pm_enter(suspend_state_t state)
+static int mvebu_enter_suspend(void)
 {
 	int ret;
 
-	if (state != PM_SUSPEND_MEM)
-		return -EINVAL;
-
 	ret = mvebu_pm_store_bootinfo();
 	if (ret)
 		return ret;
@@ -226,16 +223,57 @@ static int mvebu_pm_enter(suspend_state_t state)
 	set_cpu_coherent();
 
 	cpu_pm_exit();
+	return 0;
+}
+
+static int mvebu_pm_enter(suspend_state_t state)
+{
+	switch (state) {
+	case PM_SUSPEND_STANDBY:
+		cpu_do_idle();
+		break;
+	case PM_SUSPEND_MEM:
+		return mvebu_enter_suspend();
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static int mvebu_pm_valid(suspend_state_t state)
+{
+	if (state == PM_SUSPEND_STANDBY)
+		return 1;
+
+	if (state == PM_SUSPEND_MEM && mvebu_board_pm_enter != NULL)
+		return 1;
 
 	return 0;
 }
 
 static const struct platform_suspend_ops mvebu_pm_ops = {
 	.enter = mvebu_pm_enter,
-	.valid = suspend_valid_only_mem,
+	.valid = mvebu_pm_valid,
 };
 
-int __init mvebu_pm_init(void (*board_pm_enter)(void __iomem *sdram_reg, u32 srcmd))
+static int __init mvebu_pm_init(void)
+{
+	if (!of_machine_is_compatible("marvell,armadaxp") &&
+	    !of_machine_is_compatible("marvell,armada370") &&
+	    !of_machine_is_compatible("marvell,armada380") &&
+	    !of_machine_is_compatible("marvell,armada390"))
+		return -ENODEV;
+
+	suspend_set_ops(&mvebu_pm_ops);
+
+	return 0;
+}
+
+
+late_initcall(mvebu_pm_init);
+
+int __init mvebu_pm_suspend_init(void (*board_pm_enter)(void __iomem *sdram_reg,
+							u32 srcmd))
 {
 	struct device_node *np;
 	struct resource res;
@@ -267,7 +305,5 @@ int __init mvebu_pm_init(void (*board_pm_enter)(void __iomem *sdram_reg, u32 src
 
 	mvebu_board_pm_enter = board_pm_enter;
 
-	suspend_set_ops(&mvebu_pm_ops);
-
 	return 0;
 }

-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com