linux-kernel - [tip: sched/core] arm, OMAP2: Use WFI for omap2_pm

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Date:   Fri, 13 Jan 2023 12:31:07 -0000
From:   "tip-bot2 for Peter Zijlstra" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Tony Lindgren <tony@...mide.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Frederic Weisbecker <frederic@...nel.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: sched/core] arm, OMAP2: Use WFI for omap2_pm_idle()

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     259c95afac6f2758760f158537e1d28358b4639c
Gitweb:        https://git.kernel.org/tip/259c95afac6f2758760f158537e1d28358b4639c
Author:        Peter Zijlstra <peterz@...radead.org>
AuthorDate:    Thu, 12 Jan 2023 20:43:53 +01:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Fri, 13 Jan 2023 11:48:17 +01:00

arm, OMAP2: Use WFI for omap2_pm_idle()

arch_cpu_idle() is a very simple idle interface and exposes only a
single idle state and is expected to not require RCU and not do any
tracing/instrumentation.

As such, omap2_pm_idle() is not a valid implementation. Replace it
with a simple (shallow) omap2_do_wfi() call.

Omap2 doesn't have a cpuidle driver; but adding one would be the
recourse to (re)gain the other idle states.

Suggested-by: Tony Lindgren <tony@...mide.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Tested-by: Tony Lindgren <tony@...mide.com>
Tested-by: Ulf Hansson <ulf.hansson@...aro.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Acked-by: Frederic Weisbecker <frederic@...nel.org>
Link: https://lore.kernel.org/r/20230112195541.721697850@infradead.org
---
 arch/arm/mach-omap2/pm24xx.c | 51 +----------------------------------
 1 file changed, 2 insertions(+), 49 deletions(-)

diff --git a/arch/arm/mach-omap2/pm24xx.c b/arch/arm/mach-omap2/pm24xx.c
index 6953c47..d52cf73 100644
--- a/arch/arm/mach-omap2/pm24xx.c
+++ b/arch/arm/mach-omap2/pm24xx.c
@@ -116,50 +116,12 @@ no_sleep:
 
 static int sti_console_enabled;
 
-static int omap2_allow_mpu_retention(void)
-{
-	if (!omap2xxx_cm_mpu_retention_allowed())
-		return 0;
-	if (sti_console_enabled)
-		return 0;
-
-	return 1;
-}
-
-static void omap2_enter_mpu_retention(void)
+static void omap2_do_wfi(void)
 {
 	const int zero = 0;
 
-	/* The peripherals seem not to be able to wake up the MPU when
-	 * it is in retention mode. */
-	if (omap2_allow_mpu_retention()) {
-		/* REVISIT: These write to reserved bits? */
-		omap_prm_clear_mod_irqs(CORE_MOD, PM_WKST1, ~0);
-		omap_prm_clear_mod_irqs(CORE_MOD, OMAP24XX_PM_WKST2, ~0);
-		omap_prm_clear_mod_irqs(WKUP_MOD, PM_WKST, ~0);
-
-		/* Try to enter MPU retention */
-		pwrdm_set_next_pwrst(mpu_pwrdm, PWRDM_POWER_RET);
-
-	} else {
-		/* Block MPU retention */
-		pwrdm_set_next_pwrst(mpu_pwrdm, PWRDM_POWER_ON);
-	}
-
 	/* WFI */
 	asm("mcr p15, 0, %0, c7, c0, 4" : : "r" (zero) : "memory", "cc");
-
-	pwrdm_set_next_pwrst(mpu_pwrdm, PWRDM_POWER_ON);
-}
-
-static int omap2_can_sleep(void)
-{
-	if (omap2xxx_cm_fclks_active())
-		return 0;
-	if (__clk_is_enabled(osc_ck))
-		return 0;
-
-	return 1;
 }
 
 static void omap2_pm_idle(void)
@@ -169,16 +131,7 @@ static void omap2_pm_idle(void)
 	if (omap_irq_pending())
 		return;
 
-	error = cpu_cluster_pm_enter();
-	if (error || !omap2_can_sleep()) {
-		omap2_enter_mpu_retention();
-		goto out_cpu_cluster_pm;
-	}
-
-	omap2_enter_full_retention();
-
-out_cpu_cluster_pm:
-	cpu_cluster_pm_exit();
+	omap2_do_wfi();
 }
 
 static void __init prcm_setup_regs(void)