linux-kernel - [PATCH v4 04/11] i2c: riic: Enable runtime PM autosuspend support

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Message-Id: <20240819102348.1592171-5-claudiu.beznea.uj@bp.renesas.com>
Date: Mon, 19 Aug 2024 13:23:41 +0300
From: Claudiu <claudiu.beznea@...on.dev>
To: chris.brandt@...esas.com,
	andi.shyti@...nel.org,
	robh@...nel.org,
	krzk+dt@...nel.org,
	conor+dt@...nel.org,
	geert+renesas@...der.be,
	magnus.damm@...il.com,
	p.zabel@...gutronix.de,
	wsa+renesas@...g-engineering.com
Cc: linux-renesas-soc@...r.kernel.org,
	linux-i2c@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	claudiu.beznea@...on.dev,
	Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Subject: [PATCH v4 04/11] i2c: riic: Enable runtime PM autosuspend support

From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>

Enable runtime PM autosuspend support for the RIIC driver. With this, in
case there are consecutive xfer requests the device wouldn't be runtime
enabled/disabled after each consecutive xfer but after the
the delay configured by user. With this, we can avoid touching hardware
registers involved in runtime PM suspend/resume saving in this way some
cycles. The default chosen autosuspend delay is zero to keep the
previous driver behavior.

Reviewed-by: Wolfram Sang <wsa+renesas@...g-engineering.com>
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
---

Changes in v4:
- collected tags
- added a comment on top of pm_runtime_set_autosuspend_delay()

Changes in v3:
- none

Changes in v2:
- none

 drivers/i2c/busses/i2c-riic.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-riic.c b/drivers/i2c/busses/i2c-riic.c
index 6fc41bde2ec2..ec854a525a0b 100644
--- a/drivers/i2c/busses/i2c-riic.c
+++ b/drivers/i2c/busses/i2c-riic.c
@@ -171,7 +171,8 @@ static int riic_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
 	}
 
  out:
-	pm_runtime_put(dev);
+	pm_runtime_mark_last_busy(dev);
+	pm_runtime_put_autosuspend(dev);
 
 	return riic->err ?: num;
 }
@@ -399,7 +400,8 @@ static int riic_init_hw(struct riic_dev *riic, struct i2c_timings *t)
 
 	riic_clear_set_bit(riic, ICCR1_IICRST, 0, RIIC_ICCR1);
 
-	pm_runtime_put(dev);
+	pm_runtime_mark_last_busy(dev);
+	pm_runtime_put_autosuspend(dev);
 	return 0;
 }
 
@@ -479,6 +481,9 @@ static int riic_i2c_probe(struct platform_device *pdev)
 
 	i2c_parse_fw_timings(dev, &i2c_t, true);
 
+	/* Default 0 to save power. Can be overridden via sysfs for lower latency. */
+	pm_runtime_set_autosuspend_delay(dev, 0);
+	pm_runtime_use_autosuspend(dev);
 	pm_runtime_enable(dev);
 
 	ret = riic_init_hw(riic, &i2c_t);
@@ -496,6 +501,7 @@ static int riic_i2c_probe(struct platform_device *pdev)
 
 out:
 	pm_runtime_disable(dev);
+	pm_runtime_dont_use_autosuspend(dev);
 	return ret;
 }
 
@@ -512,6 +518,7 @@ static void riic_i2c_remove(struct platform_device *pdev)
 	}
 	i2c_del_adapter(&riic->adapter);
 	pm_runtime_disable(dev);
+	pm_runtime_dont_use_autosuspend(dev);
 }
 
 static const struct riic_of_data riic_rz_a_info = {
-- 
2.39.2