linux-kernel - [PATCH v5] i2c: designware: Currently if the SoC needs pinctrl to switch the SCL and SDA from the I2C function to GPI

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Date:   Tue, 22 Aug 2023 16:25:13 +0200
From:   Yann Sionneau <ysionneau@...ray.eu>
To:     Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Julian Vetter <jvetter@...rayinc.com>
Cc:     linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
        Yann Sionneau <ysionneau@...ray.eu>
Subject: [PATCH v5] i2c: designware: Currently if the SoC needs pinctrl to switch the SCL and SDA from the I2C function to GPI

scl-gpio = <>;
sda-gpio = <>;

Are not enough for some SoCs to have a working recovery.
Some need:

scl-gpio = <>;
sda-gpio = <>;
pinctrl-names = "default", "recovery";
pinctrl-0 = <&i2c_pins_hw>;
pinctrl-1 = <&i2c_pins_gpio>;

The driver was not filling rinfo->pinctrl with the device node
pinctrl data which is needed by generic recovery code.

Signed-off-by: Yann Sionneau <ysionneau@...ray.eu>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
---
V4 -> V5:
* put back `else if`
* reword the commit msg Subject to add the `i2c: designware: ` tag
* Add the missing `Reviewed-by: Andy Shevchenko` tag

V3 -> V4:
* Replace `else if` by simply `if`.

V2 -> V3:
* put back 'if (!rinfo->pinctrl)' test since devm_pinctrl_get()
can return NULL if CONFIG_PINCTRL is not set.
* print an error msg when devm_pinctrl_get() returns an error that
is not -EPROBE_DEFER.
* print a dbg msg if devm_pinctrl_get() return NULL. 

V1 -> V2:
* remove the unnecessary 'if (!rinfo->pinctrl)' test
* test if return is -EPROBE_DEFER, in that case, return it.
* Reword the commit message according to review

 drivers/i2c/busses/i2c-designware-master.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c
index b720fcc5c10a..30b2de829a32 100644
--- a/drivers/i2c/busses/i2c-designware-master.c
+++ b/drivers/i2c/busses/i2c-designware-master.c
@@ -17,6 +17,7 @@
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/module.h>
+#include <linux/pinctrl/consumer.h>
 #include <linux/pm_runtime.h>
 #include <linux/regmap.h>
 #include <linux/reset.h>
@@ -855,6 +856,17 @@ static int i2c_dw_init_recovery_info(struct dw_i2c_dev *dev)
 		return PTR_ERR(gpio);
 	rinfo->sda_gpiod = gpio;
 
+	rinfo->pinctrl = devm_pinctrl_get(dev->dev);
+	if (IS_ERR(rinfo->pinctrl)) {
+		if (PTR_ERR(rinfo->pinctrl) == -EPROBE_DEFER)
+			return PTR_ERR(rinfo->pinctrl);
+
+		rinfo->pinctrl = NULL;
+		dev_err(dev->dev, "getting pinctrl info failed: bus recovery might not work\n");
+	} else if (!rinfo->pinctrl) {
+		dev_dbg(dev->dev, "pinctrl is disabled, bus recovery might not work\n");
+	}
+
 	rinfo->recover_bus = i2c_generic_scl_recovery;
 	rinfo->prepare_recovery = i2c_dw_prepare_recovery;
 	rinfo->unprepare_recovery = i2c_dw_unprepare_recovery;
-- 
2.17.1