linux-kernel - [PATCH v4 2/2] media: imx335: Fix reset-gpio handling

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Message-Id: <20240830-imx335-vflip-v4-2-cb9f20fc7b87@ideasonboard.com>
Date: Fri, 30 Aug 2024 11:41:52 +0530
From: Umang Jain <umang.jain@...asonboard.com>
To: Mauro Carvalho Chehab <mchehab@...nel.org>, 
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, Shawn Guo <shawnguo@...nel.org>, 
 Sascha Hauer <s.hauer@...gutronix.de>, 
 Pengutronix Kernel Team <kernel@...gutronix.de>, 
 Fabio Estevam <festevam@...il.com>, 
 "Paul J. Murphy" <paul.j.murphy@...el.com>, 
 Daniele Alessandrelli <daniele.alessandrelli@...el.com>, 
 Sakari Ailus <sakari.ailus@...ux.intel.com>, 
 Martina Krasteva <martinax.krasteva@...el.com>
Cc: linux-media@...r.kernel.org, devicetree@...r.kernel.org, 
 imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org, 
 linux-kernel@...r.kernel.org, 
 Mauro Carvalho Chehab <mchehab+huawei@...nel.org>, 
 Kieran Bingham <kieran.bingham@...asonboard.com>, 
 Laurent Pinchart <laurent.pinchart@...asonboard.com>, 
 Umang Jain <umang.jain@...asonboard.com>, stable@...r.kernel.org
Subject: [PATCH v4 2/2] media: imx335: Fix reset-gpio handling

Rectify the logical value of reset-gpio so that it is set to
0 (disabled) during power-on and to 1 (enabled) during power-off.

Set the reset-gpio to GPIO_OUT_HIGH at initialization time to make
sure it starts off in reset. Also drop the "Set XCLR" comment which
is not-so-informative.

The existing usage of imx335 had reset-gpios polarity inverted
(GPIO_ACTIVE_HIGH) in their device-tree sources. With this patch
included, those DTS will not be able to stream imx335 anymore. The
reset-gpio polarity will need to be rectified in the device-tree
sources as shown in [1] example, in order to get imx335 functional
again (as it remains in reset prior to this fix).

Cc: stable@...r.kernel.org
Fixes: 45d19b5fb9ae ("media: i2c: Add imx335 camera sensor driver")
Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
Link: https://lore.kernel.org/linux-media/20240729110437.199428-1-umang.jain@ideasonboard.com/
Signed-off-by: Umang Jain <umang.jain@...asonboard.com>
---
Following conclusions has been observed and discussed [2]:

- Original driver was reviewed [3] but, the improper handling of
  reset-gpios was missed in review.
- Commit fea91ee73b7c ("media: i2c: imx335: Enable regulator supplies")
  shows the driver didn't had regulator enablement support. The driver
  would have only worked for cases when the supplies were always-on.
- Commit 14a60786d72e ("media: imx335: Set reserved register to default value")
  reflects that the imx335 driver was un-usable due to a reserved
  register not been set to default.
- The original author is no longer using the driver nor it is used for its
  original purpose any more (confirmed by Sakari Ailus).
- It's extremely unlikely the driver has been or continues to be in
  use on ACPI based systems (comment by Sakari Ailus).

The above discussion points in a direction that driver does not cater
to a large user-base. Nonetheless, the breakage will be noticed by a few
users (if at all) hence, this explanation would help resolve the breakage
as soon as noticed (by using correct reset-gpio polarity as mentioned
in [1]).

[1]: Documentation/devicetree/bindings/media/i2c/sony,imx335.yaml
[2]: https://lore.kernel.org/linux-media/20240729110437.199428-1-umang.jain@ideasonboard.com/
[3]: https://lore.kernel.org/all/20210527142145.173-3-martinax.krasteva@linux.intel.com/
---
---
 drivers/media/i2c/imx335.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/media/i2c/imx335.c b/drivers/media/i2c/imx335.c
index 990d74214cc2..54a1de53d497 100644
--- a/drivers/media/i2c/imx335.c
+++ b/drivers/media/i2c/imx335.c
@@ -997,7 +997,7 @@ static int imx335_parse_hw_config(struct imx335 *imx335)

 	/* Request optional reset pin */
 	imx335->reset_gpio = devm_gpiod_get_optional(imx335->dev, "reset",
-						     GPIOD_OUT_LOW);
+						     GPIOD_OUT_HIGH);
 	if (IS_ERR(imx335->reset_gpio)) {
 		dev_err(imx335->dev, "failed to get reset gpio %ld\n",
 			PTR_ERR(imx335->reset_gpio));
@@ -1110,8 +1110,7 @@ static int imx335_power_on(struct device *dev)

 	usleep_range(500, 550); /* Tlow */

-	/* Set XCLR */
-	gpiod_set_value_cansleep(imx335->reset_gpio, 1);
+	gpiod_set_value_cansleep(imx335->reset_gpio, 0);

 	ret = clk_prepare_enable(imx335->inclk);
 	if (ret) {
@@ -1124,7 +1123,7 @@ static int imx335_power_on(struct device *dev)
 	return 0;

 error_reset:
-	gpiod_set_value_cansleep(imx335->reset_gpio, 0);
+	gpiod_set_value_cansleep(imx335->reset_gpio, 1);
 	regulator_bulk_disable(ARRAY_SIZE(imx335_supply_name), imx335->supplies);

 	return ret;
@@ -1141,7 +1140,7 @@ static int imx335_power_off(struct device *dev)
 	struct v4l2_subdev *sd = dev_get_drvdata(dev);
 	struct imx335 *imx335 = to_imx335(sd);

-	gpiod_set_value_cansleep(imx335->reset_gpio, 0);
+	gpiod_set_value_cansleep(imx335->reset_gpio, 1);
 	clk_disable_unprepare(imx335->inclk);
 	regulator_bulk_disable(ARRAY_SIZE(imx335_supply_name), imx335->supplies);

-- 
2.45.0