[PATCH v2] UPSTREAM: media: ov8856: skip OTP read in non-zero ACPI D state

[PATCH v2] UPSTREAM: media: ov8856: skip OTP read in non-zero ACPI D state

[Jimmy Su]

To skip OTP read function while enable non-zero ACPI D state.
This OTP read only influences streaming output with 3280x2464 &
1640x1232 resolution.

Signed-off-by: Jimmy Su <jimmy.su@intel.com>
Reported-by: kernel test robot <lkp@intel.com>
---
 drivers/media/i2c/ov8856.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/media/i2c/ov8856.c b/drivers/media/i2c/ov8856.c
index 8785764b7a74..f1bb7d882183 100644
--- a/drivers/media/i2c/ov8856.c
+++ b/drivers/media/i2c/ov8856.c
@@ -1448,6 +1448,9 @@ struct ov8856 {
 
 	/* True if the device has been identified */
 	bool identified;
+
+	/* True for skipping otp read */
+	bool acpi_skip_otp;
 };
 
 struct ov8856_lane_cfg {
@@ -1692,7 +1695,7 @@ static int ov8856_identify_module(struct ov8856 *ov8856)
 {
 	struct i2c_client *client = v4l2_get_subdevdata(&ov8856->sd);
 	int ret;
-	u32 val;
+	u32 val, width;
 
 	if (ov8856->identified)
 		return 0;
@@ -1708,6 +1711,10 @@ static int ov8856_identify_module(struct ov8856 *ov8856)
 		return -ENXIO;
 	}
 
+	width = ov8856->cur_mode->width;
+	if (ov8856->acpi_skip_otp & ((width == 3280) | (width == 1640)))
+		goto otp_skip;
+
 	ret = ov8856_write_reg(ov8856, OV8856_REG_MODE_SELECT,
 			       OV8856_REG_VALUE_08BIT, OV8856_MODE_STREAMING);
 	if (ret)
@@ -1750,6 +1757,11 @@ static int ov8856_identify_module(struct ov8856 *ov8856)
 
 	ov8856->identified = true;
 
+	return 0;
+
+otp_skip:
+	ov8856->identified = true;
+
 	return 0;
 }
 
@@ -2499,6 +2511,8 @@ static int ov8856_probe(struct i2c_client *client)
 			dev_err(&client->dev, "failed to find sensor: %d", ret);
 			goto probe_power_off;
 		}
+	} else {
+		ov8856->acpi_skip_otp = true;
 	}
 
 	mutex_init(&ov8856->mutex);
-- 
2.17.1

Re: [PATCH v2] UPSTREAM: media: ov8856: skip OTP read in non-zero ACPI D state

[Dan Carpenter]

Hi Jimmy,

url:    https://github.com/intel-lab-lkp/linux/commits/Jimmy-Su/UPSTREAM-media-ov8856-skip-OTP-read-in-non-zero-ACPI-D-state/20220510-232606
base:   git://linuxtv.org/media_tree.git master
config: nios2-randconfig-m031-20220512 (https://download.01.org/0day-ci/archive/20220513/202205131109.giBGpLnO-lkp@intel.com/config)
compiler: nios2-linux-gcc (GCC) 11.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>

smatch warnings:
drivers/media/i2c/ov8856.c:1715 ov8856_identify_module() warn: maybe use && instead of &

vim +1715 drivers/media/i2c/ov8856.c

0e014f1a8d546f Bingbu Cao 2021-12-15  1694  static int ov8856_identify_module(struct ov8856 *ov8856)
0e014f1a8d546f Bingbu Cao 2021-12-15  1695  {
0e014f1a8d546f Bingbu Cao 2021-12-15  1696  	struct i2c_client *client = v4l2_get_subdevdata(&ov8856->sd);
0e014f1a8d546f Bingbu Cao 2021-12-15  1697  	int ret;
25bf233398211c Jimmy Su   2022-05-10  1698  	u32 val, width;
0e014f1a8d546f Bingbu Cao 2021-12-15  1699  
0e014f1a8d546f Bingbu Cao 2021-12-15  1700  	if (ov8856->identified)
0e014f1a8d546f Bingbu Cao 2021-12-15  1701  		return 0;
0e014f1a8d546f Bingbu Cao 2021-12-15  1702  
0e014f1a8d546f Bingbu Cao 2021-12-15  1703  	ret = ov8856_read_reg(ov8856, OV8856_REG_CHIP_ID,
0e014f1a8d546f Bingbu Cao 2021-12-15  1704  			      OV8856_REG_VALUE_24BIT, &val);
0e014f1a8d546f Bingbu Cao 2021-12-15  1705  	if (ret)
0e014f1a8d546f Bingbu Cao 2021-12-15  1706  		return ret;
0e014f1a8d546f Bingbu Cao 2021-12-15  1707  
0e014f1a8d546f Bingbu Cao 2021-12-15  1708  	if (val != OV8856_CHIP_ID) {
0e014f1a8d546f Bingbu Cao 2021-12-15  1709  		dev_err(&client->dev, "chip id mismatch: %x!=%x",
0e014f1a8d546f Bingbu Cao 2021-12-15  1710  			OV8856_CHIP_ID, val);
0e014f1a8d546f Bingbu Cao 2021-12-15  1711  		return -ENXIO;
0e014f1a8d546f Bingbu Cao 2021-12-15  1712  	}
0e014f1a8d546f Bingbu Cao 2021-12-15  1713  
25bf233398211c Jimmy Su   2022-05-10  1714  	width = ov8856->cur_mode->width;
25bf233398211c Jimmy Su   2022-05-10 @1715  	if (ov8856->acpi_skip_otp & ((width == 3280) | (width == 1640)))

I think Smatch will not print a warning for this if ->acpi_skip_otp is
declared as bool or if Smatch can determine that it is boolean from
the context, but the kbuild-bot does not do cross function analysis.

But to a human, the naming seems pretty likely that ov8856->acpi_skip_otp
so && and & are equivalent.

However && is more readable.

25bf233398211c Jimmy Su   2022-05-10  1716  		goto otp_skip;
25bf233398211c Jimmy Su   2022-05-10  1717  
0e014f1a8d546f Bingbu Cao 2021-12-15  1718  	ret = ov8856_write_reg(ov8856, OV8856_REG_MODE_SELECT,
0e014f1a8d546f Bingbu Cao 2021-12-15  1719  			       OV8856_REG_VALUE_08BIT, OV8856_MODE_STREAMING);
0e014f1a8d546f Bingbu Cao 2021-12-15  1720  	if (ret)
0e014f1a8d546f Bingbu Cao 2021-12-15  1721  		return ret;
0e014f1a8d546f Bingbu Cao 2021-12-15  1722  
0e014f1a8d546f Bingbu Cao 2021-12-15  1723  	ret = ov8856_write_reg(ov8856, OV8856_OTP_MODE_CTRL,
0e014f1a8d546f Bingbu Cao 2021-12-15  1724  			       OV8856_REG_VALUE_08BIT, OV8856_OTP_MODE_AUTO);
0e014f1a8d546f Bingbu Cao 2021-12-15  1725  	if (ret) {
0e014f1a8d546f Bingbu Cao 2021-12-15  1726  		dev_err(&client->dev, "failed to set otp mode");
0e014f1a8d546f Bingbu Cao 2021-12-15  1727  		return ret;
0e014f1a8d546f Bingbu Cao 2021-12-15  1728  	}
0e014f1a8d546f Bingbu Cao 2021-12-15  1729  

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp

Re: [PATCH v2] UPSTREAM: media: ov8856: skip OTP read in non-zero ACPI D state

[Sakari Ailus]

Hi Jimmy,

On Tue, May 10, 2022 at 11:12:41PM +0800, Jimmy Su wrote:
> To skip OTP read function while enable non-zero ACPI D state.
> This OTP read only influences streaming output with 3280x2464 &
> 1640x1232 resolution.

This isn't the right way to fix the problem.

Reading the EEPROM (and thus starting streaming) is a problem since the
receiver has been already set up to receive a proper frame. EEPROM reading
should be instead moved to pre_streamon callback.

I suppose this way the sensor's CSI-2 TX is also set in LP-11 mode, as many
CSI-2 receivers expect.

-- 
Kind regards,

Sakari Ailus