2023-03-23 22:51:22

by Ricardo Ribalda

Subject: [PATCH] media: ov8856: Do not check for for module version

It the device is probed in non-zero ACPI D state, the module
identification is delayed until the first streamon.

The module identification has two parts: deviceID and version. To rea
the version we have to enable OTP read. This cannot be done during
streamon, becase it modifies REG_MODE_SELECT.

Since the driver has the same behaviour for all the module versions, do
not read the module version from the sensor's OTP.

Cc: [email protected]
Fixes: 0e014f1a8d54 ("media: ov8856: support device probe in non-zero ACPI D state")
Signed-off-by: Ricardo Ribalda <[email protected]>
---
To: Dongchun Zhu <[email protected]>
To: Mauro Carvalho Chehab <[email protected]>
To: Sakari Ailus <[email protected]>
To: Bingbu Cao <[email protected]>
Cc: Max Staudt <[email protected]>
Cc: Jimmy Su <[email protected]>
Cc: Mauro Carvalho Chehab <[email protected]>
Cc: [email protected]
Cc: [email protected]
---
drivers/media/i2c/ov8856.c | 40 ----------------------------------------
1 file changed, 40 deletions(-)

diff --git a/drivers/media/i2c/ov8856.c b/drivers/media/i2c/ov8856.c
index cf8384e09413..b5c7881383ca 100644
--- a/drivers/media/i2c/ov8856.c
+++ b/drivers/media/i2c/ov8856.c
@@ -1709,46 +1709,6 @@ static int ov8856_identify_module(struct ov8856 *ov8856)
return -ENXIO;
}

- ret = ov8856_write_reg(ov8856, OV8856_REG_MODE_SELECT,
- OV8856_REG_VALUE_08BIT, OV8856_MODE_STREAMING);
- if (ret)
- return ret;
-
- ret = ov8856_write_reg(ov8856, OV8856_OTP_MODE_CTRL,
- OV8856_REG_VALUE_08BIT, OV8856_OTP_MODE_AUTO);
- if (ret) {
- dev_err(&client->dev, "failed to set otp mode");
- return ret;
- }
-
- ret = ov8856_write_reg(ov8856, OV8856_OTP_LOAD_CTRL,
- OV8856_REG_VALUE_08BIT,
- OV8856_OTP_LOAD_CTRL_ENABLE);
- if (ret) {
- dev_err(&client->dev, "failed to enable load control");
- return ret;
- }
-
- ret = ov8856_read_reg(ov8856, OV8856_MODULE_REVISION,
- OV8856_REG_VALUE_08BIT, &val);
- if (ret) {
- dev_err(&client->dev, "failed to read module revision");
- return ret;
- }
-
- dev_info(&client->dev, "OV8856 revision %x (%s) at address 0x%02x\n",
- val,
- val == OV8856_2A_MODULE ? "2A" :
- val == OV8856_1B_MODULE ? "1B" : "unknown revision",
- client->addr);
-
- ret = ov8856_write_reg(ov8856, OV8856_REG_MODE_SELECT,
- OV8856_REG_VALUE_08BIT, OV8856_MODE_STANDBY);
- if (ret) {
- dev_err(&client->dev, "failed to exit streaming mode");
- return ret;
- }
-
ov8856->identified = true;

return 0;

---
base-commit: 9fd6ba5420ba2b637d1ecc6de8613ec8b9c87e5a
change-id: 20230323-ov8856-otp-112f3cdc74b1

Best regards,
--
Ricardo Ribalda <[email protected]>

2023-03-31 09:00:19

by Sakari Ailus

Subject: Re: [PATCH] media: ov8856: Do not check for for module version

Hi Ricardo,

On Thu, Mar 23, 2023 at 11:44:20PM +0100, Ricardo Ribalda wrote:
> It the device is probed in non-zero ACPI D state, the module
> identification is delayed until the first streamon.
>
> The module identification has two parts: deviceID and version. To rea
> the version we have to enable OTP read. This cannot be done during
> streamon, becase it modifies REG_MODE_SELECT.
>
> Since the driver has the same behaviour for all the module versions, do
> not read the module version from the sensor's OTP.
>
> Cc: [email protected]
> Fixes: 0e014f1a8d54 ("media: ov8856: support device probe in non-zero ACPI D state")
> Signed-off-by: Ricardo Ribalda <[email protected]>

I guess the identification could be done from pre_streamon() callback
instead, but the driver doesn't implement it. But the information isn't
used for anything indeed so I'll just take this.

Thanks.

--
Kind regards,

Sakari Ailus