Hi! On Wed, 7 Aug 2024 at 11:50, Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> wrote: > On Wed, Aug 07, 2024 at 10:47:39AM +0200, Benjamin Bara wrote: > > On Wed, 7 Aug 2024 at 10:33, Alexander Stein wrote: > > > Am Mittwoch, 7. August 2024, 10:10:28 CEST schrieb Benjamin Bara: > > > > Currently, the V4L2 subdevice is also created when the device is not > > > > available/connected. In this case, dmesg shows the following: > > > > > > > > [ 10.419510] imx290 7-001a: Error writing reg 0x301c: -6 > > > > [ 10.428981] imx290 7-001a: Error writing reg 0x3020: -6 > > > > [ 10.442712] imx290 7-001a: Error writing reg 0x3018: -6 > > > > [ 10.454018] imx290 7-001a: Error writing reg 0x3020: -6 > > > > > > > > which seems to come from imx290_ctrl_update() after the subdev init is > > > > finished. However, as the errors are ignored, the subdev is initialized > > > > but simply does not work. From userspace perspective, there is no > > > > visible difference between a working and not-working subdevice (except > > > > when trying it out or watching for the error message). > > > > > > > > This commit adds a simple availability check before starting with the > > > > subdev initialization to error out instead. > > > > > > There is already a patch reading the ID register at [1]. This also reads the > > > ID register. But I don't have any documentation regarding that register, > > > neither address nor values definitions. If there is known information about > > > that I would prefer reading the ID and compare it to expected values. > > > > Thanks for the link - it seems like Laurent has dropped the patch for > > the more recent kernel versions on their GitLab. > > It was a patch that I wrote as a test, and I decided not to upstream it > as it had limited value to me. The downside with reading registers at > probe time is that you have to power up the sensor. This can have > undesired side effects, such as flashing a privacy LED on at boot time > in devices that have one. There's also the increase in boot time due to > the power up sequence, which one may want to avoid. > > The imx290 driver already powers up the device unconditionally at probe > time, so reading the version register wouldn't be much of an issue I > suppose. I would be fine merging that patch. > > > This was also my initial intention, but similar to you, I don't have a > > docu describing this register, so I am not sure where the info is coming > > from and if it really contains the identification/type info. Probably > > Laurent has more infos on that. > > That's a good question. I don't see a mention of that register in the > IMX290 datasheet I've found online > (https://static6.arrow.com/aropdfconversion/c0c7efde6571c768020a72f59b226308b9669e45/sony_imx290lqr-c_datasheet.pdf). > Looking at the git history, the IMX290_CHIP_ID register macro was > introduced in an unrelated commit, without an explanation. I don't > recall where it comes from, but I don't think I've added it randomly. It > may have come from an out-of-tree driver. Thanks for the info! > I don't have an IMX290 plugged in at the moment, what's the value of the > register ? I currently have an imx462 available, which is not "officially supported" yet, but basically an imx290 derivative. With your patch applied: [ 10.424187] imx290 7-001a: chip ID 0x07d0 Best regards Benjamin > > > > [1] https://gitlab.com/ideasonboard/nxp/linux/-/commit/85ce725f1de7c16133bfb92b2ab0d3d84efcdb47 > > > > > > > Signed-off-by: Benjamin Bara <benjamin.bara@xxxxxxxxxxx> > > > > --- > > > > drivers/media/i2c/imx290.c | 5 +++++ > > > > 1 file changed, 5 insertions(+) > > > > > > > > diff --git a/drivers/media/i2c/imx290.c b/drivers/media/i2c/imx290.c > > > > index 4150e6e4b9a6..a86076e42a36 100644 > > > > --- a/drivers/media/i2c/imx290.c > > > > +++ b/drivers/media/i2c/imx290.c > > > > @@ -1580,6 +1580,11 @@ static int imx290_probe(struct i2c_client *client) > > > > pm_runtime_set_autosuspend_delay(dev, 1000); > > > > pm_runtime_use_autosuspend(dev); > > > > > > > > + /* Make sure the sensor is available before V4L2 subdev init. */ > > > > + ret = cci_read(imx290->regmap, IMX290_STANDBY, NULL, NULL); > > > > + if (ret) > > > > + goto err_pm; > > > > + > > > > /* Initialize the V4L2 subdev. */ > > > > ret = imx290_subdev_init(imx290); > > > > if (ret)
