Am Mittwoch, 7. August 2024, 14:16:48 CEST schrieb Laurent Pinchart: > ******************** > Achtung externe E-Mail: Öffnen Sie Anhänge und Links nur, wenn Sie wissen, dass diese aus einer sicheren Quelle stammen und sicher sind. Leiten Sie die E-Mail im Zweifelsfall zur Prüfung an den IT-Helpdesk weiter. > Attention external email: Open attachments and links only if you know that they are from a secure source and are safe. In doubt forward the email to the IT-Helpdesk to check it. > ******************** > > On Wed, Aug 07, 2024 at 02:12:04PM +0200, Alexander Stein wrote: > > Am Mittwoch, 7. August 2024, 13:07:24 CEST schrieb Benjamin Bara: > > > On Wed, 7 Aug 2024 at 11:50, Laurent Pinchart 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 > > > > Okay, this is from a imx327lqr: > > > > [ 15.265086] imx290 3-001a: chip ID 0x07d0 > > > > Doesn't look like an ID register to me. > > Indeed, it's quite suspicious. > > I wonder if we could find a more applicable register. Chip ID registers > are usually located at the beginning or end of the register space, we > could have a look there. Dumping all registers (8-Bit reads) from 0x3001 till 0x3480 only has a few non-zero registers: > # cat /sys/kernel/debug/regmap/3-001a/range > 3000-3480 > # cat /sys/kernel/debug/regmap/3-001a/registers | grep -v ": 00" > 3000: 01 > 3020: 01 > 303c: 08 > 303e: 38 > 303f: 04 > 3040: 08 > 3042: 80 > 3043: 07 > 319a: d0 > 319b: 07 > 3418: 38 > 3419: 04 > 3472: 80 > 3473: 07 Note I am on a Vision Components imx327, which might block some reads. Laurent is also aware of that behaviour. But maybe this list gives an indicator. Best regards, Alexander -- TQ-Systems GmbH | Mühlstraße 2, Gut Delling | 82229 Seefeld, Germany Amtsgericht München, HRB 105018 Geschäftsführer: Detlef Schneider, Rüdiger Stahl, Stefan Schneider http://www.tq-group.com/
