On Wed, Oct 18, 2023 at 09:27:59AM +0000, Sakari Ailus wrote: > On Wed, Oct 18, 2023 at 12:04:46PM +0530, Umang Jain wrote: > > Hello everyone, > > > > Past few weeks I have been working to support IMX519 sensor with CCS > > driver. The highlight is that I can capture frames with CCS driver now, > > with a few workarounds. This thread summarises the issues that we faced > > and act as placeholder for more open and structured discussion. > > > > - First open question is regarding the upstream support of a sensor > > driver with CCS. How should we term that a sensor is 'mainline-supported' > > if it is getting supported by CCS. How can one use a sensor out of the box > > with mainline kernel, when supported by CCS? > > If the sensor is fully compliant, it should "just work", but then there's > the question of CCS static data if the sensor needs it. > > For devices that aren't fully compliant this is a more complicated > question. Some devices might work with some parameters only, in particular > horizontal blanking is a sensitive value. The approach here should be to > set minimum and maximum to the same value to force horizontal blanking > value that is known to work. The if rules could be used for this as well. > > > > > - Continued from the previous discusion point, the more specific question is > > about the sensor-specific static data that is composed of > > manfacturer-specific-registers (MSRs) and (maybe) overridden > > sensor-read-only-regs which are created as part of ccs-tools [1]. > > This becomes part of firmware? which needs to live /lib/firmware and > > then picked up by CCS driver. > > > > Where can they be centralized ? is linux-firmware an option? [2]. > > I'd favour this. linux-firmware could host the binary files, but how about the YAML sources ? > > - It was noticed that with current version of CCS - I was only able to > > get 1/3 buffer filled. This was due to the fact that LINE_LENGTH_PCK > > and FRAME_LENGTH_LINES registers are not getting updated to permissible > > values in / before ccs_start_streaming() starts. Hence they are stuck > > with values from probe time. > > If you're not changing vertical or horizontal blanking, these are likely > the correct values from driver perspective. If these values do not work > however, then you most likely have an issue with sensor provided limit and > capability information. This should be fixed using CCS static data. I may have understood Umang incorrectly, but I thought he meant that the driver doesn't program those registers if the controls are not changed by userspace, and the register power-up default values are not right. Umang, is my understanding wrong ? > > These are top issues we faced while trying to support IMX519. This thread > > will act as placeholder to have more discussions in the open and/or help > > other sensors that can be supported with CCS. > > I'm happy to see you using the CCS driver on a sensor I haven't used > before. The above issues, while they prevent meaningfully using the sensor > right now, they also seem easy to resolve. > > Additionally --- if the sensor does not provide meaningful values for its > vendor and model, we could use the device's compatible string as the basis > for the firmware file name. I can post a patch for this. -- Regards, Laurent Pinchart
