Hi Matt, On 28/10/16 22:14, Matt Ranostay wrote:
So want to toss a few thoughts on adding support for thermopile devices (could be used for FLIR Lepton as well) that output pixel data. These typically aren't DMA'able devices since they are low speed (partly to limiting the functionality to be in compliance with ITAR) and data is piped over i2c/spi. My question is that there doesn't seem to be an other driver that polls frames off of a device and pushes it to the video buffer, and wanted to be sure that this doesn't currently exist somewhere.
Not anymore, but if you go back to kernel 3.6 then you'll find this driver: drivers/media/video/bw-qcam.c It was for a grayscale parallel port webcam (which explains why it was removed in 3.7 :-) ), and it used polling to get the pixels.
Also more importantly does the mailing list thinks it belongs in v4l2?
I think it fits. It's a sensor, just with a very small resolution and infrared
instead of visible light.
We already came up the opinion on the IIO list that it doesn't belong in that subsystem since pushing raw pixel data to a buffer is a bit hacky. Also could be generically written with regmap so other devices (namely FLIR Lepton) could be easily supported. Need some input for the video pixel data types, which the device we are using (see datasheet links below) is outputting pixel data in little endian 16-bit of which a 12-bits signed value is used. Does it make sense to do some basic processing on the data since greyscale is going to look weird with temperatures under 0C degrees? Namely a cold object is going to be brighter than the hottest object it could read.
Or should a new V4L2_PIX_FMT_* be defined and processing done in software?
I would recommend that. It's no big deal, as long as the new format is documented.
Another issue is how to report the scaling value of 0.25 C for each LSB of the pixels to the respecting recording application.
Probably through a read-only control, but I'm not sure. Regards, Hans
Datasheet: http://media.digikey.com/pdf/Data%20Sheets/Panasonic%20Sensors%20PDFs/Grid-EYE_AMG88.pdf Datasheet: https://eewiki.net/download/attachments/13599167/Grid-EYE%20SPECIFICATIONS%28Reference%29.pdf?version=1&modificationDate=1380660426690&api=v2 Thanks, Matt -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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