Moi, On Fri, Mar 22, 2024 at 08:50:00AM +0200, Tomi Valkeinen wrote: > On 20/03/2024 00:33, Laurent Pinchart wrote: > > On Tue, Mar 19, 2024 at 04:20:35PM +0200, Tomi Valkeinen wrote: > > > On 19/03/2024 15:27, Sakari Ailus wrote: > > > > On Thu, Mar 14, 2024 at 09:30:50AM +0200, Tomi Valkeinen wrote: > > > > > On 13/03/2024 09:24, Sakari Ailus wrote: > > > > > > Add generic serial metadata mbus formats. These formats describe data > > > > > > width and packing but not the content itself. The reason for specifying > > > > > > such formats is that the formats as such are fairly device specific but > > > > > > they are still handled by CSI-2 receiver drivers that should not be aware > > > > > > of device specific formats. What makes generic metadata formats possible > > > > > > is that these formats are parsed by software only, after capturing the > > > > > > data to system memory. > > > > > > > > > > > > Also add a definition for "Data unit" to cover what is essentially a pixel > > > > > > but is not image data. > > > > > > > > > > The CCS spec talks about legacy packing and optimized packing for 16+ bit > > > > > formats. You cover only the "legacy" ones here. Did you look at those? > > > > > > > > The reason is that the bus data layout of the new packing at higher bit > > > > depth matches with packing at lower bit depths (half to be precise). That's > > > > why there's no need to define formats for the new packing methods at higher > > > > bit depths (the driver simply uses the packing at half of the bit depth). > > > > > > Hmm. If we're capturing 10-bit raw format, say, with the width of 640 > > > pixels, we'll configure the video stream format according to those. For > > > the embedded stream, we'll set it to V4L2_META_FMT_GENERIC_CSI2_10 and > > > 640 width, right? > > > > > > If we're capturing 20-bit raw, we'll configure the video stream format > > > again accordingly, width to 640, and 20 bit fourcc/mbus code. If the > > > embedded stream uses the "legacy" packing, we'll set the format to > > > V4L2_META_FMT_GENERIC_CSI2_20 with width of 640, right? > > > > > > But if it's using packed format for the embedded stream, we set the > > > format to V4L2_META_FMT_GENERIC_CSI2_10 and width to 1280? > > > > > > Considering that the video and (line-based) embedded data come from the > > > same source, I'd expect the widths to be the same. > > > > I don't have a strong objection against multiplying the width, but we > > need to figure out the impact on other kernel space components, as well > > as on userspace. I suppose the media bus code for the embedded data > > stream on the sensor source pad when using optimized packing and > > capturing RAW20 images would be MEDIA_BUS_FMT_META_10 ? In that case I > > think the sensor driver should be able to handle the width calculations > > on its own, and the value would just be propagated by userspace. > > Yes, I think it works. I just find it more logical if the widths of both the > video and embedded streams are the same (which is the case for all other > embedded formats). > > However, even the CCS spec says "for RAW16, RAW20, and/or RAW24 Visible > pixels, top-embedded data may instead be more optimally packed using RAW8, > RAW10, and/or RAW12 pixels", so that's in line with what Sakari suggests. > Although the spec specifically says "top-embedded", so does it mean that the > optimized data is not allowed for bottom data? I haven't read the spec regarding this but I don't think there should be anything that prevents it: it's the embedded data format. The CCS driver patches only adds support for the top embedded data anyway. -- Regards, Sakari Ailus
