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. -- Regards, Laurent Pinchart
