The pixel array can read out the full 4056x3040 array at 60fps at 12bpp, as per the product brief1) Thanks for your timely response, but what we are curious about how IMX477_PIXEL_RATE(840000000) coming out. as we know on Raspberry Pi High Quality Camera ,there are only two lanes for data transition, maximum bit rate per lane is about 2.1Gbps, total 4.2 Gbps on HQ Camera module, the maximum pixel rate is 420000000 under 10bits RAW mode in theory. Would you help check if there are something wrong?
It also says that the MIPI block of the sensor specification is MIPI 2lane/4lane, Max. 2.1 Gbps/lane, D-PHY spec. ver. 1.2 compliant.
4050x3040 * 12bpp * 60Hz = 8.877Gbit/s. 4 lanes at 2.1Gbit/s/lane would be 8.4Gbit/s, so it may be limited to 10bpp to achieve full rate (7.4Gbit/s)
The Pi only exposes 2 data lanes, with each lane on Pi0-4 able to run at up to 1Gbit/s, so that imposes the limit on max throughput.
As I said, the sensor and MIPI blocks can run at different rates as there is a FIFO between the two.
To make life simpler, the recommendation by Sony was to leave the pixel array running at their default speed but with extended HBLANK to allow the MIPI block to get rid of the data whilst running at the lower rate.
There is a PR at https://github.com/raspberrypi/linux/pull/6208 that does rejig the MIPI PLL settings to double the link frequency as Pi5's CSI receiver is specified to work up to 1.5Gbit/s/lane. That also reduces the HBLANK to compensate for the increased MIPI rate.
Sorry, no I'm not going to delve into the register configuration.2)we suppose exteral clock is 24MHz, IOP_PREPLLCK_DIV is 2 , IOP_PLL_MPY is 150, IOPCK = 1800MHz, CSI2 interface clock is generated from IOPCK by divding into 1/2(we are not sure what divider is because no specific datasheet descripted it ) , base on the IOPCK ,actual maximum pixel rate is 360000000 under 10bits RAW mode, right?
3)As you know, it is a very large HBLANK values for IMX477, it is more than the raw 4056 active pixels,
and from the source code(imx477.c), the line_length_pix=0x5dc0 and 0x31c4 6664, how do these three data(0x5dc0 0x31c4 6664) come from, could you explain it in more detail?
Statistics: Posted by 6by9 — Thu Aug 01, 2024 10:32 am
