08:49 <lfa> Hi. I'm experimenting with h264 decoding of the iMX8M Plus. From what I saw, it uses the Hantro G1, as does the iMX8M Quad. NXP specifies 1920x1080 as max supported resolution on the iMX8MP, and 4K on the iMX8MQ

08:49 <lfa> And indeed, when I try to decode a stream with 1922x1080 (2 pixels additional width), it doesn't work anymore

08:49 <lfa> Does by any chance someone know if 1080p is a hard limitation of the silicon, or could it be worth it to poke around to see if this limitation can be lifted?

09:00 <lynxeye> lfa: While I don't know for sure, I would expect this to be a market segmentation thing. So my guess is that the decoder IP is really limited to 1080p via fuses or a synthesis option.

09:03 <lfa> lynxeye: right, that's also a bit my suspicion, seeing that just two more pixels "break" it. Also reducing the height doesn't make a difference. So it's also not about overall pixel count

10:11 <dv_> lfa: are you using the mainline kernel for this?

10:48 <lfa> dv_: right now I'm trying with the NXP kernel. sorry, forgot to mention that

14:37 <cphealy> lfa: there are some fuses in the G1 and G2 for what the max width are supported. On the i.MX8M, it supports 4K. Likely on the later i.MX8M variants, they set the limit to 1920 width to save die area.

14:39 <cphealy> The fuses for 4k vs 1920 or whatnot are defined in the G1 and G2 sections of the relevant i.MX8M* reference manual.

15:40 <lfa> cphealy: thanks for the clue. I see that there are two fuses FUSE_DEC_MA

15:40 <lfa> XW_4K and FUSE_DEC_MA

15:40 <lfa> XW_1920. However, both are "enabled" for both the iMX8MP and iMX8MQ acc. to the reference manual

15:41 <lfa> not really trusting the reference manual too much though

15:45 <cphealy> Perhaps it's disabled in the NXP SW stack then? You might want to jump over to #linux-media where the folks working on the upstream Hantro G1 and G2 drivers hang out and ask there.

16:20 <lfa> Just saw there's another register called "Synthesis configuration register decoder 0" with a field SW_DEC_MAX_OWIDTH that's set to 1920 on the iMX8MP

22:04 <cphealy> lfa: There you go. It would probably be nice to have the upstream hantro decoder driver probe these regs and dump the caps as part of the probe function.