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timvideos / linux-litex

Linux Kernel designed to run on the HDMI2USB-misoc-firmware with or1k arch.
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Connect the DisplayPort AUX channel up to Linux #7

Open mithro opened 7 years ago

mithro commented 7 years ago

One of the big things that Linux has is decent support for understanding the stuff stored in the DisplayPort's equivalent of EDID. We should get that working and see what it decodes and stuff.

mithro commented 7 years ago

The only auxch APIs I've seen are pretty highlevel, mostly taking 20 byte packets, (make sure you do at least 20 bytes) and generally are modelled like i2c engines, you give it a packet and it gives you an irq/status, and you get an irq and read the packet. Having some sort of interrupt line is definitely useful.

> The i915 and radeon auxch hw APIs https://github.com/torvalds/linux/blob/master/drivers/gpu/drm/radeon/radeon_dp_auxch.c > > Is the radeon one. 16 bytes are DP1.1, but later DP works better with more. The radeon hw engine just takes, request/address and data, then the hw sends it out for replies it just writes request/address and reads the data back from the hw. > > I think Intel i915 engine is quite similar https://github.com/torvalds/linux/blob/master/drivers/gpu/drm/i915/intel_dp.c#L999 > > I think you'd need the hw to do the aux encoding and tx/rx.