Eric Anholt at Broadcom who is known for his work on developing the VC4 open-source graphics driver stack for the Raspberry Pi on Linux has also been acting as the kernel maintainer for all things Pi.
Today on his blog Anholt wrote, "I spent most of [the month] working on the Raspberry Pi 3 support so I could have a working branch for upstream day 1. That involved cleaning up the SDHOST driver for submission, cleaning up pinctrl DT, writing an I2C GPIO expander driver, debugging the I2C controller, fixing HDMI hotplug handling, debugging EMMC (not quite done!), scraping together some wireless firmware, and a bunch of work trying to get BT working on the UART. I'm happy to say that on day 1 I published a branch that worked the same as a RPi2, and by the end of the day I had wireless working. Some of the patches are now out for review, and I'll be working on cleaning up the rest in the near future." (As mentioned earlier, on the graphics side, getting the RPi3 working with the VC4 graphics driver requires just a few fixes.)
Eric also noted in today's blog post he has been working on getting some display panel working with his VC4 driver. Unfortunately, he doesn't have the official 7-inch DSI touch-screen working with his driver as he is running into DSI (Display Serial Interface) problems. However, he is having luck with a DPI panel using the Adafruit Kippah and will have patches for that support soon.