ca454bd42d
The Versatile Express uses a special configuration controller deeply embedded in the system motherboard FPGA to multiplex the two to three (!) display controller instances out to the single SiI9022 bridge. Set up an extra file with the logic to probe to the FPGA mux register on the system controller bus, then parse the device tree to see if there is a CLCD or HDLCD instance on the core tile (also known as the daughterboard) by looking in the root of the device tree for compatible nodes. - If there is a HDLCD on the core tile, and there is a driver for it, we exit probe and deactivate the motherboard CLCD. We do not touch the DVI mux in this case, to make sure we don't break HDLCD. - If there is a CLCD on both the motherboard and the core tile (only the CA9 has this) the core tile CLCD takes precedence and get muxed to the DVI connector. - Only if there is no working graphics on the core tile, the motherboard CLCD is probed and muxed to the DVI connector. Core tile graphics should always take precedence as it can address all memory and is also faster, however the motherboard CLCD is good to have around for diagnostics and testing. It is possible to test the motherboard CLCD by setting the status = "disabled" property on the core tile CLCD or HDLCD. Scale down the Versatile Express to 16BPP so we can support a 1024x768 display despite the bus bandwidth restrictions on this platform. (The motherboard CLCD supports slightly lower resolution.) Cc: Liviu Dudau <liviu.dudau@arm.com> Cc: Pawel Moll <pawel.moll@arm.com> Acked-by: Eric Anholt <eric@anholt.net> Tested-by: Robin Murphy <robin.murphy@arm.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org> Link: https://patchwork.freedesktop.org/patch/msgid/20180502134719.8388-1-linus.walleij@linaro.org |
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README
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.