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It appears that there is a typo in the rk3288 TRM. For GRF_SOC_CON0[7] it says that 0 means "vepu" and 1 means "vdpu". It's the other way around. How do I know? Here's my evidence: 1. Prior to commit4d3e84f996("clk: rockchip: describe aclk_vcodec using the new muxgrf type on rk3288") we always pretended that we were using "aclk_vdpu" and the comment in the code said that this matched the default setting in the system. In fact the default setting is 0 according to the TRM and according to reading memory at bootup. In addition rk3288-based Chromebooks ran like this and the video codecs worked. 2. With the existing clock code if you boot up and try to enable the new VIDEO_ROCKCHIP_VPU as a module (and without "clk_ignore_unused" on the command line), you get errors like "failed to get ack on domain 'pd_video', val=0x80208". After flipping vepu/vdpu things init OK. 3. If I export and add both the vepu and vdpu to the list of clocks for RK3288_PD_VIDEO I can get past the power domain errors, but now I freeze when the vpu_mmu gets initted. 4. If I just mark the "vdpu" as IGNORE_UNUSED then everything boots up and probes OK showing that somehow the "vdpu" was important to keep enabled. This is because we were actually using it as a parent. 5. After this change I can hack "aclk_vcodec_pre" to parent from "aclk_vepu" using assigned-clocks and the video codec still probes OK. 6. Rockchip has said so on the mailing list [1]. ...so let's fix it. Let's also add CLK_SET_RATE_PARENT to "aclk_vcodec_pre" as suggested by Jonas Karlman. Prior to the same commit you could do clk_set_rate() on "aclk_vcodec" and it would change "aclk_vdpu". That's because "aclk_vcodec" was a simple gate clock (always gets CLK_SET_RATE_PARENT) and its direct parent was "aclk_vdpu". After that commit "aclk_vcodec_pre" gets in the way so we need to add CLK_SET_RATE_PARENT to it too. [1] https://lkml.kernel.org/r/1d17b015-9e17-34b9-baf8-c285dc1957aa@rock-chips.com Fixes:4d3e84f996("clk: rockchip: describe aclk_vcodec using the new muxgrf type on rk3288") Suggested-by: Jonas Karlman <jonas@kwiboo.se> Suggested-by: Randy Li <ayaka@soulik.info> Signed-off-by: Douglas Anderson <dianders@chromium.org> Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
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.