The HSM clock needs to be setup at around 101% of the pixel rate. This was done previously by setting the clock rate to 163.7MHz at probe time and only check in mode_valid whether the mode pixel clock was under the pixel clock +1% or not. However, with 4k we need to change that frequency to a higher frequency than 163.7MHz, and yet want to have the lowest clock as possible to have a decent power saving. Let's change that logic a bit by setting the clock rate of the HSM clock to the pixel rate at encoder_enable time. This would work for the BCM2711 that support 4k resolutions and has a clock that can provide it, but we still have to take care of a 4k panel plugged on a BCM283x SoCs that wouldn't be able to use those modes, so let's define the limit in the variant. Signed-off-by: Maxime Ripard <maxime@cerno.tech> Tested-by: Chanwoo Choi <cw00.choi@samsung.com> Tested-by: Hoegeun Kwon <hoegeun.kwon@samsung.com> Tested-by: Stefan Wahren <stefan.wahren@i2se.com> Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com> Link: https://patchwork.freedesktop.org/patch/msgid/7e692ddc231d33dd671e70ea04dd1dcf56c1ecb3.1599120059.git-series.maxime@cerno.tech
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.
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