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Our current limited range matrix is a bit off. I think it was originally calculated with rounding, as if we wanted the normal pixel replication type of behaviour. That is, since the 8bpc max value is 0xeb we assumed the 16bpc max value should be 0xebeb, but what the HDMI spec actually says it should be is 0xeb00. So to get what we want we make the formula out = in * (235-16) << (12-8) / in_max + 16 << (12-8), with 12 being precision of the csc, 8 being the precision of the constants we used. The hardware takes its coefficients as floating point values, but the (235−16)/255 = ~.86, so exponent 0 is what we want anyway, so it works out perfectly without having to hardcode it in hex or start playing with floats. In terms of raw numbers we are feeding the hardware the post offset changes from 0x101 to 0x100, and the coefficient changes from 0xdc0 to 0xdb0 (~.860->~.855). So this should make everything come out just a tad darker. I already used better constants in lut_limited_range() earlier so the output of the two paths should be closer now. Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20230329135002.3096-2-ville.syrjala@linux.intel.com Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com> |
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| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
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| security | ||
| sound | ||
| tools | ||
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| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
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| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.