Some of the functions (like cdn_dp_dpcd_read, cdn_dp_get_edid_block) allow to read 64KiB, but the cdn_dp_mailbox_read_receive, that is used by them, can read only up to 255 bytes at once. Normally, it's not a big issue as DPCD or EDID reads won't (hopefully) exceed that value. The real issue here is the revocation list read during the HDCP authentication process. (problematic use case: https://chromium.googlesource.com/chromiumos/third_party/kernel/+/chromeos-4.4/drivers/gpu/drm/rockchip/cdn-dp-reg.c#1152) The list can reach 127*5+4 bytes (num devs * 5 bytes per ID/Bksv + 4 bytes of an additional info). In other words - CTSes with HDCP Repeater won't pass without this fix. Oh, and the driver will most likely stop working (best case scenario). Signed-off-by: Damian Kos <dkos@cadence.com> Signed-off-by: Heiko Stuebner <heiko@sntech.de> Link: https://patchwork.freedesktop.org/patch/msgid/1541518625-25984-1-git-send-email-dkos@cadence.com
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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