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Steven Price
a53f2c035e
drm/panfrost: Calculate lock region size correctly
It turns out that when locking a region, the region must be a naturally aligned power of 2. The upshot of this is that if the desired region crosses a 'large boundary' the region size must be increased significantly to ensure that the locked region completely covers the desired region. Previous calculations (including in kbase for the proprietary driver) failed to take this into account. Since it's known that the lock region must be naturally aligned we can compute the required size by looking at the highest bit position which changes between the start/end of the lock region (subtracting 1 from the end because the end address is exclusive). The start address is then aligned based on the size (this is technically unnecessary as the hardware will ignore these bits, but the spec advises to do this "to avoid confusion"). Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com> Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com> Signed-off-by: Steven Price <steven.price@arm.com> Link: https://patchwork.freedesktop.org/patch/msgid/20210903094957.74560-1-steven.price@arm.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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