Mateusz Jończyk 69d05f0a4b drm/radeon: avoid bogus "vram limit (0) must be a power of 2" warning
[ Upstream commit 9da2902609f7519c48eda84f953f72fee53f2b71 ]

I was getting the following message on boot on Linux 5.19-rc5:
        radeon 0000:01:05.0: vram limit (0) must be a power of 2
(I didn't use any radeon.vramlimit commandline parameter).

This is caused by
commit 8c2d34eb53b9 ("drm/radeon: use kernel is_power_of_2 rather than local version")
which removed radeon_check_pot_argument() and converted its users to
is_power_of_2(). The two functions differ in its handling of 0, which is
the default value of radeon_vram_limit: radeon_check_pot_argument()
"incorrectly" considered it a power of 2, while is_power_of_2() does not.

An appropriate conditional silences the warning message.

It is not necessary to add a similar test to other callers of
is_power_of_2() in radeon_device.c. The matching commit in amdgpu:
commit 761175078466 ("drm/amdgpu: use kernel is_power_of_2 rather than local version")
is unaffected by this bug.

Tested on Radeon HD 3200.

Not ccing stable, this is not serious enough.

Fixes: 8c2d34eb53b9 ("drm/radeon: use kernel is_power_of_2 rather than local version")
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: "Pan, Xinhui" <Xinhui.Pan@amd.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Jonathan Gray <jsg@jsg.id.au>
Signed-off-by: Mateusz Jończyk <mat.jonczyk@o2.pl>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-08-17 15:14:42 +02:00
2022-07-27 09:43:07 -07:00
2022-08-17 15:14:20 +02:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
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Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
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    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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