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d385c16173
To get refresh rate as vblank timer period and keep the precision, the
calculation of rate is multiplied by 1000. However old logic was using:
rate = pixel clock / (h * v / 1000). When the h/v total is invalid, like
all 0, h * v / 1000 will be rounded to 0, which leads to a divided by 0
fault.
0 H/V are already checked above. Instead of divide after divide, refine
the calculation to divide after multiply: "pixel clock * 1000 / (h * v)"
Guest driver should guarantee the correctness of the timing regs' value.
Fixes: 6a4500c7b8 ("drm/i915/gvt: Get accurate vGPU virtual display refresh rate from vreg")
Reported-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Colin Xu <colin.xu@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20210416083355.159305-1-colin.xu@intel.com
Reviewed-by: Zhenyu Wang <zhenyuw@linux.intel.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.