9a81cc23df
When wcn36xx_dxe_tx_frame() is entered while the device is still processing the queue asyncronously, we are racing against the firmware code with updates to the buffer descriptors. Presumably, the firmware scans the ring buffer that holds the descriptors and scans for a valid control descriptor, and then assumes that the next descriptor contains the payload. If, however, the control descriptor is marked valid, but the payload descriptor isn't, the packet is not sent out. Another issue with the current code is that is lacks memory barriers before descriptors are marked valid. This is important because the CPU may reorder writes to memory, even if it is allocated as coherent DMA area, and hence the device may see incompletely written data. To fix this, the code in wcn36xx_dxe_tx_frame() was restructured a bit so that the payload descriptor is made valid before the control descriptor. Memory barriers are added to ensure coherency of shared memory areas. Signed-off-by: Daniel Mack <daniel@zonque.org> Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.