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22000 devices (previously referenced as A000) can support short transmit queues. This means that we have less DMA descriptors (TFD) for those shorter queues. Previous devices must still have 256 TFDs for each queue even if those 256 TFDs point to fewer buffers. When I introduced support for the short queues for 22000 I broke older devices by assuming that they can also have less TFDs in their queues. This led to several problems: 1) the payload of the commands weren't unmapped properly which caused the SWIOTLB to complain at some point. 2) the hardware could get confused and we get hardware crashes. The corresponding bugzilla entries are: https://bugzilla.kernel.org/show_bug.cgi?id=198201 https://bugzilla.kernel.org/show_bug.cgi?id=198265 Cc: stable@vger.kernel.org # 4.14+ Fixes: 4ecab5616023 ("iwlwifi: pcie: support short Tx queues for A000 device family") Reviewed-by: Sharon, Sara <sara.sharon@intel.com> Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com> Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. 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.