33e39350eb
Immediate data transfers (IDT) allow the HCD to copy small chunks of data (up to 8bytes) directly into its output transfer TRBs. This avoids the somewhat expensive DMA mappings that are performed by default on most URBs submissions. In the case an URB was suitable for IDT. The data is directly copied into the "Data Buffer Pointer" region of the TRB and the IDT flag is set. Instead of triggering memory accesses the HC will use the data directly. The implementation could cover all kind of output endpoints. Yet Isochronous endpoints are bypassed as I was unable to find one that matched IDT's constraints. As we try to bypass the default DMA mappings on URB buffers we'd need to find a Isochronous device with an urb->transfer_buffer_length <= 8 bytes. The implementation takes into account that the 8 byte buffers provided by the URB will never cross a 64KB boundary. Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de> Reviewed-by: Felipe Balbi <felipe.balbi@linux.intel.com> Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
README
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.