acdc8e71d9
On the Amlogic G12A SoC family, (only) the SDIO controller fails to access the data from DRAM, leading to a broken controller. But each MMC controller has 1,5KiB of SRAM after the registers, that can be used as bounce buffer to avoid direct DRAM access from the integrated DMAs (this SRAM may be used by the boot ROM when DRAM is not yet initialized). The quirk is to disable the chained descriptor for this controller, and use this SRAM memory zone as buffer for the bounce buffer fallback mode. The performance hit hasn't been evaluated, but the fix has been tested using a WiFi AP6398S SDIO module, and the iperf3 Bandwidth measurement gave 55.2 Mbits/sec over a 63 Hours long test, with the SDIO ios set as High-Speed at 50MHz clock. It gave 170 Mbits/sec as SDR104 and 200MHz clock. Reviewed-by: Kevin Hilman <khilman@baylibre.com> Tested-by: Guillaume La Roque <glaroque@baylibre.com> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> |
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| Documentation | ||
| 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.