726df1d5a6
It seems that SD3.0 advertisement needs to be set for higher eMMC speed modes (namely DDR52) as well. The TRM states that the SD3.0 advertisement bit should be set for all controller instances, even for those not supporting UHS-I mode... When specifying vqmmc-supply as a fixed 1.8V regulator on a Tegra SD/MMC instance which is connected to a eMMC device, the stack enables SD3.0. However, enabling it has consequences: If SDHCI 3.0 support is advertised the stack enables Auto-CMD23. Unfortunately Auto-CMD23 seems not to work well with Tegra 3 currently. It leads to regular warnings: mmc2: Got command interrupt 0x00010000 even though no command operation was in progress. It is not entirely clear why those errors happens. It seems that a Linux 3.1 based downstream kernel which has Auto-CMD23 support does not show those warnings. Use quirk SDHCI_QUIRK2_ACMD23_BROKEN to prevent Auto-CMD23 being used for now. With this the eMMC works stable on high-speed mode while still announcing SD3.0. This allows to use mmc-ddr-1_8v to enables DDR52 mode. In DDR52 mode read speed improves from about 42MiB/s to 72MiB/s on an Apalis T30. Signed-off-by: Stefan Agner <stefan@agner.ch> Tested-by: Marcel Ziswiler <marcel.ziswiler@toradex.com> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> |
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| 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 | ||
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.