d584b65c0d
The transmit register supports batched writes. The key is simply to keep sending additional bytes up to the FIFO size in the same SPI transaction with the CS pin still being held low. This duplicates the regmap infrastructure to a certain extent. There are some provisions for multiple writes in there, but there does not appear to be any support for those writes which are destined to the *same* register (and also no standard for SPI bus transfers of these, anyway). This patch does not solve every case (if the UART xmit circular buffer wraps around, we're still doing two SPI transactions), but at least it's not one-byte-per-transaction anymore. This change does not touch the receive path at this time. Doing that in the generic case appears to be impossible in the general case, because the chips' status register contains data about the *current* byte in the HW's Rx FIFO. We cannot read these two registers in one go, unfortunately. Signed-off-by: Jan Kundrát <jan.kundrat@cesnet.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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| drivers | ||
| firmware | ||
| fs | ||
| include | ||
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| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
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| tools | ||
| usr | ||
| virt | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
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| README | ||
README
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.