mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-05-05 21:44:23 -04:00
95fd3ad9cd
In addition to the base, low and high clock configuration, the AC timing register #1 on the AST2400 houses fields controlling: 1. tBUF: Minimum delay between Stop and Start conditions 2. tHDSTA: Hold time for the Start condition 3. tACST: Setup time for Start and Stop conditions, and hold time for the Repeated Start condition These values are defined in hardware on the AST2500 and therefore don't need to be set. aspeed_i2c_init_clk() was performing a direct write of the generated clock values rather than a read/mask/modify/update sequence to retain tBUF, tHDSTA and tACST, and therefore cleared the tBUF, tHDSTA and tACST fields on the AST2400. This resulted in a delay/setup/hold time of 1 base clock, which in some configurations is not enough for some devices (e.g. the MAX31785 fan controller, with an APB of 48MHz and a desired bus speed of 100kHz). Signed-off-by: Andrew Jeffery <andrew@aj.id.au> Reviewed-by: Brendan Higgins <brendanhiggins@google.com> Tested-by: Brendan Higgins <brendanhiggins@google.com> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
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.