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The controller provides trace FIFO DFX tool to assist link fault debugging and link optimization. This tool can be helpful when debugging link faults without SAS analyzers. Each PHY has an independent trace FIFO interface. The user can configure the trace FIFO tool of one PHY by using the following six interfaces: signal_sel: select signal group applies to different scenarios. 0x0: linkrate negotiation 0x1: Host 12G TX train 0x2: Disk 12G TX train 0x3: SAS PHY CTRL DFX 0 0x4: SAS PHY CTRL DFX 1 0x5: SAS PCS DFX other: linkrate negotiation dump_mask: The masked hardware status bit will not be updated. dump_mode: determines how to dump data after trigger signal is generated. 0x0: dump forever 0x1: dump 32 data after trigger signal is generated 0x2: no more dump after trigger signal is generated trigger_mode: determines the trigger mode, level or edge. 0x0: dump when trigger signal changed 0x1: dump when trigger signal's level equal to trigger_level 0x2: dump when trigger signal's level different from trigger_level trigger_level: determines the trigger level. trigger_msk: mask trigger signal The user can get 32-byte values from hardware by reading the rd_data. These values consitute the status record of the hardware at different time points. Link: https://lore.kernel.org/r/1611659068-131975-6-git-send-email-john.garry@huawei.com Signed-off-by: Luo Jiaxing <luojiaxing@huawei.com> Signed-off-by: John Garry <john.garry@huawei.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
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.