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22b10cdb73
MCC (multi-channel concurrency) related H2Cs (host to chip commands) require to wait for C2H (chip to host events) responses to judge the execution result and data. We introduce helpers to assist this process. Besides, we would like the helpers to be generic for use in driver even outside of MCC H2C/C2H, so we make a independent patch for them. In the following, I describe the things first. ``` (A) C2H is generated by FW, and then transferred upto driver. Hence, driver cannot get it immediately without a bit waitting/blocking. For this, we choose to use wait_for_completion_*() instead of busy polling. (B) From the driver management perspective, a scenario, e.g. MCC, may have mulitple kind of H2C functions requiring this process to wait for corresponding C2Hs. But, the driver management flow uses mutex to protect each behavior. So, one scenario triggers one H2C function at one time. To avoid rampant instances of struct completion for each H2C function, we choose to use one struct completion with one condition flag for one scenario. (C) C2Hs, which H2Cs will be waitting for, cannot be ordered with driver management flow, i.e. cannot enqueue work to the same ordered workqueue and cannot lock by the same mutex, to prevent H2C side from getting no C2H responses. So, those C2Hs are parsed in interrupt context directly as done in previous commit. (D) Following (C), the above underline H2Cs and C2Hs will be handled in different contexts without sync. So, we use atomic_cmpxchg() to compare and change the condition in atomic. ``` So, we introduce struct rtw89_wait_info which combines struct completion and atomic_t. Then, the below are the descriptions for helper functions. * rtw89_wait_for_cond() to wait for a completion based on a condition. * rtw89_complete_cond() to complete a given condition and carry data. Each rtw89_wait_info instance independently determines the meaning of its waitting conditions. But, RTW89_WAIT_COND_IDLE (UINT_MAX) is reserved. Signed-off-by: Zong-Zhe Yang <kevin_yang@realtek.com> Signed-off-by: Ping-Ke Shih <pkshih@realtek.com> Signed-off-by: Kalle Valo <kvalo@kernel.org> Link: https://lore.kernel.org/r/20221129083130.45708-4-pkshih@realtek.com |
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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.