forked from luck/tmp_suning_uos_patched
39afef8a28
commit cf9d052aa6005f1e8dfaf491d83bf37f368af69e upstream. In Linux, if a driver does disable_irq() and later does enable_irq() on its interrupt, I believe it's expecting these properties: * If an interrupt was pending when the driver disabled then it will still be pending after the driver re-enables. * If an edge-triggered interrupt comes in while an interrupt is disabled it should assert when the interrupt is re-enabled. If you think that the above sounds a lot like the disable_irq() and enable_irq() are supposed to be masking/unmasking the interrupt instead of disabling/enabling it then you've made an astute observation. Specifically when talking about interrupts, "mask" usually means to stop posting interrupts but keep tracking them and "disable" means to fully shut off interrupt detection. It's unfortunate that this is so confusing, but presumably this is all the way it is for historical reasons. Perhaps more confusing than the above is that, even though clients of IRQs themselves don't have a way to request mask/unmask vs. disable/enable calls, IRQ chips themselves can implement both. ...and yet more confusing is that if an IRQ chip implements disable/enable then they will be called when a client driver calls disable_irq() / enable_irq(). It does feel like some of the above could be cleared up. However, without any other core interrupt changes it should be clear that when an IRQ chip gets a request to "disable" an IRQ that it has to treat it like a mask of that IRQ. In any case, after that long interlude you can see that the "unmask and clear" can break things. Maulik tried to fix it so that we no longer did "unmask and clear" in commit |
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| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| 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.
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.