Fork of alistair23 Linux kernel for reMarkable from https://github.com/alistair23/linux
7232888366
Moving DMA configuration to happen later at driver probe time had the
unnoticed side-effect that we now perform DMA configuration for *every*
device represented in DT, rather than only those explicitly created by
the of_platform and PCI code.
As Christoph points out, this is not really the best thing to do. Whilst
there may well be other DMA-capable buses that can benefit from having
their children automatically configured after the bridge has probed,
there are also plenty of others like USB, MDIO, etc. that definitely do
not support DMA and should not be indiscriminately processed.
The good news is that in most cases the DT "dma-ranges" property serves
as an appropriate indicator - per a strict interpretation of the spec,
anything lacking a "dma-ranges" property should be considered not to
have a mapping of DMA address space from its children to its parent,
thus anything for which of_dma_get_range() does not succeed does not
need DMA configuration. Certain bus types have a general expectation of
DMA capability and carry a well-established precedent that an absent
"dma-ranges" implies the same as the empty property, so we automatically
opt those in to DMA configuration regardless, to avoid regressing most
existing platforms.
Fixes:
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|---|---|---|
| Documentation | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| 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.