Paul Cercueil
f4c255f1a7
dmaengine: dma-jz4780: Break descriptor chains on JZ4740
The current driver works perfectly fine on every generation of the JZ47xx SoCs, except on the JZ4740. There, when hardware descriptors are chained together (with the LINK bit set), the next descriptor isn't automatically fetched as it should - instead, an interrupt is raised, even if the TIE bit (Transfer Interrupt Enable) bit is cleared. When it happens, the DMA transfer seems to be stopped (it doesn't chain), and it's uncertain how many bytes have actually been transferred. Until somebody smarter than me can figure out how to make chained descriptors work on the JZ4740, we now disable chained descriptors on that particular SoC. Signed-off-by: Paul Cercueil <paul@crapouillou.net> Link: https://lore.kernel.org/r/20190714215504.10877-1-paul@crapouillou.net Signed-off-by: Vinod Koul <vkoul@kernel.org>
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.
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