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Convert multiple full duplex transfers in to a single transfer to reduce CPU load. Current driver version support following filtering modes: - ads7846_no_filter() - not filtered - ads7846_debounce_filter() - driver specific debounce filter - pdata->filter - platform specific debounce filter (do any platform provides such filter?) Without filter this HW is not really usable, since the physic of resistive touchscreen can provide some bounce effects. With driver internal filter, we have constant amount of retries + debounce retries if some anomaly was detected. High amount of tiny SPI transfers is the primer reason of high CPU load and interrupt frequency. This patch create one SPI transfer with all fields and not optional retires. If bounce anomaly was detected, we will make more transfer if needed. Without this patch, we will get about 10% CPU load on iMX6S on pen-down event. For example by holding stylus on the screen. With this patch, depending in the amount of retries, the CPU load will be 1% with "ti,debounce-rep = <3>". One buffer transfer allows us to use PIO FIFO or DMA engine, depending on the platform. Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de> Link: https://lore.kernel.org/r/20201110085041.16303-3-o.rempel@pengutronix.de Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> |
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| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
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| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
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| 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.