1a3388d506
For a little over a year, U-Boot has configured the flow controller to perform automatic RAM re-repair on off->on power transitions of the CPU rail[1]. This is mandatory for correct operation of Tegra124. However, RAM re-repair relies on certain clocks, which the kernel must enable and leave running. PLLP is one of those clocks. This clock is shut down during LP1 in order to save power. Enable bypass (which I believe routes osc_div_clk, essentially the crystal clock, to the PLL output) so that this clock signal toggles even though the PLL is not active. This is required so that LP1 power mode (system suspend) operates correctly. The bypass configuration must then be undone when resuming from LP1, so that all peripheral clocks run at the expected rate. Without this, many peripherals won't work correctly; for example, the UART baud rate would be incorrect. NVIDIA's downstream kernel code only does this if not compiled for Tegra30, so the added code is made conditional upon the chip ID. NVIDIA's downstream code makes this change conditional upon the active CPU cluster. The upstream kernel currently doesn't support cluster switching, so this patch doesn't test the active CPU cluster ID. [1] 3cc7942a4ae5 ARM: tegra: implement RAM repair Reported-by: Jonathan Hunter <jonathanh@nvidia.com> Cc: stable@vger.kernel.org Signed-off-by: Stephen Warren <swarren@nvidia.com> Signed-off-by: Thierry Reding <treding@nvidia.com> |
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| arch | ||
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| drivers | ||
| fs | ||
| include | ||
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| ipc | ||
| kernel | ||
| lib | ||
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| samples | ||
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| security | ||
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| tools | ||
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| .cocciconfig | ||
| .get_maintainer.ignore | ||
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| Kbuild | ||
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| README | ||
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.