| Message ID | 20190113021719.46457-1-samuel@sholland.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | Allwinner A64 timer workaround | expand |
On 13/01/2019 03:17, Samuel Holland wrote: > This is the third version of a patch series to fix system clock jumps > and other timer instability on the Allwinner A64 SoC. It has now been > tested for a week, and I've received no reports of date jumps with this > version. So this is, as far as I can tell, a complete workaround. > > See the commit messages for a detailed description of the issue, but the > summary is that, when a high counter bit rolls over, indeterminance in > the low bits causes CNTPCT/CNTVCT and their respective TVAL registers to > jump forward or backward. Backward jumps (or the next read after forward > jumps) are sometimes seen by the kernel and interpreted as the timer > wrapping around after 2^56 cycles. This causes the system clock to jump > forward approximately 91 years. > > changes since v2; > - Reduced workaround threshold from 11 to 10 bits based on reports from > other hardare and the U-Boot version of this workaround > - Added TVAL handling based on Marc's suggestion > - Added erratum documentation and renamed symbols to match > - Added Maxime's Acked-by > > changes since v1: > - Add an iteration limit like most other arch timer workarounds > - Added Andre's Tested-by > > Samuel Holland (2): > arm64: arch_timer: Workaround for Allwinner A64 timer instability > arm64: dts: allwinner: a64: Enable A64 timer workaround > > Documentation/arm64/silicon-errata.txt | 2 + > arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi | 1 + > drivers/clocksource/Kconfig | 10 ++++ > drivers/clocksource/arm_arch_timer.c | 55 +++++++++++++++++++ > 4 files changed, 68 insertions(+) > Applied. Took the opportunity to add the stable@ tag. Thanks -- Daniel
On Mon, Jan 14, 2019 at 8:57 PM Daniel Lezcano <daniel.lezcano@linaro.org> wrote: > > On 13/01/2019 03:17, Samuel Holland wrote: > > This is the third version of a patch series to fix system clock jumps > > and other timer instability on the Allwinner A64 SoC. It has now been > > tested for a week, and I've received no reports of date jumps with this > > version. So this is, as far as I can tell, a complete workaround. > > > > See the commit messages for a detailed description of the issue, but the > > summary is that, when a high counter bit rolls over, indeterminance in > > the low bits causes CNTPCT/CNTVCT and their respective TVAL registers to > > jump forward or backward. Backward jumps (or the next read after forward > > jumps) are sometimes seen by the kernel and interpreted as the timer > > wrapping around after 2^56 cycles. This causes the system clock to jump > > forward approximately 91 years. > > > > changes since v2; > > - Reduced workaround threshold from 11 to 10 bits based on reports from > > other hardare and the U-Boot version of this workaround > > - Added TVAL handling based on Marc's suggestion > > - Added erratum documentation and renamed symbols to match > > - Added Maxime's Acked-by > > > > changes since v1: > > - Add an iteration limit like most other arch timer workarounds > > - Added Andre's Tested-by > > > > Samuel Holland (2): > > arm64: arch_timer: Workaround for Allwinner A64 timer instability > > arm64: dts: allwinner: a64: Enable A64 timer workaround > > > > Documentation/arm64/silicon-errata.txt | 2 + > > arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi | 1 + > > drivers/clocksource/Kconfig | 10 ++++ > > drivers/clocksource/arm_arch_timer.c | 55 +++++++++++++++++++ > > 4 files changed, 68 insertions(+) > > > > Applied. Took the opportunity to add the stable@ tag. Not seeing it in tip just yet. Was it applied for -rc or -next? Need to know which branch to apply the device tree patch to. Thanks ChenYu