| Message ID | 20171211075001.6100-5-mylene.josserand@free-electrons.com |
|---|---|
| State | New |
| Headers | show |
| Series | Sunxi: Add SMP support on A83T | expand |
Hi, On Mon, Dec 11, 2017 at 08:50:01AM +0100, Mylène Josserand wrote: > By default, virtual timers are used. These timers need an offset > that must be set by firmware, for example. In case of SMP support, > after a reset, this offset is in "unknown" state and produced > a hang of the kernel. > > Use "arm,cpu-registers-not-fw-configured" property allows to use > physical timers instead of virtual ones. > > Signed-off-by: Mylène Josserand <mylene.josserand@free-electrons.com> Your commit log could be a little better, something like: " The ARM architected timers use an offset between their physical and virtual counters. That offset should be configured by the bootloader in CNTVOFF. However, the A83t bootloader fails to do so, and we end up with an undefined offset (which in our case is random), meaning that each CPU will have a different time, which isn't working very well. Fix that by setting the arm,cpu-registers-not-fw-configured that will make Linux use the physical timers instead of the virtual ones. One possible side effect would be that the virtualization features would be disabled. However, due to the way the GIC has been integrated in the system, it is already unusable so we're effectively not losing any feature. " The commit title should be improved too. Maxime
diff --git a/arch/arm/boot/dts/sun8i-a83t.dtsi b/arch/arm/boot/dts/sun8i-a83t.dtsi index 3e2aad537972..0fe4b9e5dee1 100644 --- a/arch/arm/boot/dts/sun8i-a83t.dtsi +++ b/arch/arm/boot/dts/sun8i-a83t.dtsi @@ -121,6 +121,7 @@ <GIC_PPI 14 (GIC_CPU_MASK_SIMPLE(8) | IRQ_TYPE_LEVEL_LOW)>, <GIC_PPI 11 (GIC_CPU_MASK_SIMPLE(8) | IRQ_TYPE_LEVEL_LOW)>, <GIC_PPI 10 (GIC_CPU_MASK_SIMPLE(8) | IRQ_TYPE_LEVEL_LOW)>; + arm,cpu-registers-not-fw-configured; }; clocks {
By default, virtual timers are used. These timers need an offset that must be set by firmware, for example. In case of SMP support, after a reset, this offset is in "unknown" state and produced a hang of the kernel. Use "arm,cpu-registers-not-fw-configured" property allows to use physical timers instead of virtual ones. Signed-off-by: Mylène Josserand <mylene.josserand@free-electrons.com> --- arch/arm/boot/dts/sun8i-a83t.dtsi | 1 + 1 file changed, 1 insertion(+)