On Fri, Nov 28, 2014 at 02:35:32PM +0000, Mark Rutland wrote:

On Fri, Nov 28, 2014 at 02:29:13PM +0000, Catalin Marinas wrote:

quoted

On Thu, Nov 27, 2014 at 01:43:09PM +0000, Mark Rutland wrote:

quoted

On Thu, Nov 27, 2014 at 12:12:15PM +0000, Catalin Marinas wrote:

quoted

On Thu, Nov 27, 2014 at 11:50:43AM +0000, Mark Rutland wrote:

quoted

On Tue, Nov 25, 2014 at 12:16:56PM +0000, Chunyan Zhang wrote:

quoted

+
+       timer {
+               compatible = "arm,armv8-timer";
+               interrupts = <1 13 0xff01>,
+                            <1 14 0xff01>,
+                            <1 11 0xff01>,
+                            <1 10 0xff01>;
+               clock-frequency = <26000000>;

Please remove the clock-frequency property. Your FW should initialise
CNTFRQ_EL0 on all CPUs (certainly PSCI 0.2 requires that you do this).

Since this comes up regularly, I think we need a dev_warn() in the arch
timer driver when CONFIG_ARM64.

I'll ack such a patch ;)

How rude would this be?

diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 2133f9d59d06..aaaf3433ccb9 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c

@@ -371,7 +371,8 @@ arch_timer_detect_rate(void __iomem *cntbase, struct device_node *np)

		return;
 
	/* Try to determine the frequency from the device tree or CNTFRQ */
-	if (of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) {
+	if (IS_ENABLED(CONFIG_ARM64) ||
+	    of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) {
		if (cntbase)
			arch_timer_rate = readl_relaxed(cntbase + CNTFRQ);
		else

Probably too rude, given it doesn't WARN() the user.

We override broken hardware ID registers all the time in device-tree without
dumping stack. Why is this any different?

We should be extremely loud if we see the clock-frequency property on an
arm64 system. Whether or not we should ignore the property is another
matter.

I don't really see the point in ignoring it. We will see broken hardware
[1] and this is just preventing ourselves from working around it. I'd much
rather have arch-timers with a "clock-frequence" property than have some
other timer instead because the kernel driver is being stubborn.

Will

[1] A previous version of the Juno firmware, for example.