On 2025-10-17 20:40, Tom Rini wrote:
On Fri, Oct 17, 2025 at 08:49:47PM +0530, Kaustabh Chakraborty wrote:
In devices where the U-Boot is used as a secondary bootloader, we rely
on the device's primary bootloader to implement CNTFRQ_EL0. However,
this reliance may lead to a non-functional timer in broken firmware.
For instance, some versions of Samsung's S-Boot don't implement it.
It's
also not possible to set it in the U-Boot, because it's booted in a
lower
exception level. CNTFRQ_EL0 is reported to be 0.
Use gd->arch.timer_rate_hz to override the queried value if set. This
setting needs to be done in the board file, preferrably in
timer_init().
Signed-off-by: Kaustabh Chakraborty <[email protected]>
---
Changes in v2:
- Switched to using gd->arch.timer_rate_hz instead of a new config
option (Ahmad Fatoum)
- Link to v1:
https://lore.kernel.org/r/[email protected]
---
arch/arm/cpu/armv8/generic_timer.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/arch/arm/cpu/armv8/generic_timer.c
b/arch/arm/cpu/armv8/generic_timer.c
index
1de7ec596fc7cbbc3e78a241f163bc0a4fcad6b6..1bc72ed26ca31af8e8e72008ed7885cbde23b076
100644
--- a/arch/arm/cpu/armv8/generic_timer.c
+++ b/arch/arm/cpu/armv8/generic_timer.c
@@ -19,6 +19,10 @@ DECLARE_GLOBAL_DATA_PTR;
unsigned long notrace get_tbclk(void)
{
unsigned long cntfrq;
+
+ if (gd->arch.timer_rate_hz)
+ return gd->arch.timer_rate_hz;
+
asm volatile("mrs %0, cntfrq_el0" : "=r" (cntfrq));
return cntfrq;
}
This would impact coreprimevelte (as it's the only ARM64 platform to
set
gd->arch.timer_rate_hz) but as it's also a Samsung platform it's likely
in the same broken situation your platforms are.
I guess coreprimevelte is a a bit too old to have that issue. Either
way,
it would be fine as the frequency is set to 26MHz [1], which is the
timer
frequency of that device [2].
[1]
https://elixir.bootlin.com/u-boot/v2025.10/source/arch/arm/mach-mmp/board.c#L31
[2]
https://github.com/LegoLivesMatter/android_kernel_samsung_coreprimevelte/blob/android-5.1/arch/arm64/boot/dts/pxa1908.dtsi#L91
--
Tom
