ARM: tegra: Initialize r0 register for firmware wake-up

Downstream kernel of ASUS TF300T sets r0 to #3. Unfortunately there is no explanation in downstream code whether this is really needed. Some of T30 downstream kernels have and explicit comment that all arguments are ignored by firmware. Let's take the safe side and replicate behaviour of the TF300T downstream kernel. Tested-by: Peter Geis <[email protected]> Signed-off-by: Dmitry Osipenko <[email protected]>
okias · Mar 19, 2020 · 70372c8 · 70372c8
1 parent 8f9f49f
commit 70372c8
Showing 1 changed file with 6 additions and 1 deletion.
diff --git a/arch/arm/mach-tegra/reset-handler.S b/arch/arm/mach-tegra/reset-handler.S
@@ -98,7 +98,12 @@ ENTRY(tegra_resume_trusted_foundations)
  reteq lr
 
  .arch_extension sec
- /* First call after suspend wakes firmware. No arguments required. */
+ /*
+ * First call after suspend wakes firmware. No arguments required
+ * for some firmware versions. Downstream kernel of ASUS TF300T uses
+ * r0=3 for the wake-up notification.
+ */
+ mov r0, #3
  smc #0
 
  b cpu_resume