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

Downstream kernel of ASUS TF300T sets r0 to #3. There is no explanation in downstream code whether this is really needed and some of T30 downstream kernels have and explicit comment telling that all arguments are ignored by firmware. Let's take a safe side by replicating behavior of the TF300T downstream kernel. This change works fine on Ouya and Nexus 7 devices. Tested-by: Michał Mirosław <[email protected]> Tested-by: Jasper Korten <[email protected]> Tested-by: David Heidelberg <[email protected]> Tested-by: Peter Geis <[email protected]> Signed-off-by: Dmitry Osipenko <[email protected]>
okias · May 4, 2020 · f56df33 · f56df33
1 parent d6d360f
commit f56df33
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