From: Tero Kristo <tero.kristo@xxxxxxxxx>
In some ARM architectures, like OMAP3, the VFP context can be lost during
dynamic sleep cycle. For this purpose, there is now a function
vfp_pm_save_context() that should be called before the VFP is assumed to
lose context. Next VFP trap will then restore context automatically.
We need to have the last_VFP_context[cpu] cleared after the save in idle,
else the restore would fail to restore when it sees that the last_VFP_context
is same as the current threads vfp_state. This happens when the same
process/thread traps an exception post idle.
Main work for this patch was done by Peter and Rajendra. Some cleanup and
optimization by Tero.
Signed-off-by: Tero Kristo <tero.kristo@xxxxxxxxx>
Acked-by: Tony Lindgren <tony@xxxxxxxxxxx>
Cc: Vishwanath Sripathy <vishwanath.bs@xxxxxx>
Cc: Rajendra Nayak <rnayak@xxxxxx>
Cc: Richard Woodruff <r-woodruff2@xxxxxx>
Cc: Peter 'p2' De Schrijver <peter.de-schrijver@xxxxxxxxx>
---
arch/arm/vfp/vfpmodule.c | 25 +++++++++++++++++++++++++
1 files changed, 25 insertions(+), 0 deletions(-)
diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
index 2d7423a..80a08bd 100644
--- a/arch/arm/vfp/vfpmodule.c
+++ b/arch/arm/vfp/vfpmodule.c
@@ -329,6 +329,31 @@ static void vfp_enable(void *unused)
#ifdef CONFIG_PM
#include <linux/sysdev.h>
+void vfp_pm_save_context(void)
+{
+ struct thread_info *thread = current_thread_info();
+ u32 fpexc = fmrx(FPEXC);
+ __u32 cpu = thread->cpu;
+
+ if (last_VFP_context[cpu]) {
+ if (!(fpexc & FPEXC_EN)) {
+ /* enable vfp now to save context */
+ vfp_enable(NULL);
+ fmxr(FPEXC, fmrx(FPEXC) | FPEXC_EN);
+ }
+ vfp_save_state(last_VFP_context[cpu], fpexc);
+
+ /* Disable vfp. The next inst traps an exception and restores*/
+ fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN);
+
+ /*
+ * This is needed else the restore might fail if it sees
+ * last_VFP_context if same as the current threads vfp_state.
+ */
+ last_VFP_context[cpu] = NULL;
+ }
+}
+
static int vfp_pm_suspend(struct sys_device *dev, pm_message_t state)
{
struct thread_info *ti = current_thread_info();
--
1.5.4.3
--
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