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.
This patch also fixes a potential problem with vfp_pm_suspend(), where
VFP context can be lost if the current process does not have VFP enabled.
Fixed by calling vfp_pm_save_context().
Signed-off-by: Tero Kristo <tero.kristo@xxxxxxxxx>
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 | 28 ++++++++++++++++++++--------
1 files changed, 20 insertions(+), 8 deletions(-)
diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
index 2d7423a..920a33b 100644
--- a/arch/arm/vfp/vfpmodule.c
+++ b/arch/arm/vfp/vfpmodule.c
@@ -329,22 +329,34 @@ static void vfp_enable(void *unused)
#ifdef CONFIG_PM
#include <linux/sysdev.h>
-static int vfp_pm_suspend(struct sys_device *dev, pm_message_t state)
+void vfp_pm_save_context(void)
{
- struct thread_info *ti = current_thread_info();
u32 fpexc = fmrx(FPEXC);
+ unsigned int cpu = get_cpu();
+
+ /* Save last_VFP_context if needed */
+ if (last_VFP_context[cpu]) {
+ /* Enable vfp to save context */
+ if (!(fpexc & FPEXC_EN)) {
+ vfp_enable(NULL);
+ fmxr(FPEXC, fpexc | FPEXC_EN);
+ }
- /* if vfp is on, then save state for resumption */
- if (fpexc & FPEXC_EN) {
printk(KERN_DEBUG "%s: saving vfp state\n", __func__);
- vfp_save_state(&ti->vfpstate, fpexc);
+ vfp_save_state(last_VFP_context[cpu], fpexc);
/* disable, just in case */
- fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN);
+ fmxr(FPEXC, fpexc & ~FPEXC_EN);
+
+ last_VFP_context[cpu] = NULL;
}
- /* clear any information we had about last context state */
- memset(last_VFP_context, 0, sizeof(last_VFP_context));
+ put_cpu();
+}
+
+static int vfp_pm_suspend(struct sys_device *dev, pm_message_t state)
+{
+ vfp_pm_save_context();
return 0;
}
--
1.5.4.3
--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
