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hwc: Support VSYNC notification via sysfs

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* Poll on FB0 sysfs for VSYNC events. This requires kernel support to
   call sysfs_notify instead of sending a uevent.

Change-Id: I48734d8ffdd59dc1de7064fa004af1332ceb7623
This commit is contained in:
Steve Kondik 2012-09-25 17:29:38 -07:00 committed by Andrew Sutherland
parent 6c321b272c
commit 36445e454b
1 changed files with 38 additions and 0 deletions
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38
libhwcomposer/hwc_uevents.cpp
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@ -26,6 +26,7 @@
#include <sys/prctl.h>
#include <string.h>
#include <stdlib.h>
#include <fcntl.h>
#include "hwc_utils.h"
#include "hwc_external.h"
@ -102,11 +103,48 @@ static void *uevent_loop(void *param)
return NULL;
}
static void *vsync_loop(void *param)
{
static char buf[4096];
int fb0_vsync_fd;
fd_set exceptfds;
int res;
int64_t timestamp = 0;
hwc_context_t * ctx = reinterpret_cast<hwc_context_t *>(param);
hwc_procs* proc = (hwc_procs*)ctx->device.reserved_proc[0];
fb0_vsync_fd = open("/sys/devices/virtual/graphics/fb0/vsync_time", O_RDONLY);
if (!fb0_vsync_fd)
return NULL;
char thread_name[64] = "hwcVsyncThread";
prctl(PR_SET_NAME, (unsigned long) &thread_name, 0, 0, 0);
setpriority(PRIO_PROCESS, 0, -20);
memset(buf, 0, sizeof(buf));
ALOGI("Using sysfs mechanism for VSYNC notification");
FD_ZERO(&exceptfds);
FD_SET(fb0_vsync_fd, &exceptfds);
do {
ssize_t len = read(fb0_vsync_fd, buf, sizeof(buf));
timestamp = strtoull(buf, NULL, 0);
proc->vsync(proc, 0, timestamp);
select(fb0_vsync_fd + 1, NULL, NULL, &exceptfds, NULL);
lseek(fb0_vsync_fd, 0, SEEK_SET);
} while (1);
return NULL;
}
void init_uevent_thread(hwc_context_t* ctx)
{
pthread_t uevent_thread;
pthread_t vsync_thread;
ALOGI("Initializing UEvent Listener Thread");
pthread_create(&uevent_thread, NULL, uevent_loop, (void*) ctx);
pthread_create(&vsync_thread, NULL, vsync_loop, (void*) ctx);
}
}; //namespace