Motorola XT897 >> Native Debian
為何Framebuffer更新很慢
drivers/video/msm/msm_fb.c
2014 static int msm_fb_pan_display(struct fb_var_screeninfo *var,
2015 struct fb_info *info)
2016 {
2017 struct mdp_display_commit disp_commit;
2018 memset(&disp_commit, 0, sizeof(disp_commit));
2019 disp_commit.var = *var;
2020 disp_commit.wait_for_finish = TRUE;
2021 return msm_fb_pan_display_ex(info, &disp_commit);
2022 }
disp_commit.wait_for_finish的設定值會決定是否須等待完成
1992 if (wait_for_finish) 1993 msm_fb_pan_idle(mfd); 1994 return ret;
比較好的作法是使用FBIO_WAITFORVSYNC，而在FBIOPAN_DISPLAY時，先將控制權交還User Application
1904 DEFINE_SEMAPHORE(msm_fb_pan_sem);
1905 static int msm_fb_pan_idle(struct msm_fb_data_type *mfd)
1906 {
1907 int ret = 0;
1908
1909 mutex_lock(&mfd->sync_mutex);
1910 if (mfd->is_committing) {
1911 mutex_unlock(&mfd->sync_mutex);
1912 ret = wait_for_completion_interruptible_timeout(
1913 &mfd->commit_comp,
1914 msecs_to_jiffies(WAIT_DISP_OP_TIMEOUT));
1915 if (ret < 0)
1916 ret = -ERESTARTSYS;
1917 else if (!ret)
1918 pr_err("%s wait for commit_comp timeout %d %d",
1919 __func__, ret, mfd->is_committing);
1920 if (ret <= 0) {
1921 mutex_lock(&mfd->sync_mutex);
1922 mfd->is_committing = 0;
1923 complete_all(&mfd->commit_comp);
1924 mutex_unlock(&mfd->sync_mutex);
1925 }
1926 } else {
1927 mutex_unlock(&mfd->sync_mutex);
1928 }
1929 return ret;
1930 }