It is more optimium to use wait queues while waiting for vsync so that the current task is put to sleep. This way, the task wont hog the CPU while waiting. We use wait_event_timeout and not an interruptible function since we dont want the function to exit when a signal is pending (e.g. drm release). This patch modifies the wait for vblank function of fimd.
Signed-off-by: Prathyush K prathyush.k@samsung.com --- drivers/gpu/drm/exynos/exynos_drm_fimd.c | 25 +++++++++++++++++++++---- 1 files changed, 21 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/exynos/exynos_drm_fimd.c b/drivers/gpu/drm/exynos/exynos_drm_fimd.c index 1d46286..1517d15 100644 --- a/drivers/gpu/drm/exynos/exynos_drm_fimd.c +++ b/drivers/gpu/drm/exynos/exynos_drm_fimd.c @@ -100,6 +100,8 @@ struct fimd_context { u32 vidcon1; bool suspended; struct mutex lock; + wait_queue_head_t wait_vsync_queue; + atomic_t wait_vsync_event;
struct exynos_drm_panel_info *panel; }; @@ -311,11 +313,19 @@ static void fimd_disable_vblank(struct device *dev) static void fimd_wait_for_vblank(struct device *dev) { struct fimd_context *ctx = get_fimd_context(dev); - int ret;
- ret = wait_for((__raw_readl(ctx->regs + VIDCON1) & - VIDCON1_VSTATUS_VSYNC), 50); - if (ret < 0) + if (ctx->suspended) + return; + + atomic_set(&ctx->wait_vsync_event, 1); + + /* + * wait for FIMD to signal VSYNC interrupt or return after + * timeout which is set to 50ms (refresh rate of 20). + */ + if (!wait_event_timeout(ctx->wait_vsync_queue, + !atomic_read(&ctx->wait_vsync_event), + DRM_HZ/20)) DRM_DEBUG_KMS("vblank wait timed out.\n"); }
@@ -667,6 +677,11 @@ static irqreturn_t fimd_irq_handler(int irq, void *dev_id) drm_handle_vblank(drm_dev, manager->pipe); fimd_finish_pageflip(drm_dev, manager->pipe);
+ /* set wait vsync event to zero and wake up queue. */ + if (atomic_read(&ctx->wait_vsync_event)) { + atomic_set(&ctx->wait_vsync_event, 0); + DRM_WAKEUP(&ctx->wait_vsync_queue); + } out: return IRQ_HANDLED; } @@ -885,6 +900,8 @@ static int __devinit fimd_probe(struct platform_device *pdev) ctx->vidcon1 = pdata->vidcon1; ctx->default_win = pdata->default_win; ctx->panel = panel; + DRM_INIT_WAITQUEUE(&ctx->wait_vsync_queue); + atomic_set(&ctx->wait_vsync_event, 0);
subdrv = &ctx->subdrv;