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drm: adp: Handle drm_crtc_vblank_get() errors
drm_crtc_vblank_get() may fail when it's called before drm_crtc_vblank_on() on a resetted CRTC. This occurs in drm_crtc_helper_funcs' atomic_flush() calls after drm_atomic_helper_crtc_reset() for example directly after probe. Send the vblank event directly in such cases. Avoids following warning in the subsequent drm_crtc_vblank_put() call from the vblank irq handler as below: adp 228200000.display-pipe: [drm] drm_WARN_ON(atomic_read(&vblank->refcount) == 0) WARNING: CPU: 5 PID: 1206 at drivers/gpu/drm/drm_vblank.c:1247 drm_vblank_put+0x158/0x170 ... Call trace: drm_vblank_put+0x158/0x170 (P) drm_crtc_vblank_put+0x24/0x38 adp_fe_irq+0xd8/0xe8 [adpdrm] __handle_irq_event_percpu+0x94/0x318 handle_irq_event+0x54/0xd0 handle_fasteoi_irq+0xa8/0x240 handle_irq_desc+0x3c/0x68 generic_handle_domain_irq+0x24/0x40 Modifying `crtc->state->event` here is fine as crtc->mutex is locked by the non-async atomic commit. In retrospect this looks so obvious that it doesn't warrant a comment in the file. Signed-off-by: Janne Grunau <[email protected]> Reviewed-by: Alyssa Rosenzweig <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Alyssa Rosenzweig <[email protected]>
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drivers/gpu/drm/adp/adp_drv.c

Lines changed: 11 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -331,13 +331,19 @@ static void adp_crtc_atomic_flush(struct drm_crtc *crtc,
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}
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writel(ADBE_FIFO_SYNC | frame_num, adp->be + ADBE_FIFO);
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//FIXME: use adbe flush interrupt
334-
spin_lock_irqsave(&crtc->dev->event_lock, flags);
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if (crtc->state->event) {
336-
drm_crtc_vblank_get(crtc);
337-
adp->event = crtc->state->event;
335+
struct drm_pending_vblank_event *event = crtc->state->event;
336+
337+
crtc->state->event = NULL;
338+
spin_lock_irqsave(&crtc->dev->event_lock, flags);
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340+
if (drm_crtc_vblank_get(crtc) != 0)
341+
drm_crtc_send_vblank_event(crtc, event);
342+
else
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adp->event = event;
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spin_unlock_irqrestore(&crtc->dev->event_lock, flags);
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}
339-
crtc->state->event = NULL;
340-
spin_unlock_irqrestore(&crtc->dev->event_lock, flags);
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}
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static const struct drm_crtc_funcs adp_crtc_funcs = {

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