[PATCH v2 1/3] drm/tilcdc: Write to LCDC_END_OF_INT_IND_REG at the end of IRQ function

[Jyri Sarha]

Reorder the IRQ function so that the write to LCDC_END_OF_INT_IND_REG
is done last. The write to LCDC_END_OF_INT_IND_REG indicates to LCDC
that the interrupt service routine has completed (see section
13.3.6.1.6 in AM335x TRM). This is needed if LCDC's ipgvmodirq module
is configured for pulse interrupts.

Signed-off-by: Jyri Sarha <jsarha at ti.com>
---
 drivers/gpu/drm/tilcdc/tilcdc_crtc.c | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c 
b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
index 051e5e1..a06e73a 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
@@ -718,14 +718,19 @@ irqreturn_t tilcdc_crtc_irq(struct drm_crtc *crtc)
                        tilcdc_crtc->frame_intact = true;
        }

-       if (priv->rev == 2) {
-               if (stat & LCDC_FRAME_DONE) {
-                       tilcdc_crtc->frame_done = true;
-                       wake_up(&tilcdc_crtc->frame_done_wq);
-               }
-               tilcdc_write(dev, LCDC_END_OF_INT_IND_REG, 0);
+       if (priv->rev == 1)
+               return IRQ_HANDLED;
+       /* The rest is for revision 2 only */
+
+       if (stat & LCDC_FRAME_DONE) {
+               tilcdc_crtc->frame_done = true;
+               wake_up(&tilcdc_crtc->frame_done_wq);
        }

+       if (stat & LCDC_FIFO_UNDERFLOW)
+               dev_err_ratelimited(dev->dev, "%s(0x%08x): FIFO underfow",
+                                   __func__, stat);
+
        if (stat & LCDC_SYNC_LOST) {
                dev_err_ratelimited(dev->dev, "%s(0x%08x): Sync lost",
                                    __func__, stat);
@@ -739,9 +744,10 @@ irqreturn_t tilcdc_crtc_irq(struct drm_crtc *crtc)
                }
        }

-       if (stat & LCDC_FIFO_UNDERFLOW)
-               dev_err_ratelimited(dev->dev, "%s(0x%08x): FIFO underfow",
-                                   __func__, stat);
+       /* Indicate to LCDC that the interrupt service routine has
+        * completed, see 13.3.6.1.6 in AM335x TRM.
+        */
+       tilcdc_write(dev, LCDC_END_OF_INT_IND_REG, 0);

        return IRQ_HANDLED;
 }
-- 
1.9.1