From: Jacopo Mondi <jacopo.mondi+renesas@ideasonboard.com>

The CRU cycles over the hardware slots where the destination address for
the next frame has to be programmed.

The RZ/G2L version of the IP has a register that tells which is the
last used slot by the hardware but, unfortunately, such register is not
available on RZ/G3E and RZ/V2H(P).

The driver currently compares the value of the AMnMADRSL/H register
which report "the memory address which the current video data was
written to" and compares it with the address programmed in the slots.

This heuristic requires a bit of book keeping and proper locking. As the
driver handles the FrameEnd interrupt, it's way easier to keep track
of the slot that has been used by ourselves with a driver variable.

Signed-off-by: Jacopo Mondi <jacopo.mondi+renesas@ideasonboard.com>
Tested-by: Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>
Reviewed-by: Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>
Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
---
 .../media/platform/renesas/rzg2l-cru/rzg2l-cru.h   |  6 +++--
 .../media/platform/renesas/rzg2l-cru/rzg2l-video.c | 31 +++-------------------
 2 files changed, 7 insertions(+), 30 deletions(-)

diff --git a/drivers/media/platform/renesas/rzg2l-cru/rzg2l-cru.h b/drivers/media/platform/renesas/rzg2l-cru/rzg2l-cru.h
index 12d574182eb8..25f17069585c 100644
--- a/drivers/media/platform/renesas/rzg2l-cru/rzg2l-cru.h
+++ b/drivers/media/platform/renesas/rzg2l-cru/rzg2l-cru.h
@@ -119,9 +119,10 @@ struct rzg2l_cru_info {
  * @mdev_lock:		protects the count, notifier and csi members
  * @pad:		media pad for the video device entity
  *
- * @hw_lock:		protects the slot counter, hardware programming of
- *			slot addresses and the @buf_addr[] list
+ * @hw_lock:		protects the @active_slot counter, hardware programming
+ *			of slot addresses and the @buf_addr[] list
  * @buf_addr:		Memory addresses where current video data is written
+ * @active_slot:	The slot in use
  *
  * @lock:		protects @queue
  * @queue:		vb2 buffers queue
@@ -162,6 +163,7 @@ struct rzg2l_cru_dev {
 
 	spinlock_t hw_lock;
 	dma_addr_t buf_addr[RZG2L_CRU_HW_BUFFER_DEFAULT];
+	unsigned int active_slot;
 
 	struct mutex lock;
 	struct vb2_queue queue;
diff --git a/drivers/media/platform/renesas/rzg2l-cru/rzg2l-video.c b/drivers/media/platform/renesas/rzg2l-cru/rzg2l-video.c
index 5769dbcbd084..b02940369a18 100644
--- a/drivers/media/platform/renesas/rzg2l-cru/rzg2l-video.c
+++ b/drivers/media/platform/renesas/rzg2l-cru/rzg2l-video.c
@@ -634,31 +634,6 @@ irqreturn_t rzg2l_cru_irq(int irq, void *data)
 	return IRQ_RETVAL(handled);
 }
 
-static int rzg3e_cru_get_current_slot(struct rzg2l_cru_dev *cru)
-{
-	u64 amnmadrs;
-	int slot;
-
-	/*
-	 * When AMnMADRSL is read, AMnMADRSH of the higher-order
-	 * address also latches the address.
-	 *
-	 * AMnMADRSH must be read after AMnMADRSL has been read.
-	 */
-	amnmadrs = rzg2l_cru_read(cru, AMnMADRSL);
-	amnmadrs |= (u64)rzg2l_cru_read(cru, AMnMADRSH) << 32;
-
-	/* Ensure amnmadrs is within this buffer range */
-	for (slot = 0; slot < cru->num_buf; slot++) {
-		if (amnmadrs >= cru->buf_addr[slot] &&
-		    amnmadrs < cru->buf_addr[slot] + cru->format.sizeimage)
-			return slot;
-	}
-
-	dev_err(cru->dev, "Invalid MB address 0x%llx (out of range)\n", amnmadrs);
-	return -EINVAL;
-}
-
 irqreturn_t rzg3e_cru_irq(int irq, void *data)
 {
 	struct rzg2l_cru_dev *cru = data;
@@ -690,9 +665,8 @@ irqreturn_t rzg3e_cru_irq(int irq, void *data)
 		return IRQ_HANDLED;
 	}
 
-	slot = rzg3e_cru_get_current_slot(cru);
-	if (slot < 0)
-		return IRQ_HANDLED;
+	slot = cru->active_slot;
+	cru->active_slot = (cru->active_slot + 1) % cru->num_buf;
 
 	dev_dbg(cru->dev, "Current written slot: %d\n", slot);
 	cru->buf_addr[slot] = 0;
@@ -769,6 +743,7 @@ static int rzg2l_cru_start_streaming_vq(struct vb2_queue *vq, unsigned int count
 		goto assert_presetn;
 	}
 
+	cru->active_slot = 0;
 	cru->sequence = 0;
 
 	ret = rzg2l_cru_set_stream(cru, 1);

-- 
2.53.0