[PATCH V4 16/17] i3c: mipi-i3c-hci: Consolidate DMA ring allocation

[Adrian Hunter]

dma_alloc_coherent() allocates memory in whole pages, which can waste
space when command and response queues are allocated separately.

Allocate the DMA command and response queues from a single coherent
allocation instead, while preserving the required 4-byte alignment.

This reduces memory overhead without changing behavior.

Signed-off-by: Adrian Hunter <adrian.hunter at intel.com>
---


Changes in V4:

	Cache allocation size in rh->xfer_alloc_sz to avoid recomputing in
	hci_dma_free()

Changes in V3:

	None

Changes in V2:

	Check for failed allocation before assignments to avoid doing
	arithmetic with NULL pointers


 drivers/i3c/master/mipi-i3c-hci/dma.c | 21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/drivers/i3c/master/mipi-i3c-hci/dma.c b/drivers/i3c/master/mipi-i3c-hci/dma.c
index 9a01c740760f..0136f3064ada 100644
--- a/drivers/i3c/master/mipi-i3c-hci/dma.c
+++ b/drivers/i3c/master/mipi-i3c-hci/dma.c
@@ -130,7 +130,7 @@ struct hci_rh_data {
 	dma_addr_t xfer_dma, resp_dma, ibi_status_dma, ibi_data_dma;
 	unsigned int xfer_entries, ibi_status_entries, ibi_chunks_total;
 	unsigned int xfer_struct_sz, resp_struct_sz, ibi_status_sz, ibi_chunk_sz;
-	unsigned int done_ptr, ibi_chunk_ptr, xfer_space;
+	unsigned int xfer_alloc_sz, done_ptr, ibi_chunk_ptr, xfer_space;
 	struct hci_xfer **src_xfers;
 	struct completion op_done;
 };
@@ -187,13 +187,7 @@ static void hci_dma_free(void *data)
 		rh = &rings->headers[i];
 
 		if (rh->xfer)
-			dma_free_coherent(rings->sysdev,
-					  rh->xfer_struct_sz * rh->xfer_entries,
-					  rh->xfer, rh->xfer_dma);
-		if (rh->resp)
-			dma_free_coherent(rings->sysdev,
-					  rh->resp_struct_sz * rh->xfer_entries,
-					  rh->resp, rh->resp_dma);
+			dma_free_coherent(rings->sysdev, rh->xfer_alloc_sz, rh->xfer, rh->xfer_dma);
 		kfree(rh->src_xfers);
 		if (rh->ibi_status)
 			dma_free_coherent(rings->sysdev,
@@ -359,18 +353,19 @@ static int hci_dma_init(struct i3c_hci *hci)
 		dev_dbg(&hci->master.dev,
 			"xfer_struct_sz = %d, resp_struct_sz = %d",
 			rh->xfer_struct_sz, rh->resp_struct_sz);
-		xfers_sz = rh->xfer_struct_sz * rh->xfer_entries;
+		xfers_sz = round_up(rh->xfer_struct_sz * rh->xfer_entries, 4);
 		resps_sz = rh->resp_struct_sz * rh->xfer_entries;
+		rh->xfer_alloc_sz = xfers_sz + resps_sz;
 
-		rh->xfer = dma_alloc_coherent(rings->sysdev, xfers_sz,
+		rh->xfer = dma_alloc_coherent(rings->sysdev, rh->xfer_alloc_sz,
 					      &rh->xfer_dma, GFP_KERNEL);
-		rh->resp = dma_alloc_coherent(rings->sysdev, resps_sz,
-					      &rh->resp_dma, GFP_KERNEL);
 		rh->src_xfers =
 			kzalloc_objs(*rh->src_xfers, rh->xfer_entries);
 		ret = -ENOMEM;
-		if (!rh->xfer || !rh->resp || !rh->src_xfers)
+		if (!rh->xfer || !rh->src_xfers)
 			goto err_out;
+		rh->resp = rh->xfer + xfers_sz;
+		rh->resp_dma = rh->xfer_dma + xfers_sz;
 
 		/* IBIs */
 
-- 
2.51.0