[PATCH 4/7] memory: renesas-rpc-if: Consolidate XSPI_CDTBUF0 updates in read path

[Prabhakar]

From: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>

Program the XSPI_CDTBUF0 fields used by the RPCIF_DATA_IN transfer path
through a single regmap_update_bits() call.

The existing code updates TRTYPE, DATASIZE, ADDSIZE and LATE using
multiple read-modify-write operations on the same register, even though
all field values are known before the transfer starts.

Build the register mask and value first, then perform a single register
update. This reduces register accesses and simplifies the transfer setup
without changing functionality.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
---
 drivers/memory/renesas-rpc-if.c | 31 +++++++++++++++++--------------
 1 file changed, 17 insertions(+), 14 deletions(-)

diff --git a/drivers/memory/renesas-rpc-if.c b/drivers/memory/renesas-rpc-if.c
index e406afc42616..c768e9c18556 100644
--- a/drivers/memory/renesas-rpc-if.c
+++ b/drivers/memory/renesas-rpc-if.c
@@ -697,30 +697,33 @@ static int xspi_manual_xfer_impl(struct rpcif_priv *xspi)
 		while (pos < xspi->xferlen) {
 			u32 bytes_left = xspi->xferlen - pos;
 			u32 nbytes, data[2], *p = data;
-
-			regmap_update_bits(xspi->regmap, XSPI_CDTBUF0,
-					   XSPI_CDTBUF_TRTYPE,
-					   ~(u32)XSPI_CDTBUF_TRTYPE);
+			u32 cdtbuf0_mask, cdtbuf0_val;
 
 			/* nbytes can be up to 8 bytes */
 			nbytes = bytes_left >= max ? max : bytes_left;
 
-			regmap_update_bits(xspi->regmap, XSPI_CDTBUF0,
-					   XSPI_CDTBUF_DATASIZE(0xf),
-					   XSPI_CDTBUF_DATASIZE(nbytes));
+			/* clear TRTYPE */
+			cdtbuf0_mask = XSPI_CDTBUF_TRTYPE;
+			cdtbuf0_val = 0;
 
-			regmap_update_bits(xspi->regmap, XSPI_CDTBUF0,
-					   XSPI_CDTBUF_ADDSIZE(0x7),
-					   XSPI_CDTBUF_ADDSIZE(xspi->addr_nbytes));
+			/* program DATASIZE */
+			cdtbuf0_mask |= XSPI_CDTBUF_DATASIZE(0xf);
+			cdtbuf0_val |= XSPI_CDTBUF_DATASIZE(nbytes);
+
+			/* program ADDSIZE */
+			cdtbuf0_mask |= XSPI_CDTBUF_ADDSIZE(0x7);
+			cdtbuf0_val |= XSPI_CDTBUF_ADDSIZE(xspi->addr_nbytes);
+
+			/* program LATE */
+			cdtbuf0_mask |= XSPI_CDTBUF_LATE(0x1f);
+			cdtbuf0_val |= XSPI_CDTBUF_LATE(xspi->dummy);
+
+			regmap_update_bits(xspi->regmap, XSPI_CDTBUF0, cdtbuf0_mask, cdtbuf0_val);
 
 			if (xspi->addr_nbytes)
 				regmap_write(xspi->regmap, XSPI_CDABUF0,
 					     xspi->smadr + pos);
 
-			regmap_update_bits(xspi->regmap, XSPI_CDTBUF0,
-					   XSPI_CDTBUF_LATE(0x1f),
-					   XSPI_CDTBUF_LATE(xspi->dummy));
-
 			regmap_update_bits(xspi->regmap, XSPI_CDCTL0,
 					   XSPI_CDCTL0_TRREQ, XSPI_CDCTL0_TRREQ);
 
-- 
2.54.0