linux-kernel - [PATCH] spi: fsi: Remove multiple sequenced ops for restricted chips

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Date:   Wed, 24 Mar 2021 17:05:16 -0500
From:   Eddie James <eajames@...ux.ibm.com>
To:     linux-spi@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, broonie@...nel.org, joel@....id.au,
        Eddie James <eajames@...ux.ibm.com>
Subject: [PATCH] spi: fsi: Remove multiple sequenced ops for restricted chips

Updated restricted chips have trouble processing multiple sequenced
operations. So remove the capability to sequence multiple operations and
reduce the maximum transfer size to 8 bytes.

Signed-off-by: Eddie James <eajames@...ux.ibm.com>
---
 drivers/spi/spi-fsi.c | 27 +++++++--------------------
 1 file changed, 7 insertions(+), 20 deletions(-)

diff --git a/drivers/spi/spi-fsi.c b/drivers/spi/spi-fsi.c
index 3920cd3286d8..de359718e816 100644
--- a/drivers/spi/spi-fsi.c
+++ b/drivers/spi/spi-fsi.c
@@ -26,7 +26,7 @@
 #define SPI_FSI_BASE			0x70000
 #define SPI_FSI_INIT_TIMEOUT_MS		1000
 #define SPI_FSI_MAX_XFR_SIZE		2048
-#define SPI_FSI_MAX_XFR_SIZE_RESTRICTED	32
+#define SPI_FSI_MAX_XFR_SIZE_RESTRICTED	8
 
 #define SPI_FSI_ERROR			0x0
 #define SPI_FSI_COUNTER_CFG		0x1
@@ -265,14 +265,12 @@ static int fsi_spi_sequence_transfer(struct fsi_spi *ctx,
 				     struct fsi_spi_sequence *seq,
 				     struct spi_transfer *transfer)
 {
-	bool docfg = false;
 	int loops;
 	int idx;
 	int rc;
 	u8 val = 0;
 	u8 len = min(transfer->len, 8U);
 	u8 rem = transfer->len % len;
-	u64 cfg = 0ULL;
 
 	loops = transfer->len / len;
 
@@ -292,28 +290,17 @@ static int fsi_spi_sequence_transfer(struct fsi_spi *ctx,
 		return -EINVAL;
 	}
 
-	if (ctx->restricted) {
-		const int eidx = rem ? 5 : 6;
-
-		while (loops > 1 && idx <= eidx) {
-			idx = fsi_spi_sequence_add(seq, val);
-			loops--;
-			docfg = true;
-		}
-
-		if (loops > 1) {
-			dev_warn(ctx->dev, "No sequencer slots; aborting.\n");
-			return -EINVAL;
-		}
+	if (ctx->restricted && loops > 1) {
+		dev_warn(ctx->dev,
+			 "Transfer too large; no branches permitted.\n");
+		return -EINVAL;
 	}
 
 	if (loops > 1) {
+		u64 cfg = SPI_FSI_COUNTER_CFG_LOOPS(loops - 1);
+
 		fsi_spi_sequence_add(seq, SPI_FSI_SEQUENCE_BRANCH(idx));
-		docfg = true;
-	}
 
-	if (docfg) {
-		cfg = SPI_FSI_COUNTER_CFG_LOOPS(loops - 1);
 		if (transfer->rx_buf)
 			cfg |= SPI_FSI_COUNTER_CFG_N2_RX |
 				SPI_FSI_COUNTER_CFG_N2_TX |
-- 
2.27.0