linux-kernel - [PATCH 1/2] rslib: Minimum symbol size for a Reed-Solomon code is 2 bits not 1 bit

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Date:   Sun, 1 Mar 2020 21:27:42 -0700
From:   Cody Planteen <planteen@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     tglx@...utronix.de
Subject: [PATCH 1/2] rslib: Minimum symbol size for a Reed-Solomon code is 2
 bits not 1 bit

The minimum field for a R-S code is GF(2**2). A code in GF(2**1) would
only be 1 symbol long including data and parity which does not make sense.

Signed-off-by: Cody Planteen <planteen@...il.com>
---
 include/linux/rslib.h           | 4 ++--
 lib/reed_solomon/reed_solomon.c | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/linux/rslib.h b/include/linux/rslib.h
index 5974cedd008c..3e48d4302908 100644
--- a/include/linux/rslib.h
+++ b/include/linux/rslib.h
@@ -57,7 +57,7 @@ struct rs_control {
 	uint16_t	buffers[0];
 };
 
-/* General purpose RS codec, 8-bit data width, symbol width 1-15 bit  */
+/* General purpose RS codec, 8-bit data width, symbol width 2-15 bit  */
 #ifdef CONFIG_REED_SOLOMON_ENC8
 int encode_rs8(struct rs_control *rs, uint8_t *data, int len, uint16_t *par,
 	       uint16_t invmsk);
@@ -68,7 +68,7 @@ int decode_rs8(struct rs_control *rs, uint8_t *data, uint16_t *par, int len,
 	       uint16_t *corr);
 #endif
 
-/* General purpose RS codec, 16-bit data width, symbol width 1-15 bit  */
+/* General purpose RS codec, 16-bit data width, symbol width 2-15 bit  */
 #ifdef CONFIG_REED_SOLOMON_ENC16
 int encode_rs16(struct rs_control *rs, uint16_t *data, int len, uint16_t *par,
 		uint16_t invmsk);
diff --git a/lib/reed_solomon/reed_solomon.c b/lib/reed_solomon/reed_solomon.c
index bbc01bad3053..357723ac252f 100644
--- a/lib/reed_solomon/reed_solomon.c
+++ b/lib/reed_solomon/reed_solomon.c
@@ -219,7 +219,7 @@ static struct rs_control *init_rs_internal(int symsize, int gfpoly,
 	unsigned int bsize;
 
 	/* Sanity checks */
-	if (symsize < 1)
+	if (symsize < 2)
 		return NULL;
 	if (fcr < 0 || fcr >= (1<<symsize))
 		return NULL;
-- 
2.20.1