Fix 'assignment to __be16' warning

Message ID 20210412115302.95686-1-bence98@sch.bme.hu
State New
Headers show
Series
  • Fix 'assignment to __be16' warning
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Commit Message

Bence Csókás April 12, 2021, 11:53 a.m.
While the preamble field _is_ technically big-endian, its value is always 0x2A2A,
which is the same in either endianness, therefore it should be u16 instead.

Signed-off-by: Bence Csókás <bence98@sch.bme.hu>

---
 drivers/i2c/busses/i2c-cp2615.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Comments

Wolfram Sang April 15, 2021, 8:19 p.m. | #1
Hi Bence,

On Mon, Apr 12, 2021 at 11:53:02AM +0000, Bence Csókás wrote:
> While the preamble field _is_ technically big-endian, its value is always 0x2A2A,

> which is the same in either endianness, therefore it should be u16 instead.


Why should it be u16? I don't see it.

I thought the fix would be to add the suffix 'U' to 0x2A2A when it is
assigned to preamble?

Also, please use "i2c: cp2615: <patch header>" in the $subject

Happy hacking,

   Wolfram
Al Viro April 15, 2021, 8:37 p.m. | #2
On Mon, Apr 12, 2021 at 11:53:02AM +0000, Bence Csókás wrote:
> While the preamble field _is_ technically big-endian, its value is always 0x2A2A,

> which is the same in either endianness, therefore it should be u16 instead.


Just replace the assignment with htons(0x2A2A) and be done with that - it's
a constant expression and compiler will yield the same assembler.

Patch

diff --git a/drivers/i2c/busses/i2c-cp2615.c b/drivers/i2c/busses/i2c-cp2615.c
index 78cfecd1ea76..2824f4ba7131 100644
--- a/drivers/i2c/busses/i2c-cp2615.c
+++ b/drivers/i2c/busses/i2c-cp2615.c
@@ -38,7 +38,9 @@  enum cp2615_iop_msg_type {
 };
 
 struct __packed cp2615_iop_msg {
-	__be16 preamble, length, msg;
+	/* always 0x2A2A, which is the same in either endianness */
+	u16 preamble;
+	__be16 length, msg;
 	u8 data[MAX_IOP_PAYLOAD_SIZE];
 };