arm: socfpga: mailbox: Fix off-by-one error on command length checking

A mailbox command contains 1-u32 header + arguments. The "len" variable
only contains the length of the arguments, but not the 1-u32 header.
Include the length of header when checking the ring buffer space to
prevent off-by-one error.

Signed-off-by: Ley Foon Tan <ley.foon.tan@intel.com>
Signed-off-by: Chee Hong Ang <chee.hong.ang@intel.com>

diff --git a/arch/arm/mach-socfpga/mailbox_s10.c b/arch/arm/mach-socfpga/mailbox_s10.c
index 3c33223..4498ab5 100644 (file)
--- a/arch/arm/mach-socfpga/mailbox_s10.c
+++ b/arch/arm/mach-socfpga/mailbox_s10.c
@@ -55,11 +55,11 @@ static __always_inline int mbox_fill_cmd_circular_buff(u32 header, u32 len,
        cout = MBOX_READL(MBOX_COUT) % MBOX_CMD_BUFFER_SIZE;
 
        /* if command buffer is full or not enough free space
-        * to fit the data
+        * to fit the data. Note, len is in u32 unit.
         */
        if (((cin + 1) % MBOX_CMD_BUFFER_SIZE) == cout ||
            ((MBOX_CMD_BUFFER_SIZE - cin + cout - 1) %
-            MBOX_CMD_BUFFER_SIZE) < len)
+            MBOX_CMD_BUFFER_SIZE) < (len + 1))
                return -ENOMEM;
 
        /* write header to circular buffer */