From: Stuart Hayes commit dd65c736d1b5312c80c88a64bf521db4959eded5 upstream. The dcdbas driver can do an I/O write to cause a SMI to occur. The SMI handler looks at certain registers and memory locations, so the SMI needs to happen immediately. On some systems I/O writes are posted, though, causing the SMI to happen well after the "outb" occurred, which causes random failures. Following the "outb" with an "inb" forces the write to go through even if it is posted. Signed-off-by: Stuart Hayes Acked-by: Doug Warzecha Cc: Chuck Ebbert Signed-off-by: Jiri Kosina Signed-off-by: Greg Kroah-Hartman --- drivers/firmware/dcdbas.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/drivers/firmware/dcdbas.c +++ b/drivers/firmware/dcdbas.c @@ -267,8 +267,10 @@ int dcdbas_smi_request(struct smi_cmd *s } /* generate SMI */ + /* inb to force posted write through and make SMI happen now */ asm volatile ( - "outb %b0,%w1" + "outb %b0,%w1\n" + "inb %w1" : /* no output args */ : "a" (smi_cmd->command_code), "d" (smi_cmd->command_address), -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/