firmware: ti_sci: Add comment explaining the is_secure code

Add a comment to explain the code under is_secure condition of
ti_sci_do_xfer. This will help avoid confusion amongst people who may in
future touch upon this code.

Reviewed-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Dhruva Gole <d-gole@ti.com>

diff --git a/drivers/firmware/ti_sci.c b/drivers/firmware/ti_sci.c
index b77ac36af284940e4302931c0fa6a60fa302c6ef..ee092185588116ed5b1407a8c1fddd55e5255b16 100644 (file)
--- a/drivers/firmware/ti_sci.c
+++ b/drivers/firmware/ti_sci.c
@@ -239,6 +239,12 @@ static int ti_sci_do_xfer(struct ti_sci_info *info,
        struct ti_sci_secure_msg_hdr *secure_hdr = (struct ti_sci_secure_msg_hdr *)secure_buf;
        int ret;
 
+       /*
+        * The reason why we need the is_secure code is because of boot R5.
+        * boot R5 starts off in "secure mode" when it hands off from Boot
+        * ROM over to the Secondary bootloader. The initial set of calls
+        * we have to make need to be on a secure pipe.
+        */
        if (info->is_secure) {
                /* ToDo: get checksum of the entire message */
                secure_hdr->checksum = 0;