mmc: core: clarify how to use post_req in case of errors

[cascardo/linux.git] / include / linux / mmc / host.h

diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 4c4bddf..340cc0c 100644 (file)
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -109,6 +109,9 @@ struct mmc_host_ops {
         * It is optional for the host to implement pre_req and post_req in
         * order to support double buffering of requests (prepare one
         * request while another request is active).
+        * pre_req() must always be followed by a post_req().
+        * To undo a call made to pre_req(), call post_req() with
+        * a nonzero err condition.
         */
        void    (*post_req)(struct mmc_host *host, struct mmc_request *req,
                            int err);