drm/amd/display: Fix race in dmub_srv_wait_for_pending

[WHY]
If commands are being submitted to DMCUB while concurrently waiting for
pending commands to complete, rptr and wptr may never match again, and
reported command count will not update.

[HOW]
Modify dmub_srv_wait_for_pending to constantly check wptr and rptr
match, and update inbox status whenever a message is sent to avoid the
race and determine message completion or idle as quickly as possible.

Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Dillon Varone <dillon.varone@amd.com>
Signed-off-by: Ray Wu <ray.wu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/display/dc/dc_dmub_srv.c b/drivers/gpu/drm/amd/display/dc/dc_dmub_srv.c
index 6115b5364394fa0d322c55db003afa93235c10af..1c6e71eaea3c3bbed8eeb5eced84553cd82b2e51 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/dc_dmub_srv.c
+++ b/drivers/gpu/drm/amd/display/dc/dc_dmub_srv.c
@@ -207,7 +207,7 @@ static bool dc_dmub_srv_fb_cmd_list_queue_execute(struct dc_dmub_srv *dc_dmub_sr
                                return false;
 
                        do {
-                               status = dmub_srv_wait_for_inbox_free(dmub, 100000, count - i);
+                                       status = dmub_srv_wait_for_inbox_free(dmub, 100000, count - i);
                        } while (dc_dmub_srv->ctx->dc->debug.disable_timeout && status != DMUB_STATUS_OK);
 
                        /* Requeue the command. */
@@ -247,6 +247,9 @@ bool dc_dmub_srv_cmd_list_queue_execute(struct dc_dmub_srv *dc_dmub_srv,
                } else {
                        res = dc_dmub_srv_fb_cmd_list_queue_execute(dc_dmub_srv, count, cmd_list);
                }
+
+               if (res)
+                       res = dmub_srv_update_inbox_status(dc_dmub_srv->dmub) == DMUB_STATUS_OK;
        }
 
        return res;

diff --git a/drivers/gpu/drm/amd/display/dmub/dmub_srv.h b/drivers/gpu/drm/amd/display/dmub/dmub_srv.h
index e759ce6ca700581107f107798d7ef4cba2295fe9..3f3fa1b6a69e8ea7c20c1ee5798ce25cdd0557a4 100644 (file)
--- a/drivers/gpu/drm/amd/display/dmub/dmub_srv.h
+++ b/drivers/gpu/drm/amd/display/dmub/dmub_srv.h
@@ -445,6 +445,8 @@ struct dmub_srv_hw_funcs {
 
        uint32_t (*emul_get_inbox1_rptr)(struct dmub_srv *dmub);
 
+       uint32_t (*emul_get_inbox1_wptr)(struct dmub_srv *dmub);
+
        void (*emul_set_inbox1_wptr)(struct dmub_srv *dmub, uint32_t wptr_offset);
 
        bool (*is_supported)(struct dmub_srv *dmub);
@@ -1053,4 +1055,16 @@ enum dmub_status dmub_srv_wait_for_inbox_free(struct dmub_srv *dmub,
                uint32_t timeout_us,
                uint32_t num_free_required);
 
+/**
+ * dmub_srv_update_inbox_status() - Updates pending status for inbox & reg inbox0
+ * @dmub: the dmub service
+ *
+ * Return:
+ *   DMUB_STATUS_OK - success
+ *   DMUB_STATUS_TIMEOUT - wait for buffer to flush timed out
+ *   DMUB_STATUS_HW_FAILURE - issue with HW programming
+ *   DMUB_STATUS_INVALID - unspecified error
+ */
+enum dmub_status dmub_srv_update_inbox_status(struct dmub_srv *dmub);
+
 #endif /* _DMUB_SRV_H_ */

diff --git a/drivers/gpu/drm/amd/display/dmub/src/dmub_srv.c b/drivers/gpu/drm/amd/display/dmub/src/dmub_srv.c
index c917a70b3c1903e38c2bac34de8cc1914679f870..acca7943a8c8289cf6f9e76e4d63b23601a891b6 100644 (file)
--- a/drivers/gpu/drm/amd/display/dmub/src/dmub_srv.c
+++ b/drivers/gpu/drm/amd/display/dmub/src/dmub_srv.c
@@ -952,10 +952,8 @@ enum dmub_status dmub_srv_wait_for_pending(struct dmub_srv *dmub,
                        !dmub->hw_funcs.get_inbox1_wptr)
                return DMUB_STATUS_INVALID;
 
-       /* take a snapshot of the required mailbox state */
-       scratch_inbox1.rb.wrpt = dmub->hw_funcs.get_inbox1_wptr(dmub);
-
        for (i = 0; i <= timeout_us; i += polling_interval_us) {
+                       scratch_inbox1.rb.wrpt = dmub->hw_funcs.get_inbox1_wptr(dmub);
                        scratch_inbox1.rb.rptr = dmub->hw_funcs.get_inbox1_rptr(dmub);
 
                scratch_reg_inbox0.is_pending = scratch_reg_inbox0.is_pending &&
@@ -978,30 +976,6 @@ enum dmub_status dmub_srv_wait_for_pending(struct dmub_srv *dmub,
        return DMUB_STATUS_TIMEOUT;
 }
 
-static enum dmub_status dmub_srv_update_inbox_status(struct dmub_srv *dmub)
-{
-       uint32_t rptr;
-
-       /* update inbox1 state */
-               rptr = dmub->hw_funcs.get_inbox1_rptr(dmub);
-
-       if (rptr > dmub->inbox1.rb.capacity)
-               return DMUB_STATUS_HW_FAILURE;
-
-       if (dmub->inbox1.rb.rptr > rptr) {
-               /* rb wrapped */
-               dmub->inbox1.num_reported += (rptr + dmub->inbox1.rb.capacity - dmub->inbox1.rb.rptr) / DMUB_RB_CMD_SIZE;
-       } else {
-               dmub->inbox1.num_reported += (rptr - dmub->inbox1.rb.rptr) / DMUB_RB_CMD_SIZE;
-       }
-       dmub->inbox1.rb.rptr = rptr;
-
-       /* update reg_inbox0 */
-       dmub_srv_update_reg_inbox0_status(dmub);
-
-       return DMUB_STATUS_OK;
-}
-
 enum dmub_status dmub_srv_wait_for_idle(struct dmub_srv *dmub,
                                        uint32_t timeout_us)
 {
@@ -1353,3 +1327,33 @@ enum dmub_status dmub_srv_wait_for_inbox_free(struct dmub_srv *dmub,
 
        return DMUB_STATUS_TIMEOUT;
 }
+
+enum dmub_status dmub_srv_update_inbox_status(struct dmub_srv *dmub)
+{
+       uint32_t rptr;
+
+       if (!dmub->hw_init)
+               return DMUB_STATUS_INVALID;
+
+       if (dmub->power_state != DMUB_POWER_STATE_D0)
+               return DMUB_STATUS_POWER_STATE_D3;
+
+       /* update inbox1 state */
+       rptr = dmub->hw_funcs.get_inbox1_rptr(dmub);
+
+       if (rptr > dmub->inbox1.rb.capacity)
+               return DMUB_STATUS_HW_FAILURE;
+
+       if (dmub->inbox1.rb.rptr > rptr) {
+               /* rb wrapped */
+               dmub->inbox1.num_reported += (rptr + dmub->inbox1.rb.capacity - dmub->inbox1.rb.rptr) / DMUB_RB_CMD_SIZE;
+       } else {
+               dmub->inbox1.num_reported += (rptr - dmub->inbox1.rb.rptr) / DMUB_RB_CMD_SIZE;
+       }
+       dmub->inbox1.rb.rptr = rptr;
+
+       /* update reg_inbox0 */
+       dmub_srv_update_reg_inbox0_status(dmub);
+
+       return DMUB_STATUS_OK;
+}