irqchip/gic-v3-its: Add post-mortem info on command timeout

If the ITS stops processing commands, we're pretty much toasted
as we cannot update the configuration anymore (and we're not
even sure that the ITS still translates interrups).

If that happens, let's dump some basic information about the
state of affairs before moving on.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 54ea4e26c7a941cecae0a70ae60815ad39dd680e..0788de9a5407387c3be1dce64596ef1ab5820c90 100644 (file)
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -690,9 +690,9 @@ static void its_flush_cmd(struct its_node *its, struct its_cmd_block *cmd)
                dsb(ishst);
 }
 
-static void its_wait_for_range_completion(struct its_node *its,
-                                         struct its_cmd_block *from,
-                                         struct its_cmd_block *to)
+static int its_wait_for_range_completion(struct its_node *its,
+                                        struct its_cmd_block *from,
+                                        struct its_cmd_block *to)
 {
        u64 rd_idx, from_idx, to_idx;
        u32 count = 1000000;    /* 1s! */
@@ -713,12 +713,15 @@ static void its_wait_for_range_completion(struct its_node *its,
 
                count--;
                if (!count) {
-                       pr_err_ratelimited("ITS queue timeout\n");
-                       return;
+                       pr_err_ratelimited("ITS queue timeout (%llu %llu %llu)\n",
+                                          from_idx, to_idx, rd_idx);
+                       return -1;
                }
                cpu_relax();
                udelay(1);
        }
+
+       return 0;
 }
 
 /* Warning, macro hell follows */
@@ -754,7 +757,8 @@ post:                                                                       \
        next_cmd = its_post_commands(its);                              \
        raw_spin_unlock_irqrestore(&its->lock, flags);                  \
                                                                        \
-       its_wait_for_range_completion(its, cmd, next_cmd);              \
+       if (its_wait_for_range_completion(its, cmd, next_cmd))          \
+               pr_err_ratelimited("ITS cmd %ps failed\n", builder);    \
 }
 
 static void its_build_sync_cmd(struct its_cmd_block *sync_cmd,