net/mlx5: Remove spinlock support from mlx5_write64

As there is no user of mlx5_write64 that passes a spinlock to
mlx5_write64, remove this functionality and simplify the function.

Signed-off-by: Maxim Mikityanskiy <maximmi@mellanox.com>
Reviewed-by: Eran Ben Elisha <eranbe@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

2 files changed, 10 insertions, 23 deletions

diff --git a/include/linux/mlx5/cq.h b/include/linux/mlx5/cq.h
index 612c8c2f2466..769326ea1d9b 100644
--- a/include/linux/mlx5/cq.h
+++ b/include/linux/mlx5/cq.h
@@ -170,7 +170,7 @@ static inline void mlx5_cq_arm(struct mlx5_core_cq *cq, u32 cmd,
         doorbell[0] = cpu_to_be32(sn << 28 | cmd | ci);
         doorbell[1] = cpu_to_be32(cq->cqn);
 
-        mlx5_write64(doorbell, uar_page + MLX5_CQ_DOORBELL, NULL);
+        mlx5_write64(doorbell, uar_page + MLX5_CQ_DOORBELL);
 }
 
 static inline void mlx5_cq_hold(struct mlx5_core_cq *cq)
diff --git a/include/linux/mlx5/doorbell.h b/include/linux/mlx5/doorbell.h
index 9ef3f9d00154..5c267707e1df 100644
--- a/include/linux/mlx5/doorbell.h
+++ b/include/linux/mlx5/doorbell.h
@@ -36,38 +36,25 @@
 #define MLX5_BF_OFFSET        0x800
 #define MLX5_CQ_DOORBELL      0x20
 
-#if BITS_PER_LONG == 64
 /* Assume that we can just write a 64-bit doorbell atomically.  s390
  * actually doesn't have writeq() but S/390 systems don't even have
  * PCI so we won't worry about it.
+ *
+ * Note that the write is not atomic on 32-bit systems! In contrast to 64-bit
+ * ones, it requires proper locking. mlx5_write64 doesn't do any locking, so use
+ * it at your own discretion, protected by some kind of lock on 32 bits.
+ *
+ * TODO: use write{q,l}_relaxed()
  */
 
-static inline void mlx5_write64(__be32 val[2], void __iomem *dest,
-                                spinlock_t *doorbell_lock)
+static inline void mlx5_write64(__be32 val[2], void __iomem *dest)
 {
+#if BITS_PER_LONG == 64
         __raw_writeq(*(u64 *)val, dest);
-}
-
 #else
-
-/* Just fall back to a spinlock to protect the doorbell if
- * BITS_PER_LONG is 32 -- there's no portable way to do atomic 64-bit
- * MMIO writes.
- */
-
-static inline void mlx5_write64(__be32 val[2], void __iomem *dest,
-                                spinlock_t *doorbell_lock)
-{
-        unsigned long flags;
-
-        if (doorbell_lock)
-                spin_lock_irqsave(doorbell_lock, flags);
         __raw_writel((__force u32) val[0], dest);
         __raw_writel((__force u32) val[1], dest + 4);
-        if (doorbell_lock)
-                spin_unlock_irqrestore(doorbell_lock, flags);
-}
-
 #endif
+}
 
 #endif /* MLX5_DOORBELL_H */