nvme: Respect timeout when en/disabling the controller

So far the driver unconditionally delays 10ms when en/disabling the
controller and still return 0 if 10ms times out. In fact, spec defines
a timeout value in the CAP register that is the worst case time that
host software shall wait for the controller to become ready.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>

diff --git a/drivers/nvme/nvme.c b/drivers/nvme/nvme.c
index d92273e67f7ba61f61b12675d06cc72a393a9a97..88679773a7a7d5e7ca25534f83d9a9386c1a5161 100644 (file)
--- a/drivers/nvme/nvme.c
+++ b/drivers/nvme/nvme.c
@@ -47,11 +47,19 @@ struct nvme_queue {
 static int nvme_wait_ready(struct nvme_dev *dev, bool enabled)
 {
        u32 bit = enabled ? NVME_CSTS_RDY : 0;
+       int timeout;
+       ulong start;
 
-       while ((readl(&dev->bar->csts) & NVME_CSTS_RDY) != bit)
-               udelay(10000);
+       /* Timeout field in the CAP register is in 500 millisecond units */
+       timeout = NVME_CAP_TIMEOUT(dev->cap) * 500;
 
-       return 0;
+       start = get_timer(0);
+       while (get_timer(start) < timeout) {
+               if ((readl(&dev->bar->csts) & NVME_CSTS_RDY) == bit)
+                       return 0;
+       }
+
+       return -ETIME;
 }
 
 static int nvme_setup_prps(struct nvme_dev *dev, u64 *prp2,