s390/pci: try harder to modify a function

In rare situations a PCI function can report a busy condition
when we issue the modify pci function command. A temporary busy
condition can exceed 1 second but not 2 seconds. Increase the
time until we report an error to 2 seconds. Also increase the
time we sleep between the retries to reduce the load in this
case.

Suggested-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/pci/pci_clp.c

@@ -179,7 +179,7 @@ error:
 static int clp_set_pci_fn(u32 *fh, u8 nr_dma_as, u8 command)
 {
 	struct clp_req_rsp_set_pci *rrb;
-	int rc, retries = 1000;
+	int rc, retries = 100;
 
 	rrb = clp_alloc_block(GFP_KERNEL);
 	if (!rrb)
@@ -199,7 +199,7 @@ static int clp_set_pci_fn(u32 *fh, u8 nr_dma_as, u8 command)
 			retries--;
 			if (retries < 0)
 				break;
-			msleep(1);
+			msleep(20);
 		}
 	} while (rrb->response.hdr.rsp == CLP_RC_SETPCIFN_BUSY);