[S390] cio: introduce cio_commit_config

To change the configuration of a subchannel we alter the modifiable
bits of the subchannel's schib field and issue a modify subchannel.
There can be the case that not all changes were applied -or worse-
quietly overwritten by the hardware. With the next store subchannel
we obtain the current state of the hardware but lose our target
configuration.

With this patch we introduce a subchannel_config structure which
contains the target subchannel configuration. Additionally the msch
wrapper cio_modify is replaced with cio_commit_config which
copies the desired changes to a temporary schib. msch is then
called with the temporary schib. This schib is only written back
to the subchannel if all changes were applied.

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

1 files changed, 6 insertions, 5 deletions

diff --git a/drivers/s390/cio/device_fsm.c b/drivers/s390/cio/device_fsm.c
index e1a3786779ba..9e249675c98d 100644
--- a/drivers/s390/cio/device_fsm.c
+++ b/drivers/s390/cio/device_fsm.c
@@ -1026,11 +1026,12 @@ void ccw_device_trigger_reprobe(struct ccw_device *cdev)
          * we have before performing device selection :/
          */
         sch->lpm = sch->schib.pmcw.pam & sch->opm;
-        /* Re-set some bits in the pmcw that were lost. */
-        sch->schib.pmcw.csense = 1;
-        sch->schib.pmcw.ena = 0;
-        if ((sch->lpm & (sch->lpm - 1)) != 0)
-                sch->schib.pmcw.mp = 1;
+        /*
+         * Use the initial configuration since we can't be shure that the old
+         * paths are valid.
+         */
+        io_subchannel_init_config(sch);
+
         /* We should also udate ssd info, but this has to wait. */
         /* Check if this is another device which appeared on the same sch. */
         if (sch->schib.pmcw.dev != cdev->private->dev_id.devno) {