On 2020-07-09 13:40, Cornelia Huck wrote:
On Thu, 9 Jul 2020 10:07:47 +0200
Pierre Morel <pmorel@xxxxxxxxxxxxx> wrote:
A second step when testing the channel subsystem is to prepare a channel
for use.
This includes:
- Get the current subchannel Information Block (SCHIB) using STSCH
- Update it in memory to set the ENABLE bit and the specified ISC
- Tell the CSS that the SCHIB has been modified using MSCH
- Get the SCHIB from the CSS again to verify that the subchannel is
enabled and uses the specified ISC.
- If the command succeeds but subchannel is not enabled or the ISC
field is not as expected, retry a predefined retries count.
- If the command fails, report the failure and do not retry, even
if cc indicates a busy/status pending as we do not expect this.
This tests the MSCH instruction to enable a channel successfully.
Retries are done and in case of error, and if the retries count
is exceeded, a report is made.
Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
Acked-by: Thomas Huth <thuth@xxxxxxxxxx>
Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx>
---
lib/s390x/css.h | 8 +++--
lib/s390x/css_lib.c | 72 +++++++++++++++++++++++++++++++++++++++++++++
s390x/css.c | 15 ++++++++++
3 files changed, 92 insertions(+), 3 deletions(-)
(...)
+/*
+ * css_msch: enable subchannel and set with specified ISC
"css_enable: enable the subchannel with the specified ISC"
?
+ * @schid: Subchannel Identifier
+ * @isc : number of the interruption subclass to use
+ * Return value:
+ * On success: 0
+ * On error the CC of the faulty instruction
+ * or -1 if the retry count is exceeded.
+ */
+int css_enable(int schid, int isc)
+{
+ struct pmcw *pmcw = &schib.pmcw;
+ int retry_count = 0;
+ uint16_t flags;
+ int cc;
+
+ /* Read the SCHIB for this subchannel */
+ cc = stsch(schid, &schib);
+ if (cc) {
+ report_info("stsch: sch %08x failed with cc=%d", schid, cc);
+ return cc;
+ }
+
+ flags = PMCW_ENABLE | (isc << PMCW_ISC_SHIFT);
+ if ((pmcw->flags & flags) == flags) {
I think you want (pmcw->flags & PMCW_ENABLE) == PMCW_ENABLE -- this
catches the case of "subchannel has been enabled before, but with a
different isc".
If with a different ISC, we need to modify the ISC.
Don't we ?
+ report_info("stsch: sch %08x already enabled", schid);
+ return 0;
+ }
(...)
--
Pierre Morel
IBM Lab Boeblingen
