On Mon, 15 Jun 2020 11:32:00 +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
> - 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.
> - If the command succeeds but subchannel is not enabled 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 succesfuly.
> This some 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>
> ---
> lib/s390x/css_lib.c | 60 +++++++++++++++++++++++++++++++++++++++++++++
> s390x/css.c | 15 ++++++++++++
> 2 files changed, 75 insertions(+)
>
> diff --git a/lib/s390x/css_lib.c b/lib/s390x/css_lib.c
> index b0a0294..06a76db 100644
> --- a/lib/s390x/css_lib.c
> +++ b/lib/s390x/css_lib.c
> @@ -15,6 +15,7 @@
> #include <string.h>
> #include <interrupt.h>
> #include <asm/arch_def.h>
> +#include <asm/time.h>
>
> #include <css.h>
>
> @@ -68,3 +69,62 @@ out:
> scn, scn_found, dev_found);
> return schid;
> }
> +
> +int css_enable(int schid)
> +{
> + struct pmcw *pmcw = &schib.pmcw;
> + int retry_count = 0;
> + int cc;
> +
> + /* Read the SCHIB for this subchannel */
> + cc = stsch(schid, &schib);
> + if (cc) {
> + report_info("stsch failed with cc=%d", cc);
Mention the schid in the message?
> + return cc;
> + }
> +
> + if (pmcw->flags & PMCW_ENABLE) {
> + report_info("stsch: sch %08x already enabled", schid);
> + return 0;
> + }
> +
> +retry:
> + /* Update the SCHIB to enable the channel */
> + pmcw->flags |= PMCW_ENABLE;
> +
> + /* Tell the CSS we want to modify the subchannel */
> + cc = msch(schid, &schib);
> + if (cc) {
> + /*
> + * If the subchannel is status pending or
> + * if a function is in progress,
> + * we consider both cases as errors.
> + */
> + report_info("msch failed with cc=%d", cc);
> + return cc;
> + }
> +
> + /*
> + * Read the SCHIB again to verify the enablement
> + */
> + cc = stsch(schid, &schib);
> + if (cc) {
> + report_info("stsch failed with cc=%d", cc);
Also add the schid here? Maybe also add a marker to distinguish the two
cases?
> + return cc;
> + }
> +
> + if (pmcw->flags & PMCW_ENABLE) {
> + report_info("Subchannel %08x enabled after %d retries",
> + schid, retry_count);
> + return 0;
> + }
> +
> + if (retry_count++ < MAX_ENABLE_RETRIES) {
> + mdelay(10); /* the hardware was not ready, give it some time */
> + goto retry;
> + }
> +
> + report_info("msch: enabling sch %08x failed after %d retries. pmcw flags: %x",
> + schid, retry_count, pmcw->flags);
> + return -1;
> +}
With the messages updated,
Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx>
