On Mon, 18 May 2020 18:07:28 +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 subchannel is not enabled retry a predefined retries count.
>
> This tests the MSCH instruction to enable a channel succesfuly.
> This is NOT a routine to really enable the channel, no retry is done,
> in case of error, a report is made.
Hm... so you retry if the subchannel is not enabled after cc 0, but you
don't retry if the cc indicates busy/status pending? Makes sense, as we
don't expect the subchannel to be busy, but a more precise note in the
patch description would be good :)
>
> Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
> ---
> s390x/css.c | 67 +++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 67 insertions(+)
>
> diff --git a/s390x/css.c b/s390x/css.c
> index d7989d8..1b60a47 100644
> --- a/s390x/css.c
> +++ b/s390x/css.c
> @@ -16,6 +16,7 @@
> #include <string.h>
> #include <interrupt.h>
> #include <asm/arch_def.h>
> +#include <asm/time.h>
>
> #include <css.h>
>
> @@ -65,11 +66,77 @@ out:
> scn, scn_found, dev_found);
> }
>
> +#define MAX_ENABLE_RETRIES 5
> +static void test_enable(void)
> +{
> + struct pmcw *pmcw = &schib.pmcw;
> + int retry_count = 0;
> + int cc;
> +
> + if (!test_device_sid) {
> + report_skip("No device");
> + return;
> + }
> +
> + /* Read the SCHIB for this subchannel */
> + cc = stsch(test_device_sid, &schib);
> + if (cc) {
> + report(0, "stsch cc=%d", cc);
> + return;
> + }
> +
> + if (pmcw->flags & PMCW_ENABLE) {
> + report(1, "stsch: sch %08x already enabled", test_device_sid);
> + return;
> + }
> +
> +retry:
> + /* Update the SCHIB to enable the channel */
> + pmcw->flags |= PMCW_ENABLE;
> +
> + /* Tell the CSS we want to modify the subchannel */
> + cc = msch(test_device_sid, &schib);
> + if (cc) {
> + /*
> + * If the subchannel is status pending or
> + * if a function is in progress,
> + * we consider both cases as errors.
Could also be cc 3, but that would be even more weird. Just logging the
cc seems fine, though.
> + */
> + report(0, "msch cc=%d", cc);
> + return;
> + }
> +
> + /*
> + * Read the SCHIB again to verify the enablement
> + */
> + cc = stsch(test_device_sid, &schib);
> + if (cc) {
> + report(0, "stsch cc=%d", cc);
> + return;
> + }
> +
> + if (pmcw->flags & PMCW_ENABLE) {
> + report(1, "msch: sch %08x enabled after %d retries",
> + test_device_sid, retry_count);
> + return;
> + }
> +
> + if (retry_count++ < MAX_ENABLE_RETRIES) {
> + mdelay(10); /* the hardware was not ready, let it some time */
s/let/give/
> + goto retry;
> + }
> +
> + report(0,
> + "msch: enabling sch %08x failed after %d retries. pmcw: %x",
> + test_device_sid, retry_count, pmcw->flags);
> +}
> +
> static struct {
> const char *name;
> void (*func)(void);
> } tests[] = {
> { "enumerate (stsch)", test_enumerate },
> + { "enable (msch)", test_enable },
> { NULL, NULL }
> };
>
Otherwise,
Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx>
