Re: [RFC PATCH 5/5] fsi/scom: Major overhaul

From: Benjamin Herrenschmidt
Date: Mon Jun 18 2018 - 00:47:12 EST


On Mon, 2018-06-18 at 14:09 +1000, Alistair Popple wrote:
> On Sunday, 17 June 2018 11:22:11 AM AEST Benjamin Herrenschmidt wrote:
> > On Sun, 2018-06-17 at 11:17 +1000, Benjamin Herrenschmidt wrote:
> > >
> > > We have everything that cronus needs and more than pdbg needs afaik :-)
>
> Yep, has what we need and more (such as put scom under mask and indirect scom).
> Only other useful thing would be repeated getsom/putscom operations (eg. read
> the same scom address n times) as they would help with ADU access which can do
> autoincrement or scanscom (although we should just use the scan engine directly
> for that so not a big issue).
>
> > + for (retries = 0; retries < SCOM_MAX_RETRIES; retries++) {
> > + rc = raw_get_scom(scom, value, addr, &status);
> > + if (rc) {
> > + /* Try resetting the bridge if FSI fails */
> > + if (rc != -ENODEV && retries == 0) {
> > + fsi_device_write(scom->fsi_dev, SCOM_FSI2PIB_RESET_REG,
> > + &dummy, sizeof(uint32_t));
> > + rc = -EBUSY;
> > + } else
> > + return rc;
> > + } else
> > + rc = handle_fsi2pib_status(scom, status);
> > + if (rc && rc != -EBUSY)
> > + break;
> > + if (rc == 0) {
> > + rc = handle_pib_status(scom,
> > + (status & SCOM_STATUS_PIB_RESP_MASK)
> > + >> SCOM_STATUS_PIB_RESP_SHIFT);
> > + if (rc && rc != -EBUSY)
> > + break;
> > + }
> > + if (rc == 0)
> > + break;
> > + msleep(1);
> > + }
>
> The rc handling above took me a little while to grok but I didn't come up with a
> cleaner alternative and I think it's correct.

Ack-by or Reviewed-by tag pls ? :-)

Cheers,
Ben.

> - Alistair
>
> > >
> > > That said, cronus does a bunch of other stupid things that I'm still
> > > trying to figure out how to fix.
> > >
> > > We might need to create a /dev/cfam rather than going through that
> > > magic sysfs "raw" file, and I wouldn't mind using a single IDA so that
> > > all the devices below a given FSI slace (cfam itself, sbefifo, occ,
> > > ...) have the same "number".
> >
> > Also while we're at reworking how all this is exposed to our broken
> > userspace, I wouldn't mind putting all these dev entries under a
> > directory, if I can figure out how to do that (I haven't really looked
> > yet).
> >
> > /dev/fsi/{cfamN,sbefifoN,occN, ...} and possibly similar by-id and by-
> > path that other subsystems use, so we have something more deterministic
> > than the "random number" crap we do now.
> >
> > We can always keep hacks to do symlinks in our kernel tree until we
> > have converted all our userspace users.
> >
> > We currently control the only userspace users of this, so now is a good
> > time to cleanup how we expose things. This won't always be the case.
> >
> > Cheers,
> > Ben.
> >
> >
>
>