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SubjectRe: [PATCH 22/24] thunderbolt: Add support for host and device NVM firmware upgrade
On Thu, May 18, 2017 at 10:35:19PM +0300, Andy Shevchenko wrote:
> On Thu, May 18, 2017 at 5:39 PM, Mika Westerberg
> <mika.westerberg@linux.intel.com> wrote:
> > Starting from Intel Falcon Ridge the NVM firmware can be upgraded by
> > using DMA configuration based mailbox commands. If we detect that the
> > host or device (device support starts from Intel Alpine Ridge) has the
> > DMA configuration based mailbox we expose NVM information to the
> > userspace as two separate Linux NVMem devices: nvm_active and
> > nvm_non_active. The former is read-only portion of the active NVM which
> > firmware upgrade tools can be use to find out suitable NVM image if the
> > device identification strings are not enough.
> >
> > The latter is write-only portion where the new NVM image is to be
> > written by the userspace. It is up to the userspace to find out right
> > NVM image (the kernel does very minimal validation). The ICM firmware
> > itself authenticates the new NVM firmware and fails the operation if it
> > is not what is expected.
> >
> > We also expose two new sysfs files per each switch: nvm_version and
> > nvm_authenticate which can be used to read the active NVM version and
> > start the upgrade process.
> >
> > We also introduce safe mode which is the mode a switch goes when it does
> > not have properly authenticated firmware. In this mode the switch only
> > accepts a couple of commands including flashing a new NVM firmware image
> > and triggering power cycle.
> >
> > This code is based on the work done by Amir Levy and Michael Jamet.
>
> Couple of nitpicks below.
>
> > +static ssize_t nvm_authenticate_store(struct device *dev,
> > + struct device_attribute *attr, const char *buf, size_t count)
> > +{
> > + struct tb_switch *sw = tb_to_switch(dev);
> > + unsigned int val;
> > + int ret;
> > +
> > + if (mutex_lock_interruptible(&switch_lock))
> > + return -ERESTARTSYS;
> > +
> > + ret = kstrtouint(buf, 0, &val);
> > + if (ret)
> > + goto unlock;
>
> Looking below it would be
> ret = kstrtobool(..., &x);
> if (ret)
> goto ...;
>
> if (x) {
> } else {
> }
>
> exit_unlock:
> ...

OK.

> > +
> > + switch (val) {
> > + case 0:
> > + /* Just clear the authentication status */
> > + nvm_clear_auth_status(sw);
> > + break;
> > +
> > + case 1:
> > + ret = nvm_validate_and_write(sw);
> > + if (ret)
> > + goto unlock;
> > +
> > + sw->nvm->authenticating = true;
> > +
> > + if (!tb_route(sw))
> > + ret = nvm_authenticate_host(sw);
> > + else
> > + ret = nvm_authenticate_device(sw);
> > + break;
> > +
> > + default:
> > + ret = -EINVAL;
> > + break;
> > + }
> > +
> > +unlock:
> > + mutex_unlock(&switch_lock);
> > +
> > + if (ret)
> > + return ret;
> > + return count;
> > +}
>
> > + nvm->major = val >> 16 & 0xff;
> > + nvm->minor = val >> 8 & 0xff;
>
> If lvalue is u8 or alike the conjunction becomes redundant.

It is indeed u8 so I can drop the & 0xff. Thanks.

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