Re: [PATCH v2 2/3] PCI/NPEM: Add Native PCIe Enclosure Management support

[Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com>]

On Tue, 28 May 2024 22:21:10 -0700
Dan Williams <dan.j.williams@intel.com> wrote:

> > +
> > +	/*
> > +	 * For the case where a NPEM command has not completed immediately,
> > +	 * it is recommended that software not continuously “spin” on
> > polling
> > +	 * the status register, but rather poll under interrupt at a
> > reduced
> > +	 * rate; for example at 10 ms intervals.  
> 
> I think the use of read_poll_timeout() obviates the need for this
> comment. I.e. read_poll_timeout() is self documenting.
> 

This is not describing how read_poll_timeout works but why I need it at all.
I don't think that there is and ever will be a controller that needs a time to
complete the NPEM request. From my experience this is immediate action. This is
explanation why I have to keep it this way even if it has almost no sense :)

Mariusz

> > +	 *
> > +	 * PCIe r6.1 sec 6.28 "Implementation Note: Software Polling of
> > NPEM
> > +	 * Command Completed"
> > +	 */
> > +	ret = read_poll_timeout(npem_read_reg, ret_val,
> > +				ret_val || (cc_status &
> > PCI_NPEM_STATUS_CC),
> > +				10 * USEC_PER_MSEC, USEC_PER_SEC, false,
> > npem,
> > +				PCI_NPEM_STATUS, &cc_status);
> > +	if (ret)
> > +		return ret_val;