Re: [PATCH v2 2/2] PCI: qcom: Add basic interconnect support

Johan Hovold
2022-11-02T08:45:20Z

On Wed, Nov 02, 2022 at 09:38:31AM +0100, Johan Hovold wrote:
> On Tue, Nov 01, 2022 at 08:05:29PM +0530, Manivannan Sadhasivam wrote:
> > On Fri, Oct 21, 2022 at 08:46:16AM +0200, Johan Hovold wrote:
> > > On Qualcomm platforms like SC8280XP and SA8540P, interconnect bandwidth
> > > must be requested before enabling interconnect clocks.
> > >
> > > Add basic support for managing an optional "pcie-mem" interconnect path
> > > by setting a low constraint before enabling clocks and updating it after
> > > the link is up.
> > >
> > > Note that it is not possible for a controller driver to set anything but
> > > a maximum peak bandwidth as expected average bandwidth will vary with
> > > use case and actual use (and power policy?). This very much remains an
> > > unresolved problem with the interconnect framework.
> > >
> > > Also note that no constraint is set for the SC8280XP/SA8540P "cpu-pcie"
> > > path for now as it is not clear what an appropriate constraint would be
> > > (and the system does not crash when left unspecified).

> > > + }
> > > +
> > > + /*
> > > + * Some Qualcomm platforms require interconnect bandwidth constraints
> > > + * to be set before enabling interconnect clocks.
> > > + *
> > > + * Set an initial peak bandwidth corresponding to single-lane Gen 1
> > > + * for the pcie-mem path.
> > > + */
> > > + ret = icc_set_bw(pcie->icc_mem, 0, MBps_to_icc(250));
> > > + if (ret) {
> > > + dev_err(pci->dev, "failed to set interconnect bandwidth: %d\n",
> > > + ret);
> >
> > Move "ret);" to prior line. No need to keep up within 80 columns.
>
> 80 chars is still a soft limit and in this case there's no real gain in
> terms of readability from breaking it.
>
> But sure, I can remove the line break.

After looking at the result, I changed my mind here and will stick to
the 80 char limit.

Johan