On Tue, Jun 04, 2019 at 03:22:33PM +0200, Thierry Reding wrote:
[...]
> > + } else {
> > + value = afi_readl(port->pcie, ctrl);
> > + value &= ~AFI_PEX_CTRL_RST;
> > + afi_writel(port->pcie, value, ctrl);
> > + }
> >
> > usleep_range(1000, 2000);
> >
> > - value = afi_readl(port->pcie, ctrl);
> > - value |= AFI_PEX_CTRL_RST;
> > - afi_writel(port->pcie, value, ctrl);
> > + if (port->reset_gpiod) {
> > + gpiod_set_value(port->reset_gpiod, 1);
>
> After this the port should be functional, right? I think it'd be better
> to reverse the logic here and move the polarity of the GPIO into device
> tree. gpiod_set_value() takes care of inverting the level internally if
> the GPIO is marked as low-active in DT.
>
> The end result is obviously the same, but it makes the usage much
> clearer. If somebody want to write a DT for their board, they will look
> at the schematics and see a low-active reset line and may be tempted to
> describe it as such in DT, but with your current code that would be
> exactly the wrong way around.
I agree with Thierry here, you should change the logic.
Question: what's the advantage of adding GPIO reset support if that's
architected already in port registers ? I am pretty sure there is a
reason behind it (and forgive me the dumb question) and I would like to
have it written in the commit log.
Thanks,
Lorenzo
> > + } else {
> > + value = afi_readl(port->pcie, ctrl);
> > + value |= AFI_PEX_CTRL_RST;
> > + afi_writel(port->pcie, value, ctrl);
> > + }
> > }
> >
> > static void tegra_pcie_enable_rp_features(struct tegra_pcie_port *port)
> > @@ -2238,6 +2249,7 @@ static int tegra_pcie_parse_dt(struct tegra_pcie *pcie)
> > struct tegra_pcie_port *rp;
> > unsigned int index;
> > u32 value;
> > + char *label;
> >
> > err = of_pci_get_devfn(port);
> > if (err < 0) {
> > @@ -2296,6 +2308,23 @@ static int tegra_pcie_parse_dt(struct tegra_pcie *pcie)
> > if (IS_ERR(rp->base))
> > return PTR_ERR(rp->base);
> >
> > + label = kasprintf(GFP_KERNEL, "pex-reset-%u", index);
>
> devm_kasprintf()?
>
> Thierry
>
> > + if (!label) {
> > + dev_err(dev, "failed to create reset GPIO label\n");
> > + return -ENOMEM;
> > + }
> > +
> > + rp->reset_gpiod = devm_gpiod_get_from_of_node(dev, port,
> > + "reset-gpios", 0,
> > + GPIOD_OUT_LOW,
> > + label);
> > + kfree(label);
> > + if (IS_ERR(rp->reset_gpiod)) {
> > + err = PTR_ERR(rp->reset_gpiod);
> > + dev_err(dev, "failed to get reset GPIO: %d\n", err);
> > + return err;
> > + }
> > +
> > list_add_tail(&rp->list, &pcie->ports);
> > }
> >
> > --
> > 2.17.1
> >
