Re: [PATCH V8 1/5] PCI: loongson: Use correct pci config access operations

[Huacai Chen <chenhuacai@gmail.com>]

Hi, Bjorn,

On Thu, Aug 26, 2021 at 1:32 AM Bjorn Helgaas <helgaas@kernel.org> wrote:
>
> Things like "Use correct ..." in subject lines are useless.  *Every*
> patch should do the "proper" or "correct" thing, so it should go
> without saying.  Repeating it doesn't make it more true.
>
> This doesn't apply to *all* loongson devices, so it would be useful to
> hint at the devices it *does* apply to.
>
> Maybe something like:
>
>   PCI: loongson: Use generic 8/16/32-bit config ops on LS2K/LS7A
>
> On Wed, Aug 25, 2021 at 02:07:20PM +0800, Huacai Chen wrote:
> > LS2K/LS7A support 8/16/32-bits pci config access operations via CFG1, so
> > we can disable CFG0 for them and safely use pci_generic_config_read()/
> > pci_generic_config_write() instead of pci_generic_config_read32()/pci_
> > generic_config_write32().
>
> s/pci/PCI/
>
> > Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
> > ---
> >  drivers/pci/controller/pci-loongson.c | 36 +++++++++++++++++----------
> >  1 file changed, 23 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/pci/controller/pci-loongson.c b/drivers/pci/controller/pci-loongson.c
> > index 48169b1e3817..b2c81c762599 100644
> > --- a/drivers/pci/controller/pci-loongson.c
> > +++ b/drivers/pci/controller/pci-loongson.c
> > @@ -159,8 +159,15 @@ static int loongson_map_irq(const struct pci_dev *dev, u8 slot, u8 pin)
> >       return val;
> >  }
> >
> > -/* H/w only accept 32-bit PCI operations */
> > +/* LS2K/LS7A accept 8/16/32-bit PCI operations */
>
> *config* operations
>
> >  static struct pci_ops loongson_pci_ops = {
> > +     .map_bus = pci_loongson_map_bus,
> > +     .read   = pci_generic_config_read,
> > +     .write  = pci_generic_config_write,
> > +};
> > +
> > +/* RS780/SR5690 only accept 32-bit PCI operations */
> > +static struct pci_ops loongson_pci_ops32 = {
> >       .map_bus = pci_loongson_map_bus,
> >       .read   = pci_generic_config_read32,
> >       .write  = pci_generic_config_write32,
> > @@ -168,9 +175,9 @@ static struct pci_ops loongson_pci_ops = {
> >
> >  static const struct of_device_id loongson_pci_of_match[] = {
> >       { .compatible = "loongson,ls2k-pci",
> > -             .data = (void *)(FLAG_CFG0 | FLAG_CFG1 | FLAG_DEV_FIX), },
> > +             .data = (void *)(FLAG_CFG1 | FLAG_DEV_FIX), },
> >       { .compatible = "loongson,ls7a-pci",
> > -             .data = (void *)(FLAG_CFG0 | FLAG_CFG1 | FLAG_DEV_FIX), },
> > +             .data = (void *)(FLAG_CFG1 | FLAG_DEV_FIX), },
> >       { .compatible = "loongson,rs780e-pci",
> >               .data = (void *)(FLAG_CFG0), },
>
> It'd be nice if you used the same strategy as most other drivers,
> e.g., ".data = &loongson_ls2k_data" or similar.
>
> >       {}
> > @@ -195,17 +202,17 @@ static int loongson_pci_probe(struct platform_device *pdev)
> >       priv->pdev = pdev;
> >       priv->flags = (unsigned long)of_device_get_match_data(dev);
> >
> > -     regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > -     if (!regs) {
> > -             dev_err(dev, "missing mem resources for cfg0\n");
> > -             return -EINVAL;
> > +     if (priv->flags & FLAG_CFG0) {
> > +             regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +             if (!regs)
> > +                     dev_err(dev, "missing mem resources for cfg0\n");
> > +             else {
> > +                     priv->cfg0_base = devm_pci_remap_cfg_resource(dev, regs);
> > +                     if (IS_ERR(priv->cfg0_base))
> > +                             return PTR_ERR(priv->cfg0_base);
> > +             }
> >       }
> >
> > -     priv->cfg0_base = devm_pci_remap_cfg_resource(dev, regs);
> > -     if (IS_ERR(priv->cfg0_base))
> > -             return PTR_ERR(priv->cfg0_base);
> > -
> > -     /* CFG1 is optional */
> >       if (priv->flags & FLAG_CFG1) {
> >               regs = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> >               if (!regs)
> > @@ -218,8 +225,11 @@ static int loongson_pci_probe(struct platform_device *pdev)
> >       }
> >
> >       bridge->sysdata = priv;
> > -     bridge->ops = &loongson_pci_ops;
> >       bridge->map_irq = loongson_map_irq;
> > +     if (!of_device_is_compatible(node, "loongson,rs780e-pci"))
>
> You already called of_device_get_match_data() above, which does
> essentially the same work as of_device_is_compatible().
OK, thanks, I will update this patch.

Huacai
>
> > +             bridge->ops = &loongson_pci_ops;
> > +     else
> > +             bridge->ops = &loongson_pci_ops32;
> >
> >       return pci_host_probe(bridge);
> >  }
> > --
> > 2.27.0
> >