Bad DT binding (hisi-pcie-almost-ecam)

Hi Mark

> -----Original Message-----
> From: Mark Rutland [mailto:mark.rutland@arm.com]
> Sent: 10 March 2017 17:41
> To: liudongdong (C); Bjorn Helgaas
> Cc: Gabriele Paoloni; Wangzhou (B); devicetree@vger.kernel.org; linux-
> pci@vger.kernel.org; linux-kernel@vger.kernel.org
> Subject: Bad DT binding (hisi-pcie-almost-ecam)
> 
> I've just spotted commit:
> 
>   a2ec1996098c7da0 ("PCI: hisi: Add DT almost-ECAM support for
> Hip06/Hip07 host controllers")
> 
> ... which went in for v4.11-rc1.
> 
> I hadn't seen this until now, and as far as I can tell this never went
> to the devicetree list.

Sorry about this, we'll be more careful next time

> 
> The commit adds the "hisilicon,pcie-almost-ecam", which goes against
> the
> usual DT conventions, and is non-sensical in that it describes the IP
> based on what it isn't.
> 
> This binding shouldn't have gone in as-is, and we should fix it before
> v4.11.
> 
> The binding states that this IP is found in Hip06 and Hip07. For these
> cases we'd usually take the name of the first implementation, e.g.
> something like "hisilicon,hip06-pcie", which can be used as a fallback
> in the compatible list if reused in subsequent SoC generations.
> 
> I also see that "hisilicon,hip06-pcie" already exists, so I'm even more
> suspicious.

For Hip06 the IP is the same but in we have a different BIOS configuration
that allows the controller be ECAM compliant for all the devices of the
hierarchy except the RC.

> 
> What exactly is the "hisilicon,pcie-almost-ecam" binding trying to
> describe? Is it a different IP also found on Hip06, or is it a new
> binding for the same IP?

The reason why we need this new BIOS is to support the recent PCIe quirks
for the ACPI Root Port driver (commit 5b69b85ba1ddd36be01f5c57830b37a3c8256009
"PCI/ACPI: Check for platform-specific MCFG quirks"). So using one BIOS we
support both DT and ACPI.
This is the reason why you see Hip-06 being already there...

About the name to use here from what you suggest we should use
"hisilicon,hip06-pcie-almost-ecam" and re-use it for hip07 SoC.
To be honest I would prefer it either as it is now or to modify the
driver as:


What do you think?

Many Thanks
Gab


> 
> Thanks,
> Mark.

On Mon, Mar 13, 2017 at 9:14 AM, Gabriele Paoloni
<gabriele.paoloni@huawei.com> wrote:
> About the name to use here from what you suggest we should use
> "hisilicon,hip06-pcie-almost-ecam" and re-use it for hip07 SoC.
> To be honest I would prefer it either as it is now or to modify the
> driver as:
>
> diff --git a/drivers/pci/dwc/pcie-hisi.c b/drivers/pci/dwc/pcie-hisi.c
> index 52f1e3f..7527b4c 100644
> --- a/drivers/pci/dwc/pcie-hisi.c
> +++ b/drivers/pci/dwc/pcie-hisi.c
> @@ -381,7 +381,11 @@ struct pci_ecam_ops hisi_pcie_platform_ops = {
>
>   static const struct of_device_id hisi_pcie_almost_ecam_of_match[] = {
>          {
> -           .compatible = "hisilicon,pcie-almost-ecam",
> +         .compatible = "hisilicon,pcie-almost-ecam-hip06",

Shouldn't that be "hisilicon,hip06-pcie-almost-ecam"?

> +         .data           = (void *) &hisi_pcie_platform_ops,
> + },
> + {
> +         .compatible = "hisilicon,pcie-almost-ecam-hip07",

Shouldn't that be "hisilicon,hip07-pcie-almost-ecam"?

>                  .data       = (void *) &hisi_pcie_platform_ops,
>          },

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Hi Geert

[...]

> >          {

> > -           .compatible = "hisilicon,pcie-almost-ecam",

> > +         .compatible = "hisilicon,pcie-almost-ecam-hip06",

> 

> Shouldn't that be "hisilicon,hip06-pcie-almost-ecam"?

> 

> > +         .data           = (void *) &hisi_pcie_platform_ops,

> > + },

> > + {

> > +         .compatible = "hisilicon,pcie-almost-ecam-hip07",

> 

> Shouldn't that be "hisilicon,hip07-pcie-almost-ecam"?


Indeed prefixing the SoC name is more consistent and it looks better

Many thanks
Gab

> 

> >                  .data       = (void *) &hisi_pcie_platform_ops,

> >          },

> 

> Gr{oetje,eeting}s,

> 

>                         Geert

> 

> --

> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-

> m68k.org

> 

> In personal conversations with technical people, I call myself a

> hacker. But

> when I'm talking to journalists I just say "programmer" or something

> like that.

>                                 -- Linus Torvalds