On Fri, Jan 29, 2021 at 06:45:21AM +0300, Dmitry Baryshkov wrote:
> On 28/01/2021 22:26, Rob Herring wrote:
> > On Thu, Jan 28, 2021 at 11:52 AM Dmitry Baryshkov
> > <dmitry.baryshkov@xxxxxxxxxx> wrote:
> > >
> > > Some Qualcomm platforms require to power up an external device before
> > > probing the PCI bus. E.g. on RB5 platform the QCA6390 WiFi/BT chip needs
> > > to be powered up before PCIe0 bus is probed. Add a quirk to the
> > > respective PCIe root bridge to attach to the power domain if one is
> > > required, so that the QCA chip is started before scanning the PCIe bus.
> >
> > This is solving a generic problem in a specific driver. It needs to be
> > solved for any PCI host and any device.
>
> Ack. I see your point here.
>
> As this would require porting code from powerpc/spark of-pci code and
> changing pcie port driver to apply power supply before bus probing happens,
> I'd also ask for the comments from PCI maintainers. Will that solution be
> acceptable to you?
I can't say without seeing the code. I don't know enough about this
scenario to envision how it might look.
I guess the QCA6390 is a PCIe device? Why does it need to be powered
up before probing? Shouldn't we get a link-up interrupt when it is
powered up so we could probe it then?
Nit: when changing any file, please take a look at the commit history
and make yours match, e.g.,
pcie-qcom: provide a way to power up qca6390 chip on RB5 platform
does not look like:
PCI: qcom: Add support for configuring BDF to SID mapping for SM8250
PCI: qcom: Add SM8250 SoC support
PCI: qcom: Make sure PCIe is reset before init for rev 2.1.0
PCI: qcom: Replace define with standard value
PCI: qcom: Support pci speed set for ipq806x
PCI: qcom: Add ipq8064 rev2 variant
Also, if you capitalize it as "QCA6390" in the commit log, do it the
same in the subject.
> > > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> > > ---
> > > drivers/pci/controller/dwc/pcie-qcom.c | 21 +++++++++++++++++++++
> > > 1 file changed, 21 insertions(+)
> > >
> > > diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
> > > index ab21aa01c95d..eb73c8540d4d 100644
> > > --- a/drivers/pci/controller/dwc/pcie-qcom.c
> > > +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> > > @@ -20,6 +20,7 @@
> > > #include <linux/of_device.h>
> > > #include <linux/of_gpio.h>
> > > #include <linux/pci.h>
> > > +#include <linux/pm_domain.h>
> > > #include <linux/pm_runtime.h>
> > > #include <linux/platform_device.h>
> > > #include <linux/phy/phy.h>
> > > @@ -1568,6 +1569,26 @@ DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_QCOM, 0x0302, qcom_fixup_class);
> > > DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_QCOM, 0x1000, qcom_fixup_class);
> > > DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_QCOM, 0x1001, qcom_fixup_class);
> > >
> > > +static void qcom_fixup_power(struct pci_dev *dev)
> > > +{
> > > + int ret;
> > > + struct pcie_port *pp = dev->bus->sysdata;
> > > + struct dw_pcie *pci;
> > > +
> > > + if (!pci_is_root_bus(dev->bus))
> > > + return;
> > > +
> > > + ret = dev_pm_domain_attach(&dev->dev, true);
> > > + if (ret < 0 || !dev->dev.pm_domain)
> > > + return;
> > > +
> > > + pci = to_dw_pcie_from_pp(pp);
> > > + dev_info(&dev->dev, "Bus powered up, waiting for link to come up\n");
> > > +
> > > + dw_pcie_wait_for_link(pci);
> > > +}
> > > +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_QCOM, 0x010b, qcom_fixup_power);
> > > +
> > > static struct platform_driver qcom_pcie_driver = {
> > > .probe = qcom_pcie_probe,
> > > .driver = {
> > > --
> > > 2.29.2
> > >
>
>
> --
> With best wishes
> Dmitry
