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Message-ID: <CAKUFe6Zoo9r9tw-33VXjECX-iP=PNYJgxBb5LaOQrZ9-Tr+J6A@mail.gmail.com>
Date: Tue, 24 Sep 2019 08:58:40 +0530
From: Abhishek Shah <abhishek.shah@...adcom.com>
To: Andrew Murray <andrew.murray@....com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Ray Jui <rjui@...adcom.com>,
Scott Branden <sbranden@...adcom.com>,
linux-pci@...r.kernel.org,
linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
open list <linux-kernel@...r.kernel.org>,
BCM Kernel Feedback <bcm-kernel-feedback-list@...adcom.com>
Subject: Re: [PATCH 1/1] PCI: iproc: Invalidate PAXB address mapping before
programming it
Hi Bjorn/Lorenzo,
Can you please help review this patch?
Regards,
Abhishek
On Fri, Sep 6, 2019 at 7:41 PM Abhishek Shah <abhishek.shah@...adcom.com> wrote:
>
> Hi Andrew,
>
>
> On Fri, Sep 6, 2019 at 3:31 PM Andrew Murray <andrew.murray@....com> wrote:
> >
> > On Fri, Sep 06, 2019 at 02:55:19PM +0530, Abhishek Shah wrote:
> > > Hi Andrew,
> > >
> > > Thanks for the review. Please see my response inline:
> > >
> > > On Fri, Sep 6, 2019 at 2:08 PM Andrew Murray <andrew.murray@....com> wrote:
> > > >
> > > > On Fri, Sep 06, 2019 at 09:28:13AM +0530, Abhishek Shah wrote:
> > > > > Invalidate PAXB inbound/outbound address mapping each time before
> > > > > programming it. This is helpful for the cases where we need to
> > > > > reprogram inbound/outbound address mapping without resetting PAXB.
> > > > > kexec kernel is one such example.
> > > >
> > > > Why is this approach better than resetting the PAXB (I assume that's
> > > > the PCI controller IP)? Wouldn't resetting the PAXB address this issue,
> > > > and ensure that no other configuration is left behind?
> > > >
> > > We normally reset PAXB in the firmware(ATF). But for cases like kexec
> > > kernel boot,
> > > we do not execute any firmware code and directly boot into kernel.
> > >
> > > We could have done PAXB reset in the driver itself as you have suggested here.
> > > But note that this detail could vary for each SoC, because these
> > > registers are not part
> > > of PAXB register space itself, rather exists in a register space responsible for
> > > controlling power to various wrappers in PCIe IP. Normally, this kind
> > > of SoC specific
> > > details are handled in firmware itself, we don't bring them to driver level.
> >
> > OK understood.
> >
> > >
> > > > Or is this related to earlier boot stages loading firmware for the emulated
> > > > downstream endpoints (ep_is_internal)?
> > > >
> > > > Finally, in the case where ep_is_internal do you need to disable anything
> > > > prior to invalidating the mappings?
> > > >
> > > No, ep_is_internal is indicator for PAXC IP. It does not have
> > > mappings as in PAXB.
> >
> > I think I meant !ep_is_internal. I.e. is there possibility of inbound traffic
> > prior to invalidating the mappings. I'd assume not, but that's an assumption.
> >
> No, EP devices are not even enumerated yet.
>
> > Either way:
> >
> > Reviewed-by: Andrew Murray <andrew.murray@....com>
> >
> > >
> > >
> > > Regards,
> > > Abhishek
> > > > >
> > > > > Signed-off-by: Abhishek Shah <abhishek.shah@...adcom.com>
> > > > > Reviewed-by: Ray Jui <ray.jui@...adcom.com>
> > > > > Reviewed-by: Vikram Mysore Prakash <vikram.prakash@...adcom.com>
> > > > > ---
> > > > > drivers/pci/controller/pcie-iproc.c | 28 ++++++++++++++++++++++++++++
> > > > > 1 file changed, 28 insertions(+)
> > > > >
> > > > > diff --git a/drivers/pci/controller/pcie-iproc.c b/drivers/pci/controller/pcie-iproc.c
> > > > > index e3ca46497470..99a9521ba7ab 100644
> > > > > --- a/drivers/pci/controller/pcie-iproc.c
> > > > > +++ b/drivers/pci/controller/pcie-iproc.c
> > > > > @@ -1245,6 +1245,32 @@ static int iproc_pcie_map_dma_ranges(struct iproc_pcie *pcie)
> > > > > return ret;
> > > > > }
> > > > >
> > > > > +static void iproc_pcie_invalidate_mapping(struct iproc_pcie *pcie)
> > > > > +{
> > > > > + struct iproc_pcie_ib *ib = &pcie->ib;
> > > > > + struct iproc_pcie_ob *ob = &pcie->ob;
> > > > > + int idx;
> > > > > +
> > > > > + if (pcie->ep_is_internal)
> > > > > + return;
> > > > > +
> > > > > + if (pcie->need_ob_cfg) {
> > > > > + /* iterate through all OARR mapping regions */
> > > > > + for (idx = ob->nr_windows - 1; idx >= 0; idx--) {
> > > > > + iproc_pcie_write_reg(pcie,
> > > > > + MAP_REG(IPROC_PCIE_OARR0, idx), 0);
> > > > > + }
> > > > > + }
> > > > > +
> > > > > + if (pcie->need_ib_cfg) {
> > > > > + /* iterate through all IARR mapping regions */
> > > > > + for (idx = 0; idx < ib->nr_regions; idx++) {
> > > > > + iproc_pcie_write_reg(pcie,
> > > > > + MAP_REG(IPROC_PCIE_IARR0, idx), 0);
> > > > > + }
> > > > > + }
> > > > > +}
> > > > > +
> > > > > static int iproce_pcie_get_msi(struct iproc_pcie *pcie,
> > > > > struct device_node *msi_node,
> > > > > u64 *msi_addr)
> > > > > @@ -1517,6 +1543,8 @@ int iproc_pcie_setup(struct iproc_pcie *pcie, struct list_head *res)
> > > > > iproc_pcie_perst_ctrl(pcie, true);
> > > > > iproc_pcie_perst_ctrl(pcie, false);
> > > > >
> > > > > + iproc_pcie_invalidate_mapping(pcie);
> > > > > +
> > > > > if (pcie->need_ob_cfg) {
> > > > > ret = iproc_pcie_map_ranges(pcie, res);
> > > > > if (ret) {
> > > >
> > > > The code changes look good to me.
> > > >
> > > > Thanks,
> > > >
> > > > Andrew Murray
> > > >
> > > > > --
> > > > > 2.17.1
> > > > >
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