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SubjectRe: [PATCHv5 18/20] PCI: mobiveil: Disable IB and OB windows set by bootloader
On Sat, Jun 15, 2019 at 05:03:33AM +0000, Z.q. Hou wrote:
> Hi Lorenzo,
>
> > -----Original Message-----
> > From: Lorenzo Pieralisi [mailto:lorenzo.pieralisi@arm.com]
> > Sent: 2019年6月13日 0:24
> > To: Z.q. Hou <zhiqiang.hou@nxp.com>; bhelgaas@google.com
> > Cc: linux-pci@vger.kernel.org; linux-arm-kernel@lists.infradead.org;
> > devicetree@vger.kernel.org; linux-kernel@vger.kernel.org;
> > robh+dt@kernel.org; mark.rutland@arm.com; l.subrahmanya@mobiveil.co.in;
> > shawnguo@kernel.org; Leo Li <leoyang.li@nxp.com>;
> > catalin.marinas@arm.com; will.deacon@arm.com; Mingkai Hu
> > <mingkai.hu@nxp.com>; M.h. Lian <minghuan.lian@nxp.com>; Xiaowei Bao
> > <xiaowei.bao@nxp.com>
> > Subject: Re: [PATCHv5 18/20] PCI: mobiveil: Disable IB and OB windows set
> > by bootloader
> >
> > On Fri, Apr 12, 2019 at 08:37:00AM +0000, Z.q. Hou wrote:
> > > From: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
> > >
> > > Disable all inbound and outbound windows before set up the windows in
> > > kernel, in case transactions match the window set by bootloader.
> >
> > There must be no PCI transactions ongoing at bootloader<->OS handover.
> >
>
> Yes, exact.
>
> > The bootloader needs fixing and this patch should be dropped, the host bridge
> > driver assumes the host bridge state is disabled,
>
> The host bridge driver should not assumes the host state is disabled,
> actually u-boot enable/initialize the host and without disabling it
> when transfer the control to Linux.

Fix the bootloader and drop this patch, I explain to you why.

> > it will program the bridge
> > apertures from scratch with no ongoing transactions, anything deviating from
> > this behaviour is a bootloader bug and a recipe for disaster.
>
> The point of this patch is not to fix the ongoing transaction issue,
> it is to avoid a potential issue which is caused by the outbound
> window enabled by bootloader overlapping with Linux enabled.

See above.

Lorenzo

> Thanks,
> Zhiqiang
>
> > Lorenzo
> >
> > > Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
> > > Reviewed-by: Minghuan Lian <Minghuan.Lian@nxp.com>
> > > Reviewed-by: Subrahmanya Lingappa <l.subrahmanya@mobiveil.co.in>
> > > ---
> > > V5:
> > > - No functionality change.
> > >
> > > drivers/pci/controller/pcie-mobiveil.c | 25 +++++++++++++++++++++++++
> > > 1 file changed, 25 insertions(+)
> > >
> > > diff --git a/drivers/pci/controller/pcie-mobiveil.c
> > > b/drivers/pci/controller/pcie-mobiveil.c
> > > index 8dc87c7a600e..411e9779da12 100644
> > > --- a/drivers/pci/controller/pcie-mobiveil.c
> > > +++ b/drivers/pci/controller/pcie-mobiveil.c
> > > @@ -565,6 +565,24 @@ static int mobiveil_bringup_link(struct
> > mobiveil_pcie *pcie)
> > > return -ETIMEDOUT;
> > > }
> > >
> > > +static void mobiveil_pcie_disable_ib_win(struct mobiveil_pcie *pcie,
> > > +int idx) {
> > > + u32 val;
> > > +
> > > + val = csr_readl(pcie, PAB_PEX_AMAP_CTRL(idx));
> > > + val &= ~(1 << AMAP_CTRL_EN_SHIFT);
> > > + csr_writel(pcie, val, PAB_PEX_AMAP_CTRL(idx)); }
> > > +
> > > +static void mobiveil_pcie_disable_ob_win(struct mobiveil_pcie *pcie,
> > > +int idx) {
> > > + u32 val;
> > > +
> > > + val = csr_readl(pcie, PAB_AXI_AMAP_CTRL(idx));
> > > + val &= ~(1 << WIN_ENABLE_SHIFT);
> > > + csr_writel(pcie, val, PAB_AXI_AMAP_CTRL(idx)); }
> > > +
> > > static void mobiveil_pcie_enable_msi(struct mobiveil_pcie *pcie) {
> > > phys_addr_t msg_addr = pcie->pcie_reg_base; @@ -585,6 +603,13 @@
> > > static int mobiveil_host_init(struct mobiveil_pcie *pcie) {
> > > u32 value, pab_ctrl, type;
> > > struct resource_entry *win;
> > > + int i;
> > > +
> > > + /* Disable all inbound/outbound windows */
> > > + for (i = 0; i < pcie->apio_wins; i++)
> > > + mobiveil_pcie_disable_ob_win(pcie, i);
> > > + for (i = 0; i < pcie->ppio_wins; i++)
> > > + mobiveil_pcie_disable_ib_win(pcie, i);
> > >
> > > /* setup bus numbers */
> > > value = csr_readl(pcie, PCI_PRIMARY_BUS);
> > > --
> > > 2.17.1
> > >

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