RE: [PATCHv5 18/20] PCI: mobiveil: Disable IB and OB windows set by bootloader

[Z.q. Hou]

Hi Lorenzo,


> -----Original Message-----
> From: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
> Sent: 2019å6æ17æ 17:31
> To: Z.q. Hou <zhiqiang.hou@xxxxxxx>
> Cc: bhelgaas@xxxxxxxxxx; linux-pci@xxxxxxxxxxxxxxx;
> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx;
> linux-kernel@xxxxxxxxxxxxxxx; robh+dt@xxxxxxxxxx; mark.rutland@xxxxxxx;
> l.subrahmanya@xxxxxxxxxxxxxx; shawnguo@xxxxxxxxxx; Leo Li
> <leoyang.li@xxxxxxx>; catalin.marinas@xxxxxxx; will.deacon@xxxxxxx;
> Mingkai Hu <mingkai.hu@xxxxxxx>; M.h. Lian <minghuan.lian@xxxxxxx>;
> Xiaowei Bao <xiaowei.bao@xxxxxxx>
> Subject: Re: [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@xxxxxxx]
> > > Sent: 2019å6æ13æ 0:24
> > > To: Z.q. Hou <zhiqiang.hou@xxxxxxx>; bhelgaas@xxxxxxxxxx
> > > Cc: linux-pci@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx;
> > > devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> > > robh+dt@xxxxxxxxxx; mark.rutland@xxxxxxx;
> > > robh+l.subrahmanya@xxxxxxxxxxxxxx;
> > > shawnguo@xxxxxxxxxx; Leo Li <leoyang.li@xxxxxxx>;
> > > catalin.marinas@xxxxxxx; will.deacon@xxxxxxx; Mingkai Hu
> > > <mingkai.hu@xxxxxxx>; M.h. Lian <minghuan.lian@xxxxxxx>; Xiaowei
> Bao
> > > <xiaowei.bao@xxxxxxx>
> > > 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@xxxxxxx>
> > > >
> > > > 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.

This patch is just to avoid uboot driver windows setup and Linux driver windows
setup overlap issue, please drop it if you don't think it's needed ð.

Thanks,
Zhiqiang

> 
> > > 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@xxxxxxx>
> > > > Reviewed-by: Minghuan Lian <Minghuan.Lian@xxxxxxx>
> > > > Reviewed-by: Subrahmanya Lingappa <l.subrahmanya@xxxxxxxxxxxxxx>
> > > > ---
> > > > 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
> > > >