[PATCH v4 6/6] PCI: layerscape: add ls_pcie_msi_host_init

[Lian M.H.]

Hi Bjorn,

I am so sorry about text code setting. Now, I carefully checked the mail configuration again, hope it is ok.
I greatly appreciate your review and comments.

Thanks,
Minghuan

> -----Original Message-----
> From: Bjorn Helgaas [mailto:helgaas at kernel.org]
> Sent: Tuesday, November 03, 2015 5:07 AM
> To: Lian Minghuan-B31939 <Minghuan.Lian at freescale.com>
> Cc: linux-pci at vger.kernel.org; linux-arm-kernel at lists.infradead.org; Zang
> Roy-R61911 <tie-fei.zang at freescale.com>; Hu Mingkai-B21284
> <Mingkai.Hu at freescale.com>; Yoder Stuart-B08248
> <stuart.yoder at freescale.com>; Li Yang-Leo-R58472 <LeoLi at freescale.com>;
> Arnd Bergmann <arnd at arndb.de>; Bjorn Helgaas <bhelgaas at google.com>;
> Jingoo Han <jg1.han at samsung.com>; Zhou Wang
> <wangzhou1 at hisilicon.com>; Thomas Gleixner <tglx at linutronix.de>
> Subject: Re: [PATCH v4 6/6] PCI: layerscape: add ls_pcie_msi_host_init
> 
> Your reply was *still* base64-encoded and thus rejected by the vger mailing
> lists.
> 
> Minghuan wrote:
> > On Thu, Oct 22, 2015 at 11:21:30AM -0500, Bjorn Helgaas wrote:
> > > Minghuan wrote:
> > > > On Wed, Oct 21, 2015 at 04:34:16PM -0500, Bjorn Helgaas wrote:
> > > > > Hi Minghuan,
> > > > >
> > > > > On Fri, Oct 16, 2015 at 03:19:20PM +0800, Minghuan Lian wrote:
> > > > > > Layerscape PCIe has its own MSI implementation. The patch
> > > > > > registers
> > > > > > ls_pcie_msi_host_init() to avoid using Designware's MSI.
> > > > > >
> > > > > > Signed-off-by: Minghuan Lian <Minghuan.Lian at freescale.com>
> > > > > > ---
> > > > > > Change log
> > > > > > v4: split from [PATCH v3] PCI: layerscape: Add PCIe support
> > > > > > for LS1043a and LS2080a
> > > > > >
> > > > > >  drivers/pci/host/pci-layerscape.c | 17 +++++++++++++++++
> > > > > >  1 file changed, 17 insertions(+)
> > > > > >
> > > > > > diff --git a/drivers/pci/host/pci-layerscape.c
> > > > > > b/drivers/pci/host/pci-layerscape.c
> > > > > > index c53692a..8fac6c8 100644
> > > > > > --- a/drivers/pci/host/pci-layerscape.c
> > > > > > +++ b/drivers/pci/host/pci-layerscape.c
> > > > > > @@ -150,14 +150,31 @@ static void ls_pcie_host_init(struct
> pcie_port *pp)
> > > > > >  	iowrite32(0, pcie->dbi + PCIE_DBI_RO_WR_EN);  }
> > > > > >
> > > > > > +static int ls_pcie_msi_host_init(struct pcie_port *pp,
> > > > > > +				 struct msi_controller *chip) {
> > > > > > +	struct device_node *msi_node;
> > > > > > +	struct device_node *np = pp->dev->of_node;
> > > > > > +
> > > > > > +	msi_node = of_parse_phandle(np, "msi-parent", 0);
> > > > > > +	if (!msi_node) {
> > > > > > +		dev_err(pp->dev, "failed to find msi-parent\n");
> > > > > > +		return -EINVAL;
> > > > > > +	}
> > > > > > +
> > > > > > +	return 0;
> > > > >
> > > > > I don't see how this can be right.  I think it's OK if you want
> > > > > to enforce the presence of "msi-parent", but the other
> > > > > implementations of .msi_host_init (ks_dw_pcie_msi_host_init()
> > > > > and the default implementation in dw_pcie_host_init()) both set
> > > > > pp->irq_domain and call irq_create_mapping().
> > > > >
> > > > > You don't do either of those, so I don't see how MSIs can work,
> > > > > because I assume the generic DesignWare code will depend on
> > > > > pp->irq_domain.  If you're planning to add more
> > > > > Layerscape-specific MSI support later, I think you should wait and
> include this patch with that work.
> > >
> > > > Regarding MSI, both LS1021a and LS1043a use SCFG to implement it. I
> have submitted patch:
> > > > https://patchwork.kernel.org/patch/7411131/
> > > > https://patchwork.kernel.org/patch/7411141/
> > >
> > > > While ls2085a use ITS for it, we just re-use the ITS driver.
> > >
> > > > I notice some platform MSI driver files were placed in pci/host
> > > > folder not irqchip.  If it is ok, I would like to change driver
> > > > folder and re-submitted the MSI patch.
> > >
> > > I suppose you're referring to drivers/pci/host/pci-xgene-msi.c.
> > > That file doesn't really have much PCI stuff in it.  It does call
> > > pci_msi_create_irq_domain(), but that's really the only PCI
> > > interface or data structure it uses.  So I don't know if
> > > drivers/pci/host or drivers/irqchip is the best place for it and for
> > > your irq-ls-scfg-msi.c.
> > >
> > > The connection between pci-xgene-msi.c and pci-xgene.c is not very
> > > clear to me, and that's sort of what I'm complaining about here.
> > > You're overriding a default MSI initialization method.  Usually that
> > > means you do the same thing as the default method, but in a
> > > different way.  You aren't doing the same thing at all, which makes
> > > the code hard to review.
> > >
> > > Maybe a comment about how the MSI controller gets connected to
> > > devices below this host bridge would be enough.
> 
> > 1. We need to define callback function msi_host_init() to avoid the
> > running desginware MSI related code Because our PCIe controller do not
> > enable this feature.
> >
> > 2. we do not need to do anything such as bus->msi= ls_scfg_msi Because
> > with the latest code, when PCIe controller device is created
> > of_msi_configure() will be called and MSI domain pointed by
> > 'msi-parent' will be bound  to the device. pci_msi_get_domain(struct
> > pci_dev *dev) -> dev_get_msi_domain(&dev->dev) will return this MSI
> > domain.
> >
> > 3. I will add a comment in the next version.
> 
> Don't bother, I added a comment and applied the patch like this:
> 
> 
> commit 90cbdf8412d206f65ece3dcc53230e673da569c6
> Author: Minghuan Lian <Minghuan.Lian at freescale.com>
> Date:   Fri Oct 16 15:19:20 2015 +0800
> 
>     PCI: layerscape: Add ls_pcie_msi_host_init()
> 
>     Layerscape PCIe has its own MSI implementation.
> 
>     Register ls_pcie_msi_host_init() to avoid using DesignWare's MSI.
> 
>     [bhelgaas: add comment]
>     Signed-off-by: Minghuan Lian <Minghuan.Lian at freescale.com>
>     Signed-off-by: Bjorn Helgaas <bhelgaas at google.com>
> 
> diff --git a/drivers/pci/host/pci-layerscape.c b/drivers/pci/host/pci-layerscape.c
> index 6a9fa8a..1677890 100644
> --- a/drivers/pci/host/pci-layerscape.c
> +++ b/drivers/pci/host/pci-layerscape.c
> @@ -150,14 +150,37 @@ static void ls_pcie_host_init(struct pcie_port *pp)
>  	iowrite32(0, pcie->dbi + PCIE_DBI_RO_WR_EN);  }
> 
> +static int ls_pcie_msi_host_init(struct pcie_port *pp,
> +				 struct msi_controller *chip)
> +{
> +	struct device_node *msi_node;
> +	struct device_node *np = pp->dev->of_node;
> +
> +	/*
> +	 * The MSI domain is set by the generic of_msi_configure().  This
> +	 * .msi_host_init() function keeps us from doing the default MSI
> +	 * domain setup in dw_pcie_host_init() and also enforces the
> +	 * requirement that "msi-parent" exists.
> +	 */
> +	msi_node = of_parse_phandle(np, "msi-parent", 0);
> +	if (!msi_node) {
> +		dev_err(pp->dev, "failed to find msi-parent\n");
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
>  static struct pcie_host_ops ls1021_pcie_host_ops = {
>  	.link_up = ls1021_pcie_link_up,
>  	.host_init = ls1021_pcie_host_init,
> +	.msi_host_init = ls_pcie_msi_host_init,
>  };
> 
>  static struct pcie_host_ops ls_pcie_host_ops = {
>  	.link_up = ls_pcie_link_up,
>  	.host_init = ls_pcie_host_init,
> +	.msi_host_init = ls_pcie_msi_host_init,
>  };
> 
>  static struct ls_pcie_drvdata ls1021_drvdata = {