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Date: Mon, 26 Oct 2020 10:40:48 -0500
From: Rob Herring <robh@...nel.org>
To: Vidya Sagar <vidyas@...dia.com>
Cc: Jingoo Han <jingoohan1@...il.com>,
Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Andrew Murray <amurray@...goodpenguin.co.uk>,
Thierry Reding <treding@...dia.com>,
Jon Hunter <jonathanh@...dia.com>,
PCI <linux-pci@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
kthota@...dia.com, Manikanta Maddireddy <mmaddireddy@...dia.com>,
sagar.tv@...il.com
Subject: Re: [PATCH 3/3] PCI: dwc: Add support to handle prefetchable memory mapping
On Fri, Oct 23, 2020 at 2:57 PM Vidya Sagar <vidyas@...dia.com> wrote:
>
> DWC sub-system currently doesn't differentiate between prefetchable and
> non-prefetchable memory aperture entries in the 'ranges' property and
> provides ATU mapping only for the first memory aperture entry out of all
> the entries present. This was introduced by the
> commit 0f71c60ffd26 ("PCI: dwc: Remove storing of PCI resources").
> Mapping for a memory apreture is required if its CPU address and the bus
> address are different and the current mechanism works only if the memory
> aperture which needs mapping happens to be the first entry. It doesn't
> work either if the memory aperture that needs mapping is not the first
> entry or if both prefetchable and non-prefetchable apertures need mapping.
>
> This patch fixes this issue by differentiating between prefetchable and
> non-prefetchable apertures in the 'ranges' property there by removing the
> dependency on the order in which they are specified and adds support for
> mapping prefetchable aperture using ATU region-3 if required.
>
> Fixes: 0f71c60ffd26 ("PCI: dwc: Remove storing of PCI resources")
Fixes should come first, then new features.
> Link: http://patchwork.ozlabs.org/project/linux-pci/patch/20200513190855.23318-1-vidyas@nvidia.com/
'Link' is the link for this message and should be a lore.kernel.org
link. Maintainers will add it.
>
> Signed-off-by: Vidya Sagar <vidyas@...dia.com>
> ---
> Changes from previous versions:
> * Addressed Rob's comments and as part of that split the patch into three sub-patches
> * Rewrote commit subject and description
> * Addressed review comments from Lorenzo
>
> .../pci/controller/dwc/pcie-designware-host.c | 39 ++++++++++++++++---
> drivers/pci/controller/dwc/pcie-designware.h | 1 +
> 2 files changed, 34 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> index 674f32db85ca..a1f319ccd816 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> @@ -529,9 +529,39 @@ static struct pci_ops dw_pcie_ops = {
> .write = pci_generic_config_write,
> };
>
> +static void dw_pcie_setup_mem_atu(struct pcie_port *pp,
> + struct resource_entry *win)
> +{
> + struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> +
> + /* Check for prefetchable memory aperture */
> + if (win->res->flags & IORESOURCE_PREFETCH) {
> + /* Number of view ports must at least be 4 to enable mapping */
> + if (pci->num_viewport < 4) {
> + dev_warn(pci->dev,
> + "Insufficient ATU regions to map Prefetchable memory\n");
> + } else {
> + dw_pcie_prog_outbound_atu(pci,
> + PCIE_ATU_REGION_INDEX3,
> + PCIE_ATU_TYPE_MEM,
> + win->res->start,
> + win->res->start - win->offset,
> + resource_size(win->res));
> + }
> + } else { /* Non-prefetchable memory aperture */
> + dw_pcie_prog_outbound_atu(pci,
> + PCIE_ATU_REGION_INDEX0,
> + PCIE_ATU_TYPE_MEM,
> + win->res->start,
> + win->res->start - win->offset,
> + resource_size(win->res));
> + }
> +}
> +
This is in no way a minimal fix. I'll send my proposed fix.
> void dw_pcie_setup_rc(struct pcie_port *pp)
> {
> u32 val, ctrl, num_ctrls;
> + struct resource_entry *win;
> struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
>
> /*
> @@ -586,13 +616,10 @@ void dw_pcie_setup_rc(struct pcie_port *pp)
> * ATU, so we should not program the ATU here.
> */
> if (pp->bridge->child_ops == &dw_child_pcie_ops) {
> - struct resource_entry *entry =
> - resource_list_first_type(&pp->bridge->windows, IORESOURCE_MEM);
> + resource_list_for_each_entry(win, &pp->bridge->windows)
> + if (resource_type(win->res) == IORESOURCE_MEM)
> + dw_pcie_setup_mem_atu(pp, win);
>
> - dw_pcie_prog_outbound_atu(pci, PCIE_ATU_REGION_INDEX0,
> - PCIE_ATU_TYPE_MEM, entry->res->start,
> - entry->res->start - entry->offset,
> - resource_size(entry->res));
> if (pci->num_viewport > 2)
> dw_pcie_prog_outbound_atu(pci, PCIE_ATU_REGION_INDEX2,
> PCIE_ATU_TYPE_IO, pp->io_base,
> diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> index e7f441441db2..21dd06831b50 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.h
> +++ b/drivers/pci/controller/dwc/pcie-designware.h
> @@ -80,6 +80,7 @@
> #define PCIE_ATU_VIEWPORT 0x900
> #define PCIE_ATU_REGION_INBOUND BIT(31)
> #define PCIE_ATU_REGION_OUTBOUND 0
> +#define PCIE_ATU_REGION_INDEX3 0x3
> #define PCIE_ATU_REGION_INDEX2 0x2
> #define PCIE_ATU_REGION_INDEX1 0x1
> #define PCIE_ATU_REGION_INDEX0 0x0
> --
> 2.17.1
>
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