linux-kernel - Re: [PATCH 1/2] PCI: dwc: Add support to handle prefetchable memory separately

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Message-ID: <20200729185654.GA585891@bogus>
Date:   Wed, 29 Jul 2020 12:56:54 -0600
From:   Rob Herring <robh@...nel.org>
To:     Vidya Sagar <vidyas@...dia.com>
Cc:     jingoohan1@...il.com, gustavo.pimentel@...opsys.com,
        lorenzo.pieralisi@....com, bhelgaas@...gle.com,
        amurray@...goodpenguin.co.uk, thierry.reding@...il.com,
        jonathanh@...dia.com, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, kthota@...dia.com,
        mmaddireddy@...dia.com, sagar.tv@...il.com
Subject: Re: [PATCH 1/2] PCI: dwc: Add support to handle prefetchable memory
 separately

On Tue, Jun 02, 2020 at 03:39:39PM +0530, Vidya Sagar wrote:
> Add required structure members to struct pcie_port to handle prefetchable
> memory aperture separately from non-prefetchable memory aperture so that
> any dependency on the order of their appearance in the 'ranges' property
> of the respective PCIe device tree node can be removed.
> 
> Signed-off-by: Vidya Sagar <vidyas@...dia.com>
> ---
>  .../pci/controller/dwc/pcie-designware-host.c | 26 ++++++++++++-------
>  drivers/pci/controller/dwc/pcie-designware.h  |  4 +++
>  2 files changed, 21 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> index 42fbfe2a1b8f..6f06d6bd9f00 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> @@ -363,13 +363,23 @@ int dw_pcie_host_init(struct pcie_port *pp)
>  			pp->io_base = pci_pio_to_address(pp->io->start);
>  			break;
>  		case IORESOURCE_MEM:
> -			pp->mem = win->res;
> -			pp->mem->name = "MEM";
> -			mem_size = resource_size(pp->mem);
> -			if (upper_32_bits(mem_size))
> -				dev_warn(dev, "MEM resource size exceeds max for 32 bits\n");
> -			pp->mem_size = mem_size;
> -			pp->mem_bus_addr = pp->mem->start - win->offset;
> +			if (win->res->flags & IORESOURCE_PREFETCH) {
> +				pp->prefetch = win->res;
> +				pp->prefetch->name = "PREFETCH";
> +				pp->prefetch_base = pp->prefetch->start;
> +				pp->prefetch_size = resource_size(pp->prefetch);
> +				pp->perfetch_bus_addr = pp->prefetch->start -
> +							win->offset;
> +			} else {
> +				pp->mem = win->res;
> +				pp->mem->name = "MEM";
> +				pp->mem_base = pp->mem->start;
> +				mem_size = resource_size(pp->mem);
> +				if (upper_32_bits(mem_size))
> +					dev_warn(dev, "MEM resource size exceeds max for 32 bits\n");
> +				pp->mem_size = mem_size;
> +				pp->mem_bus_addr = pp->mem->start - win->offset;
> +			}
>  			break;
>  		case 0:
>  			pp->cfg = win->res;
> @@ -394,8 +404,6 @@ int dw_pcie_host_init(struct pcie_port *pp)
>  		}
>  	}
>  
> -	pp->mem_base = pp->mem->start;
> -
>  	if (!pp->va_cfg0_base) {
>  		pp->va_cfg0_base = devm_pci_remap_cfgspace(dev,
>  					pp->cfg0_base, pp->cfg0_size);
> diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> index 656e00f8fbeb..c87c1b2a1177 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.h
> +++ b/drivers/pci/controller/dwc/pcie-designware.h
> @@ -186,9 +186,13 @@ struct pcie_port {
>  	u64			mem_base;
>  	phys_addr_t		mem_bus_addr;
>  	u32			mem_size;
> +	u64			prefetch_base;
> +	phys_addr_t		perfetch_bus_addr;
> +	u64			prefetch_size;

There's no reason to store these for all eternity as they are used in 
one place and already stored as resources in bridge->windows.

I have a patch series removing most of this that I will post in a few 
days. There's a WIP branch, pci-dw-config-access, in my kernel.org 
tree. Mostly you just need the bridge ptr which is isn't currently 
saved in pcie_port.

Rob