linux-kernel - Re: [PATCH v4 5/6] PCI: rcar: Add support for rcar PCIe controller in endpoint mode

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Date:   Tue, 11 Feb 2020 20:42:39 -0700
From:   Nathan Chancellor <natechancellor@...il.com>
To:     Lad Prabhakar <prabhakar.csengg@...il.com>
Cc:     Bjorn Helgaas <bhelgaas@...gle.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Kishon Vijay Abraham I <kishon@...com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jingoo Han <jingoohan1@...il.com>,
        Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
        Marek Vasut <marek.vasut+renesas@...il.com>,
        Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
        Shawn Lin <shawn.lin@...k-chips.com>,
        Heiko Stuebner <heiko@...ech.de>,
        Andrew Murray <andrew.murray@....com>,
        linux-pci@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-renesas-soc@...r.kernel.org,
        linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org,
        Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
        clang-built-linux@...glegroups.com
Subject: Re: [PATCH v4 5/6] PCI: rcar: Add support for rcar PCIe controller
 in endpoint mode

Hi Lad,

On Sat, Feb 08, 2020 at 06:36:40PM +0000, Lad Prabhakar wrote:
> This patch adds support for rcar PCIe controller to work in endpoint mode.
> 
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> ---
>  drivers/pci/controller/Kconfig        |   7 +
>  drivers/pci/controller/Makefile       |   1 +
>  drivers/pci/controller/pcie-rcar-ep.c | 492 ++++++++++++++++++++++++++++++++++
>  drivers/pci/controller/pcie-rcar.h    |   6 +
>  4 files changed, 506 insertions(+)
>  create mode 100644 drivers/pci/controller/pcie-rcar-ep.c
> 

<snip>

> diff --git a/drivers/pci/controller/pcie-rcar-ep.c b/drivers/pci/controller/pcie-rcar-ep.c
> new file mode 100644
> index 0000000..32a7fca
> --- /dev/null
> +++ b/drivers/pci/controller/pcie-rcar-ep.c

<snip>

> +static int rcar_pcie_ep_set_bar(struct pci_epc *epc, u8 func_no,
> +				struct pci_epf_bar *epf_bar)
> +{
> +	struct rcar_pcie *ep = epc_get_drvdata(epc);
> +	dma_addr_t cpu_addr = epf_bar->phys_addr;
> +	int flags = epf_bar->flags | LAR_ENABLE | LAM_64BIT;
> +	enum pci_barno bar = epf_bar->barno;
> +	u64 size = 1ULL << fls64(epf_bar->size - 1);
> +	u32 mask;
> +	int idx;
> +	int err;
> +
> +	idx = find_first_zero_bit(ep->ib_window_map, ep->num_ib_windows);
> +	if (idx >= ep->num_ib_windows) {
> +		dev_err(ep->dev, "no free inbound window\n");
> +		return -EINVAL;
> +	}
> +
> +	if ((flags & PCI_BASE_ADDRESS_SPACE) == PCI_BASE_ADDRESS_SPACE_IO)
> +		flags |= IO_SPACE;
> +
> +	ep->bar_to_atu[bar] = idx;
> +	/* use 64 bit bars */
> +	set_bit(idx, ep->ib_window_map);
> +	set_bit(idx + 1, ep->ib_window_map);
> +
> +	if (cpu_addr > 0) {
> +		unsigned long nr_zeros = __ffs64(cpu_addr);
> +		u64 alignment = 1ULL << nr_zeros;
> +
> +		size = min(size, alignment);
> +	} else {
> +		size = size;
> +	}

We received a report from the 0day bot that clang warns that this is
unnecessary. Would you mind removing it if you have to spin up a new
version?

You can view the full report here:

https://groups.google.com/d/msg/clang-built-linux/KHUKw5L8yxw/Mb7KRMG7BQAJ

Cheers,
Nathan