linux-kernel - Re: [PATCH v4 2/5] PCI: designware-ep: Make dw_pcie_ep_set

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Message-ID: <e779a6dc-3037-69da-1e92-64c5d8348019@ti.com>
Date:   Wed, 21 Mar 2018 11:19:57 +0530
From:   Kishon Vijay Abraham I <kishon@...com>
To:     Niklas Cassel <niklas.cassel@...s.com>,
        Jingoo Han <jingoohan1@...il.com>,
        Joao Pinto <Joao.Pinto@...opsys.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
CC:     Niklas Cassel <niklass@...s.com>, <linux-pci@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 2/5] PCI: designware-ep: Make dw_pcie_ep_set_bar()
 handle 64-bit BARs properly

Hi Niklas,

On Thursday 08 March 2018 07:03 PM, Niklas Cassel wrote:
> Since a 64-bit BAR consists of a BAR pair, we need to write to both
> BARs in the BAR pair to setup the BAR properly.
> 
> Signed-off-by: Niklas Cassel <niklas.cassel@...s.com>
> ---
>  drivers/pci/dwc/pcie-designware-ep.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/dwc/pcie-designware-ep.c b/drivers/pci/dwc/pcie-designware-ep.c
> index 9236b998327f..946bbdf53c4d 100644
> --- a/drivers/pci/dwc/pcie-designware-ep.c
> +++ b/drivers/pci/dwc/pcie-designware-ep.c
> @@ -136,8 +136,15 @@ static int dw_pcie_ep_set_bar(struct pci_epc *epc, u8 func_no,
>  		return ret;
>  
>  	dw_pcie_dbi_ro_wr_en(pci);
> -	dw_pcie_writel_dbi2(pci, reg, size - 1);
> -	dw_pcie_writel_dbi(pci, reg, flags);
> +	if (flags & PCI_BASE_ADDRESS_MEM_TYPE_64) {
> +		dw_pcie_writel_dbi2(pci, reg, lower_32_bits(size - 1));
> +		dw_pcie_writel_dbi(pci, reg, flags);
> +		dw_pcie_writel_dbi2(pci, reg + 4, upper_32_bits(size - 1));
> +		dw_pcie_writel_dbi(pci, reg + 4, 0);

I think we should check in pci_epc_set_bar to make sure BAR_5 cannot have
PCI_BASE_ADDRESS_MEM_TYPE_64 flag set as this might lead undesired result.

Thanks
Kishon