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Date:   Wed, 15 Apr 2020 18:18:36 +0200
From:   Pali =?utf-8?B?Um9ow6Fy?= <pali@kernel.org>
To:     Jason Cooper <jason@lakedaemon.net>, Andrew Lunn <andrew@lunn.ch>,
        Gregory Clement <gregory.clement@bootlin.com>,
        Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>,
        Rob Herring <robh+dt@kernel.org>,
        Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Andrew Murray <amurray@thegoodpenguin.co.uk>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Remi Pommarel <repk@triplefau.lt>,
        Marek =?utf-8?B?QmVow7pu?= <marek.behun@nic.cz>,
        Tomasz Maciej Nowak <tmn505@gmail.com>,
        Xogium <contact@xogium.me>
Cc:     devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-pci@vger.kernel.org
Subject: Re: [PATCH 8/8] PCI: aardvark: Add FIXME for code which access
 PCIE_CORE_CMD_STATUS_REG
Message-ID: <20200415161836.lqbhr6bona7zmgpt@pali>
References: <20200415160054.951-1-pali@kernel.org>
 <20200415160348.1146-4-pali@kernel.org>
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On Wednesday 15 April 2020 18:03:48 Pali Rohár wrote:
> Register PCIE_CORE_CMD_STATUS_REG is applicable only when aardvark
> controller is configured for Endpoint mode. Which is not the case of
> current kernel driver.
> 
> Signed-off-by: Pali Rohár <pali@kernel.org>
> ---
>  drivers/pci/controller/pci-aardvark.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
> index 6a97a3838098..a1cebc734f2d 100644
> --- a/drivers/pci/controller/pci-aardvark.c
> +++ b/drivers/pci/controller/pci-aardvark.c
> @@ -423,6 +423,12 @@ static void advk_pcie_setup_hw(struct advk_pcie *pcie)
>  		advk_writel(pcie, reg, PCIE_CORE_LINK_CTRL_STAT_REG);
>  	} while (1);
>  
> +	/*
> +	 * FIXME: Following code which access PCIE_CORE_CMD_STATUS_REG register
> +	 *        is suspicious. This register is applicable only when the PCI
> +	 *        controller is configured for Endpoint mode. And not when it
> +	 *        is configured for Root Complex.
> +	 */
>  	reg = advk_readl(pcie, PCIE_CORE_CMD_STATUS_REG);
>  	reg |= PCIE_CORE_CMD_MEM_ACCESS_EN |
>  		PCIE_CORE_CMD_IO_ACCESS_EN |
> -- 
> 2.20.1
> 

Just to note, above code needs to be removed or fixed or properly
commented why is correct and what is doing.

I really do not know, so I'm adding at least FIXME comment to document
suspicious code which may cause unexpected problems.