linux-kernel - Re: [RESEND PATCH v3 4/7] PCI: dwc: all: Modify dbi accessors to take dbi

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <58C2A28C.60703@ti.com>
Date:   Fri, 10 Mar 2017 18:26:44 +0530
From:   Kishon Vijay Abraham I <kishon@...com>
To:     Niklas Cassel <niklas.cassel@...s.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Joao Pinto <Joao.Pinto@...opsys.com>,
        <linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-omap@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>
CC:     <nsekhar@...com>, Jingoo Han <jingoohan1@...il.com>,
        Richard Zhu <hongxing.zhu@....com>,
        Lucas Stach <l.stach@...gutronix.de>,
        Murali Karicheri <m-karicheri2@...com>,
        Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
        Jesper Nilsson <jespern@...s.com>,
        Zhou Wang <wangzhou1@...ilicon.com>,
        Gabriele Paoloni <gabriele.paoloni@...wei.com>
Subject: Re: [RESEND PATCH v3 4/7] PCI: dwc: all: Modify dbi accessors to take
 dbi_base as argument

Hi Niklas,

On Friday 10 March 2017 06:01 PM, Niklas Cassel wrote:
> On 03/10/2017 12:36 PM, Kishon Vijay Abraham I wrote:
>> Hi,
>>
>> On Thursday 09 March 2017 08:35 PM, Niklas Cassel wrote:
>>>
>>> On 03/09/2017 03:48 PM, Niklas Cassel wrote:
>>>> On 03/09/2017 07:39 AM, Kishon Vijay Abraham I wrote:
>>>>> dwc has 2 dbi address space labeled dbics and dbics2. The existing
>>>>> helper to access dbi address space can access only dbics. However
>>>>> dbics2 has to be accessed for programming the BAR registers in the
>>>>> case of EP mode. This is in preparation for adding EP mode support
>>>>> to dwc driver.
>>>> Hello Kishon
>>>>
>>>> I don't really like the idea of adding an extra argument to every existing read/write.
>>>> Will not a read/write using dbi2 be quite uncommon compared to a read/write
>>>> using dbi?
>>>>
>>>> How about something like this:
>>>>
>>>> void __dw_pcie_writel(struct dw_pcie *pci, void __iomem *base, u32 reg, u32 val)
>>>> {
>>>>     if (pci->ops->writel_dbi)
>>>>         pci->ops->writel_dbi(pci, base, reg, val);
>>>>     else
>>>>         writel(val, base + reg);
>>>> }
>>>>
>>>> #define dw_pcie_writel_dbi(pci, reg, val) __dw_pcie_writel(pci, pci->dbi_base, reg, val)
>>>> #define dw_pcie_writel_dbi2(pci, reg, val) __dw_pcie_writel(pci, pci->dbi_base2, reg, val)
>>> Perhaps make dw_pcie_writel_dbi2 a function rather than a define,
>>> so we can return an error if pci->dbi_base2 == NULL.
>> Should we return an error? We don't return error for dbi_base either. I think
>> it should be sufficient to return errors while populating dbi_base or
>> dbi_base2. Otherwise it's a bug and should result in abort. Joao?
> 
> Sorry for previous empty email.
> 
> 
> What I meant to write:
> 
> Right now we do error checking for dbi_base in platform specific code
> and in pcie-designware-host.c:dw_pcie_host_init.

it's been done in dw_pcie_host_init not as an error checking but since it's
*optional* for certain platforms to populate dbi_base (i.e where dbi_base is
mapped to configuration space), host_init takes care of assigning dbi_base to
configuration space address.

Thanks
Kishon