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Message-ID: <0d644682-094d-6151-aa2f-86552c8f9a87@codethink.co.uk>
Date:   Thu, 28 Jul 2022 16:31:17 +0100
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Subject: Re: [PATCH RESEND v4 03/15] PCI: dwc: Convert to using native IP-core
 versions representation
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To:     Bjorn Helgaas <helgaas@kernel.org>,
        Serge Semin <Sergey.Semin@baikalelectronics.ru>
Cc:     Rob Herring <robh@kernel.org>, Bjorn Helgaas <bhelgaas@google.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Jingoo Han <jingoohan1@gmail.com>,
        Gustavo Pimentel <gustavo.pimentel@synopsys.com>,
        Lorenzo Pieralisi <lpieralisi@kernel.org>,
        =?UTF-8?Q?Krzysztof_Wilczy=c5=84ski?= <kw@linux.com>,
        Rahul Tanwar <rtanwar@maxlinear.com>,
        Thierry Reding <thierry.reding@gmail.com>,
        Jonathan Hunter <jonathanh@nvidia.com>,
        Serge Semin <fancer.lancer@gmail.com>,
        Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>,
        Pavel Parkhomenko <Pavel.Parkhomenko@baikalelectronics.ru>,
        Frank Li <Frank.Li@nxp.com>,
        Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
        Rob Herring <robh+dt@kernel.org>, linux-pci@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-tegra@vger.kernel.org
References: <20220728152418.GA302516@bhelgaas>
From:   Ben Dooks <ben.dooks@codethink.co.uk>
Organization: Codethink Limited.
In-Reply-To: <20220728152418.GA302516@bhelgaas>
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On 28/07/2022 16:24, Bjorn Helgaas wrote:
> On Fri, Jun 24, 2022 at 05:39:35PM +0300, Serge Semin wrote:
>> Since DWC PCIe v4.70a the controller version can be read from the
>> PORT_LOGIC.PCIE_VERSION_OFF register. Version is represented in the FourCC
>> format [1]. It's standard versioning approach for the Synopsys DWC
>> IP-cores. Moreover some of the DWC kernel drivers already make use of it
>> to fixup version-dependent functionality (See DWC USB3, Stmicro STMMAC or
>> recent DW SPI driver).
> 
> These references to other drivers might be useful, but without a
> function name or file name, I can't easily find them.
> 
>> In order to preserve the standard version
>> representation and prevent the data conversion back and forth, we suggest
>> to preserve the native version representation in the DWC PCIe driver too
>> in the same way as it has already been done in the rest of the DWC
>> drivers. IP-core version reading from the CSR will be introduced in the
>> next commit together with a simple macro-based API to use it.
>>
>> [1] https://en.wikipedia.org/wiki/FourCC
> 

I'm currently looking at a OF based dw-apb-timers-pwm driver, so also
would like to follow this.

-- 
Ben Dooks				http://www.codethink.co.uk/
Senior Engineer				Codethink - Providing Genius

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