Message-ID: <28914007-ee30-636b-eaf4-2180110f589e@linaro.org>
Date:   Fri, 3 Mar 2023 11:37:56 +0100
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Subject: Re: [PATCH 06/16] arm64: dts: exynos: Rename the term elbi to appl
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To:     Shradha Todi <shradha.t@samsung.com>, lpieralisi@kernel.org,
        kw@linux.com, robh@kernel.org, bhelgaas@google.com,
        krzysztof.kozlowski+dt@linaro.org, alim.akhtar@samsung.com,
        jingoohan1@gmail.com, Sergey.Semin@baikalelectronics.ru,
        lukas.bulwahn@gmail.com, hongxing.zhu@nxp.com, tglx@linutronix.de,
        m.szyprowski@samsung.com, jh80.chung@samsung.co,
        pankaj.dubey@samsung.com
Cc:     linux-pci@vger.kernel.org, devicetree@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-samsung-soc@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20230214121333.1837-1-shradha.t@samsung.com>
 <CGME20230214121428epcas5p3d91e877e62a78008d2b0d6066efea059@epcas5p3.samsung.com>
 <20230214121333.1837-7-shradha.t@samsung.com>
 <31e377b7-88bf-8737-0397-44ecca8cff54@linaro.org>
 <139801d94d07$fc0b9e70$f422db50$@samsung.com>
From:   Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
In-Reply-To: <139801d94d07$fc0b9e70$f422db50$@samsung.com>
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On 02/03/2023 14:07, Shradha Todi wrote:
> 
> 
>> -----Original Message-----
>> From: Krzysztof Kozlowski [mailto:krzysztof.kozlowski@linaro.org]
>> Sent: 16 February 2023 16:34
>> To: Shradha Todi <shradha.t@samsung.com>; lpieralisi@kernel.org;
>> kw@linux.com; robh@kernel.org; bhelgaas@google.com;
>> krzysztof.kozlowski+dt@linaro.org; alim.akhtar@samsung.com;
>> jingoohan1@gmail.com; Sergey.Semin@baikalelectronics.ru;
>> lukas.bulwahn@gmail.com; hongxing.zhu@nxp.com; tglx@linutronix.de;
>> m.szyprowski@samsung.com; jh80.chung@samsung.co;
>> pankaj.dubey@samsung.com
>> Cc: linux-pci@vger.kernel.org; devicetree@vger.kernel.org; linux-arm-
>> kernel@lists.infradead.org; linux-samsung-soc@vger.kernel.org; linux-
>> kernel@vger.kernel.org
>> Subject: Re: [PATCH 06/16] arm64: dts: exynos: Rename the term elbi to appl
>>
>> On 14/02/2023 13:13, Shradha Todi wrote:
>>> DT uses the name elbi in reg-names for application logic registers
>>> which is a wrong nomenclature. This patch fixes the same.
>>>
>>> This commit shouldn't be applied without changes
>>> "dt-bindings: PCI: Rename the term elbi to appl" and
>>> "PCI: samsung: Rename the term elbi to appl"
>>
>> Dependencies and patch ordering goes after '---', because there is no point
>> to store it in git history.
>>
> 
> Understood will take care in next set of patches.
> 
>> Anyway, that's an ABI break and Exynos5433 is quite stable, so without clear
>> indication of fixed bug, we should not do this.
>>
> 
> We have strong technical reason to do so.
> 
> As per DWC PCIe UM, ELBI delivers an inbound register RD/WR received by the controller to external application registers when the controller
> is expected to generate the PCIe completion of this register RD/WR.
> In this driver register space which is currently marked as ELBI, is not used for this purpose (Not sure why original author has named this set of registers as ELBI)
> So to keep this technically correct, it should be marked as application specific wrapper register space.
> We used name as "appl" taking reference from intel-gw-pcie.yaml's similar register space named as "app", whereas in nvidia,tegra194-pcie.yaml it's named "appl". 
> 
> So our argument is if a future Samsung manufactured SoC having DWC PCIe controller comes with support of real ELBI interface, we need to use the name elbi.
> We know such SoC exists but they are not yet upstreamed.
> 
> Ready to adopt the best possible suggested method to make this happen but I really think the name ELBI is misleading.

All this is rather reason for a future case. What is the problem
experienced now?

Best regards,
Krzysztof