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Message-ID: <0ce65e42-6567-9fd5-d959-3bc5aa0457eb@collabora.com>
Date:   Mon, 11 Apr 2022 09:33:46 +0300
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Subject: Re: [Patch v6 1/4] memory: tegra: Add memory controller channels
 support
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To:     Ashish Mhetre <amhetre@nvidia.com>,
        Dmitry Osipenko <digetx@gmail.com>,
        krzysztof.kozlowski@linaro.org, thierry.reding@gmail.com,
        jonathanh@nvidia.com, robh+dt@kernel.org,
        linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
        linux-tegra@vger.kernel.org, krzysztof.kozlowski+dt@linaro.org
Cc:     vdumpa@nvidia.com, Snikam@nvidia.com
References: <20220406052459.10438-1-amhetre@nvidia.com>
 <20220406052459.10438-2-amhetre@nvidia.com>
 <3bbbffff-6aa3-7068-6f0c-4372d53daf94@gmail.com>
 <ba28886f-be5d-9ab2-41d0-942609934263@nvidia.com>
From:   Dmitry Osipenko <dmitry.osipenko@collabora.com>
In-Reply-To: <ba28886f-be5d-9ab2-41d0-942609934263@nvidia.com>
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On 4/11/22 09:05, Ashish Mhetre wrote:
> 
> 
> On 4/10/2022 7:48 PM, Dmitry Osipenko wrote:
>> External email: Use caution opening links or attachments
>>
>>
>> 06.04.2022 08:24, Ashish Mhetre пишет:
>>> +     num_dt_channels =
>>> of_property_count_elems_of_size(pdev->dev.of_node, "reg",
>>> +                                                       reg_cells *
>>> sizeof(u32));
>>> +     /*
>>> +      * On tegra186 onwards, memory controller support multiple
>>> channels.
>>> +      * Apart from regular memory controller channels, there is one
>>> broadcast
>>> +      * channel and one for stream-id registers.
>>> +      */
>>> +     if (num_dt_channels < mc->soc->num_channels + 2) {
>>> +             dev_warn(&pdev->dev, "MC channels are missing, please
>>> update memory controller DT node with MC channels\n");
>>> +             return 0;
>>> +     }
>>> +
>>> +     mc->bcast_ch_regs = devm_platform_ioremap_resource_byname(pdev,
>>> "mc-broadcast");
>>> +     if (IS_ERR(mc->bcast_ch_regs))
>>> +             return PTR_ERR(mc->bcast_ch_regs);
>>
>> Looks to me that you don't need to use of_property_count_elems_of_size()
>> and could only check the "mc-broadcast" presence to decide whether this
>> is an older DT.
>>
> Now that we are using reg-names in new DT, yes it'd be fine to just
> check mc-broadcast to decide it's a new or old DT.
> 
>> mc->bcast_ch_regs = devm_platform_ioremap_resource_byname(pdev,
>> "broadcast");
>> if (IS_ERR(mc->bcast_ch_regs)) {
>>          dev_warn(&pdev->dev, "Broadcast channel is missing, please
>> update your
>> device-tree\n");
>>          return PTR_ERR(mc->bcast_ch_regs);
>> }
> 
> return 0;
> 
> to avoid DT ABI break, right?

Yes, it should be "return 0".