linux-kernel - Re: [Patch v5 1/4] memory: tegra: Add memory controller channels support

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Message-ID: <349166ad-7bcc-c550-8636-8342eb098333@nvidia.com>
Date:   Wed, 30 Mar 2022 10:37:07 +0530
From:   Ashish Mhetre <amhetre@...dia.com>
To:     Dmitry Osipenko <dmitry.osipenko@...labora.com>,
        Dmitry Osipenko <digetx@...il.com>,
        krzysztof.kozlowski@...onical.com, robh+dt@...nel.org,
        thierry.reding@...il.com, jonathanh@...dia.com,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        linux-tegra@...r.kernel.org
Cc:     vdumpa@...dia.com, Snikam@...dia.com
Subject: Re: [Patch v5 1/4] memory: tegra: Add memory controller channels
 support



On 3/30/2022 5:18 AM, Dmitry Osipenko wrote:
> External email: Use caution opening links or attachments
> 
> 
> On 3/25/22 07:50, Ashish Mhetre wrote:
>>
>>
>> On 3/19/2022 9:12 PM, Dmitry Osipenko wrote:
>>> External email: Use caution opening links or attachments
>>>
>>>
>>> 16.03.2022 12:25, Ashish Mhetre пишет:
>>>>   From tegra186 onwards, memory controller support multiple channels.
>>>> Add support for mapping address spaces of these channels.
>>>> Make sure that number of channels are as expected on each SOC.
>>>> During error interrupts from memory controller, appropriate registers
>>>> from these channels need to be accessed for logging error info.
>>>>
>>>> Signed-off-by: Ashish Mhetre <amhetre@...dia.com>
>>>> ---
>>>>    drivers/memory/tegra/mc.c       |  6 ++++
>>>>    drivers/memory/tegra/tegra186.c | 52 +++++++++++++++++++++++++++++++++
>>>>    drivers/memory/tegra/tegra194.c |  1 +
>>>>    drivers/memory/tegra/tegra234.c |  1 +
>>>>    include/soc/tegra/mc.h          |  7 +++++
>>>>    5 files changed, 67 insertions(+)
>>>>
>>>> diff --git a/drivers/memory/tegra/mc.c b/drivers/memory/tegra/mc.c
>>>> index bf3abb6d8354..3cda1d9ad32a 100644
>>>> --- a/drivers/memory/tegra/mc.c
>>>> +++ b/drivers/memory/tegra/mc.c
>>>> @@ -749,6 +749,12 @@ static int tegra_mc_probe(struct platform_device
>>>> *pdev)
>>>>         if (IS_ERR(mc->regs))
>>>>                 return PTR_ERR(mc->regs);
>>>>
>>>> +     if (mc->soc->ops && mc->soc->ops->map_regs) {
>>>> +             err = mc->soc->ops->map_regs(mc, pdev);
>>>> +             if (err < 0)
>>>> +                     return err;
>>>> +     }
>>>> +
>>>>         mc->debugfs.root = debugfs_create_dir("mc", NULL);
>>>>
>>>>         if (mc->soc->ops && mc->soc->ops->probe) {
>>>> diff --git a/drivers/memory/tegra/tegra186.c
>>>> b/drivers/memory/tegra/tegra186.c
>>>> index 3d153881abc1..a8a45e6ff1f1 100644
>>>> --- a/drivers/memory/tegra/tegra186.c
>>>> +++ b/drivers/memory/tegra/tegra186.c
>>>> @@ -139,11 +139,62 @@ static int tegra186_mc_probe_device(struct
>>>> tegra_mc *mc, struct device *dev)
>>>>         return 0;
>>>>    }
>>>>
>>>> +static int tegra186_mc_map_regs(struct tegra_mc *mc,
>>>> +                             struct platform_device *pdev)
>>>> +{
>>>> +     struct device_node *np = pdev->dev.parent->of_node;
>>>> +     int num_dt_channels, reg_cells = 0;
>>>> +     struct resource *res;
>>>> +     int i, ret;
>>>> +     u32 val;
>>>> +
>>>> +     ret = of_property_read_u32(np, "#address-cells", &val);
>>>> +     if (ret) {
>>>> +             dev_err(&pdev->dev, "missing #address-cells property\n");
>>>> +             return ret;
>>>> +     }
>>>> +
>>>> +     reg_cells = val;
>>>> +
>>>> +     ret = of_property_read_u32(np, "#size-cells", &val);
>>>> +     if (ret) {
>>>> +             dev_err(&pdev->dev, "missing #size-cells property\n");
>>>> +             return ret;
>>>> +     }
>>>> +
>>>> +     reg_cells += val;
>>>> +
>>>> +     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\n");
>>>
>>> Update what?
>>>
>>>> +             return 0;
>>>> +     }
>>>> +
>>>> +     mc->mcb_regs = devm_platform_get_and_ioremap_resource(pdev, 1,
>>>> &res);
>>>
>>> Can't we name each reg bank individually in the DT and then use
>>> devm_platform_ioremap_resource_byname()?
>>>
>> That can be done but I think current logic will be better as we can
>> simply ioremap them by running in loop and assigning the mc_regs array.
>> Otherwise there will be like 17 ioremap_byname() individual calls for
>> Tegra194 and Tegra234.
>> Will it be fine having that many ioremap_byname() calls?
>> Also, Tegra186 has 5 channels which are less than Tegra194 and Tegra234.
>> If we go with ioremap_byname() then we'll have to differentiate number
>> of ioremap_byname() calls.
> for (i = 0; i < mc->soc->num_channels; i++) {
>          sprintf(name, "mc%u", i);
>          err = devm_platform_ioremap_resource_byname(dev, name);
>          ...
> }

Okay, for this reg banks should be named "mc0", "mc1", and so on.
I will update this in v6.