linux-kernel - Re: [PATCH] bus: unifier-system-bus: Remove open coded "ranges" parsing

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Message-ID: <cabaac65-8717-0dfa-2b4c-c95eb16b5beb@socionext.com>
Date:   Mon, 6 Feb 2023 23:30:49 +0900
From:   Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>
To:     Rob Herring <robh@...nel.org>
Cc:     Masami Hiramatsu <mhiramat@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] bus: unifier-system-bus: Remove open coded "ranges"
 parsing

Hi Rob,

On 2023/02/04 0:06, Rob Herring wrote:
> On Wed, Feb 1, 2023 at 11:50 PM Kunihiko Hayashi
> <hayashi.kunihiko@...ionext.com> wrote:
>>
>> Hi Rob,
>>
>> On 2023/02/02 7:00, Rob Herring wrote:
>>> "ranges" is a standard property and we have common helper functions for
>>> parsing it, so let's use them.
>>>
>>> Signed-off-by: Rob Herring <robh@...nel.org>
>>> ---
>>> Compile tested only!
>>
>> Please fix the driver's name.
>>
>> s/unifier-system-bus/uniphier-system-bus/
> 
> doh!
> 
>>
>>> ---
>>>    drivers/bus/uniphier-system-bus.c | 54 +++++++------------------------
>>>    1 file changed, 11 insertions(+), 43 deletions(-)
>>>
>>> diff --git a/drivers/bus/uniphier-system-bus.c
>>> b/drivers/bus/uniphier-system-bus.c
>>> index f70dedace20b..cb5c89ce7b86 100644
>>> --- a/drivers/bus/uniphier-system-bus.c
>>> +++ b/drivers/bus/uniphier-system-bus.c
>>> @@ -176,10 +176,9 @@ static int uniphier_system_bus_probe(struct
>>> platform_device *pdev)
>>>    {
>>>        struct device *dev = &pdev->dev;
>>>        struct uniphier_system_bus_priv *priv;
>>> -     const __be32 *ranges;
>>> -     u32 cells, addr, size;
>>> -     u64 paddr;
>>> -     int pna, bank, rlen, rone, ret;
>>> +     struct of_range_parser parser;
>>> +     struct of_range range;
>>> +     int ret;
>>>
>>>        priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
>>>        if (!priv)
>>> @@ -191,48 +190,17 @@ static int uniphier_system_bus_probe(struct
>>> platform_device *pdev)
>>>
>>>        priv->dev = dev;
>>>
>>> -     pna = of_n_addr_cells(dev->of_node);
>>> -
>>> -     ret = of_property_read_u32(dev->of_node, "#address-cells",
>>> &cells);
>>> -     if (ret) {
>>> -             dev_err(dev, "failed to get #address-cells\n");
>>> -             return ret;
>>> -     }
>>> -     if (cells != 2) {
>>> -             dev_err(dev, "#address-cells must be 2\n");
>>> -             return -EINVAL;
>>> -     }
>>
>> Don't you need to check the value of "#address-cells"?
> 
> Doesn't your schema do that?
> 
> It's not the kernel's job to validate the DT. If it is, then it does a
> terrible job.

Ah, this is the code before DT validation, and it's no longer necessary.

>>> -
>>> -     ret = of_property_read_u32(dev->of_node, "#size-cells", &cells);
>>> -     if (ret) {
>>> -             dev_err(dev, "failed to get #size-cells\n");
>>> +     ret = of_range_parser_init(&parser, dev->of_node);
>>> +     if (ret)
>>>                return ret;
>>> -     }
>>> -     if (cells != 1) {
>>> -             dev_err(dev, "#size-cells must be 1\n");
>>> -             return -EINVAL;
>>> -     }
>>
>> Same as "#size-cells"
> 
> While the address clearly needs cells to hold the chip select, there's
> no reason to restrict the size cells.

I see.
I understand that size is limited by value, not by cell width.
It's also no longer necessary.

>>
>> I confirmed the value of all the arguments of
>> uniphier_system_bus_add_bank()
>> match the previous ones.
>>
>> Tested-by: Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>
> 
> Thanks.
Thank you,

---
Best Regards
Kunihiko Hayashi