linux-kernel - Re: [PATCH v7 2/2] mtd: rawnand: Add NAND controller support on Intel LGM SoC

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Message-ID: <5180e734-ff56-db5a-ab49-8a55cfa2f2c0@linux.intel.com>
Date:   Mon, 18 May 2020 19:39:22 +0800
From:   "Ramuthevar, Vadivel MuruganX" 
        <vadivel.muruganx.ramuthevar@...ux.intel.com>
To:     Arnd Bergmann <arnd@...db.de>,
        Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     kbuild test robot <lkp@...el.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "open list:MEMORY TECHNOLOGY..." <linux-mtd@...ts.infradead.org>,
        devicetree <devicetree@...r.kernel.org>, kbuild-all@...ts.01.org,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh R <vigneshr@...com>,
        Brendan Higgins <brendanhiggins@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Boris Brezillon <boris.brezillon@...labora.com>,
        Anders Roxell <anders.roxell@...aro.org>,
        masonccyang@...c.com.tw
Subject: Re: [PATCH v7 2/2] mtd: rawnand: Add NAND controller support on Intel
 LGM SoC

Hi Arnd, Andy,

On 15/5/2020 10:30 pm, Arnd Bergmann wrote:
> On Fri, May 15, 2020 at 4:25 PM Andy Shevchenko
> <andy.shevchenko@...il.com> wrote:
>>
>> On Fri, May 15, 2020 at 4:48 PM kbuild test robot <lkp@...el.com> wrote:
>>
>>> sparse warnings: (new ones prefixed by >>)
>>>
>>>>> drivers/mtd/nand/raw/intel-nand-controller.c:441:24: sparse: sparse: incorrect type in argument 1 (different base types) @@    expected unsigned int val @@    got restricted __be32 [assignedunsigned int val @@
>>>>> drivers/mtd/nand/raw/intel-nand-controller.c:441:24: sparse:    expected unsigned int val
>>>>> drivers/mtd/nand/raw/intel-nand-controller.c:441:24: sparse:    got restricted __be32 [assigned] [usertype] reg
>>>     drivers/mtd/nand/raw/intel-nand-controller.c:444:24: sparse: sparse: incorrect type in argument 1 (different base types) @@    expected unsigned int val @@    got restricted __be32 [assignedunsigned int val @@
>>>     drivers/mtd/nand/raw/intel-nand-controller.c:444:24: sparse:    expected unsigned int val
>>>     drivers/mtd/nand/raw/intel-nand-controller.c:444:24: sparse:    got restricted __be32 [assigned] [usertype] reg
>>>
>>>     440                  reg = cpu_to_be32(*pdata++);
>>>   > 441                  writel(reg, ebu_host->hsnand + HSNAND_CMSG_0);
>>>     442
>>>     443                  reg = cpu_to_be32(*pdata);
>>>     444                  writel(reg, ebu_host->hsnand + HSNAND_CMSG_1);
>>
>> On BE:
>> cpu_to_be32 -> no-op
>> writel() -> converts reg to LE
>>
>> On LE:
>> cpu_to_be32 -> converts to BE
>> writel() -> no-op (in terms of conversion)
>>
>> Seems to me that the proper API (if above is intended) should be swab32().
>> But something tells me that above is broken (or my understanding is wrong).
> 
> iowrite_be32() is the correct way to store word into a big-endian mmio register,
> if that is the intention here.
Thank you for suggestions to use iowrite32be(), it suits exactly.

Regards
Vadivel

> 
>        Arnd
>