linux-kernel - Re: [PATCH 03/11] spi: Add a driver for the Freescale/NXP QuadSPI controller

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Message-ID: <CAHp75VfskABz+KrnLzDTYH=1cESimi++3HwQ2a1tiWkPTqf=HQ@mail.gmail.com>
Date:   Tue, 26 Jun 2018 16:18:44 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Frieder Schrempf <frieder.schrempf@...eet.de>
Cc:     "linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
        Yogesh Narayan Gaur <yogeshnarayan.gaur@....com>,
        "boris.brezillon@...tlin.com" <boris.brezillon@...tlin.com>,
        "linux-spi@...r.kernel.org" <linux-spi@...r.kernel.org>,
        "dwmw2@...radead.org" <dwmw2@...radead.org>,
        "computersforpeace@...il.com" <computersforpeace@...il.com>,
        "marek.vasut@...il.com" <marek.vasut@...il.com>,
        "richard@....at" <richard@....at>,
        "miquel.raynal@...tlin.com" <miquel.raynal@...tlin.com>,
        "broonie@...nel.org" <broonie@...nel.org>,
        David Wolfe <david.wolfe@....com>,
        Fabio Estevam <fabio.estevam@....com>,
        Prabhakar Kushwaha <prabhakar.kushwaha@....com>,
        Han Xu <han.xu@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 03/11] spi: Add a driver for the Freescale/NXP QuadSPI controller

On Tue, Jun 26, 2018 at 3:26 PM, Frieder Schrempf
<frieder.schrempf@...eet.de> wrote:
> On 08.06.2018 22:27, Andy Shevchenko wrote:
>> On Fri, Jun 8, 2018 at 2:54 PM, Yogesh Narayan Gaur
>> <yogeshnarayan.gaur@....com> wrote:

>>> +static int fsl_qspi_check_buswidth(struct fsl_qspi *q, u8 width) {

>>> +       switch (width) {
>>> +       case 1:
>>> +       case 2:
>>> +       case 4:
>>> +               return 0;
>>> +       }

>> if (!is_power_of_2(width) || width >= 8)
>>   return -E...;
>>
>> return 0;
>>
>> ?

> Your proposition is a bit shorter, but I think it's slightly harder to read.

OK.

>>> +
>>> +       return -ENOTSUPP;
>>> +}


>>> +       for (i = 0; i < op->data.nbytes; i += 4) {
>>> +               u32 val = 0;
>>> +
>>> +               memcpy(&val, op->data.buf.out + i,

>>> +                      min_t(unsigned int, op->data.nbytes - i, 4));

>> You may easily avoid this conditional on each iteration.

> Do you mean something like this, or are there better ways?
>
> u32 val = 0;
>
> for (i = 0; i < ALIGN_DOWN(op->data.nbytes, 4); i += 4)
> {
>         memcpy(&val, op->data.buf.out + i, 4);
>         val = fsl_qspi_endian_xchg(q, val);
>         qspi_writel(q, val, base + QUADSPI_TBDR);
> }
>
> memcpy(&val, op->data.buf.out + i, op->data.nbytes);
> val = fsl_qspi_endian_xchg(q, val);
> qspi_writel(q, val, base + QUADSPI_TBDR);

Something like this, though last part should go under

if (IS_ALIGNED(...))

(My comment was about moving out an invariant conditional)

>>> +               val = fsl_qspi_endian_xchg(q, val);
>>> +               qspi_writel(q, val, base + QUADSPI_TBDR);
>>> +       }

>>> +MODULE_AUTHOR("Freescale Semiconductor Inc."); MODULE_AUTHOR("Boris
>>> +Brezillion <boris.brezillon@...tlin.com>"); MODULE_AUTHOR("Frieder
>>> +Schrempf <frieder.schrempf@...eet.de>"); MODULE_LICENSE("GPL v2");

>> Wrong indentation.

> What is wrong? Some newlines are missing here between the MODULE_ macros,
> but in my original patch it seems correct.

It should be like

MODULE_FOO(...);
MODULE_BAR(...);
MODULE_BAZ(...);

One macro — one line.

-- 
With Best Regards,
Andy Shevchenko