linux-kernel - Re: [PATCH] spi: Add FSI-attached SPI controller driver

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Message-ID: <CAHp75Vf3NCkbw39E+d_nf+AyViG2o-u5HxrCjXXmbGk4LaFLog@mail.gmail.com>
Date:   Tue, 4 Feb 2020 13:02:15 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Eddie James <eajames@...ux.vnet.ibm.com>
Cc:     Eddie James <eajames@...ux.ibm.com>,
        linux-spi <linux-spi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Mark Brown <broonie@...nel.org>, Joel Stanley <joel@....id.au>,
        Andrew Jeffery <andrew@...id.au>
Subject: Re: [PATCH] spi: Add FSI-attached SPI controller driver

On Mon, Feb 3, 2020 at 10:33 PM Eddie James <eajames@...ux.vnet.ibm.com> wrote:
> On 1/30/20 10:37 AM, Andy Shevchenko wrote:
> > On Wed, Jan 29, 2020 at 10:09 PM Eddie James <eajames@...ux.ibm.com> wrote:

...

> >> +       struct device *dev;
> > Isn't fsl->dev the same?
> > Perhaps kernel doc to explain the difference?
>
>
> No, it's not the same, as dev here is the SPI controller. I'll add a
> comment.

Why to have duplication then?

> >> +       struct fsi_device *fsi;

...

> >> +       for (i = 0; i < num_bytes; ++i)
> >> +               rx[i] = (u8)((in >> (8 * ((num_bytes - 1) - i))) & 0xffULL);
> > Redundant & 0xffULL part.
> >
> > Isn't it NIH of get_unalinged_be64 / le64 or something similar?
>
>
> No, these are shift in/out operations. The read register will also have
> previous operations data in them and must be extracted with only the
> correct number of bytes.

Why not to call put_unaligned() how the tail in this case (it's 0 or
can be easily made to be 0) will affect the result?

> >> +       return num_bytes;
> >> +}

> >> +static int fsi_spi_data_out(u64 *out, const u8 *tx, int len)
> >> +{
> > Ditto as for above function. (put_unaligned ...)

Ditto.

> >> +}

...

> >> +static int fsi_spi_transfer_data(struct fsi_spi *ctx,
> >> +                                struct spi_transfer *transfer)
> >> +{
> > Can you refactor to tx and rx parts?
>
>
> Why?

It's way too long function to read. Indentation level also can improve
readability.
That's basically what refactoring is for.

> >> +       return 0;
> >> +}

...

> >> +       if ((clock_cfg & (SPI_FSI_CLOCK_CFG_MM_ENABLE |
> >> +                         SPI_FSI_CLOCK_CFG_ECC_DISABLE |
> >> +                         SPI_FSI_CLOCK_CFG_MODE |
> >> +                         SPI_FSI_CLOCK_CFG_SCK_RECV_DEL |
> >> +                         SPI_FSI_CLOCK_CFG_SCK_DIV)) != wanted_clock_cfg)
> >> +               rc = fsi_spi_write_reg(ctx, SPI_FSI_CLOCK_CFG,
> >> +                                      wanted_clock_cfg);
> > Missed {} ?
>
>
> No? It's one line under the if.

One statement, but *two* lines.
What does checkpatch.pl tell you about this?

-- 
With Best Regards,
Andy Shevchenko