linux-kernel - Re: [PATCH 11/30] spi: dw: Add DWC SSI capability

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Date:   Wed, 30 Sep 2020 01:17:37 +0300
From:   Serge Semin <Sergey.Semin@...kalelectronics.ru>
To:     Mark Brown <broonie@...nel.org>
CC:     Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
        Ramil Zaripov <Ramil.Zaripov@...kalelectronics.ru>,
        Pavel Parkhomenko <Pavel.Parkhomenko@...kalelectronics.ru>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Lars Povlsen <lars.povlsen@...rochip.com>,
        "wuxu . wu" <wuxu.wu@...wei.com>, Feng Tang <feng.tang@...el.com>,
        Rob Herring <robh+dt@...nel.org>, <linux-spi@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 11/30] spi: dw: Add DWC SSI capability

On Tue, Sep 29, 2020 at 02:52:33PM +0100, Mark Brown wrote:
> On Sun, Sep 20, 2020 at 02:28:55PM +0300, Serge Semin wrote:
> 
> > -	/*
> > -	 * SPI mode (SCPOL|SCPH)
> > -	 * CTRLR0[ 8] Serial Clock Phase
> > -	 * CTRLR0[ 9] Serial Clock Polarity
> > -	 */
> > -	cr0 |= ((spi->mode & SPI_CPOL) ? 1 : 0) << DWC_SSI_CTRLR0_SCPOL_OFFSET;
> > -	cr0 |= ((spi->mode & SPI_CPHA) ? 1 : 0) << DWC_SSI_CTRLR0_SCPH_OFFSET;
> 

> > +		cr0 |= SSI_MOTO_SPI << DWC_SSI_CTRLR0_FRF_OFFSET;
> > +		cr0 |= ((spi->mode & SPI_CPOL) ? 1 : 0) << DWC_SSI_CTRLR0_SCPOL_OFFSET;
> > +		cr0 |= ((spi->mode & SPI_CPHA) ? 1 : 0) << DWC_SSI_CTRLR0_SCPH_OFFSET;
> 
> The new code seems less well commented than the old code here.

You are right. The comments are omitted. The thing is that they are absolutely
redundant here, for the same reason they haven't been added to the standard
update_cr0() method. Both the DWC SSI-capable and standard DW APB SSI-specific
part of the code do the same thing: setup the CTRLR0 fields, which are described
by the macro definitions. So there is no need to duplicate that information in
the comments, moreover seeing it can be inferred from the code.

-Sergey