linux-kernel - Re: [PATCH 2/2] spi: add driver for STM32 SPI controller

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Date:   Thu, 22 Jun 2017 13:51:56 +0200
From:   Amelie DELAUNAY <amelie.delaunay@...com>
To:     Mark Brown <broonie@...nel.org>
CC:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        <linux-spi@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] spi: add driver for STM32 SPI controller

Hi Mark,

Thanks for your review.

On 06/21/2017 05:13 PM, Mark Brown wrote:
> On Wed, Jun 21, 2017 at 04:32:06PM +0200, Amelie Delaunay wrote:
> 
> A few minor stylistic things but overall this looks really nice, please
> send followup patches fixing these style things.
> 
>> +	/* Determine the first power of 2 greater than or equal to div */
>> +	mbrdiv = (div & (div - 1)) ? fls(div) : fls(div) - 1;
> 
> Please write normal conditional statements, it makes things much easier
> to read.
> OK, I'll fix it in v2.

>> +static bool stm32_spi_can_dma(struct spi_master *master,
>> +			      struct spi_device *spi_dev,
>> +			      struct spi_transfer *transfer)
>> +{
>> +	struct stm32_spi *spi = spi_master_get_devdata(master);
>> +
>> +	dev_dbg(spi->dev, "%s: %s\n", __func__,
>> +		(!!(transfer->len > spi->fifo_size)) ? "true" : "false");
>> +
>> +	return !!(transfer->len > spi->fifo_size);
> 
> This !! is redundant, you're converting a boolean value into a boolean
> value.
> 
You're right.

>> +	buswidth = (spi->cur_bpw <= 8) ? DMA_SLAVE_BUSWIDTH_1_BYTE :
>> +		   (spi->cur_bpw <= 16) ? DMA_SLAVE_BUSWIDTH_2_BYTES :
>> +		   DMA_SLAVE_BUSWIDTH_4_BYTES;
>> +
>> +	/* Valid for DMA Half or Full Fifo threshold */
>> +	maxburst = (spi->cur_fthlv == 2) ? 1 : spi->cur_fthlv;
> 
> Again, please use normal conditional statements - people have to read
> things.
> 
OK.
>> +static int stm32_spi_suspend(struct device *dev)
>> +{
>> +	struct spi_master *master = dev_get_drvdata(dev);
>> +	struct stm32_spi *spi = spi_master_get_devdata(master);
>> +	int ret;
>> +
>> +	ret = spi_master_suspend(master);
>> +	if (ret)
>> +		return ret;
>> +
>> +	clk_disable_unprepare(spi->clk);
> 
> It'd be good to also have the clock disabled by runtime PM, that will
> save a little more power.  There's support for enabling and disabling
> the device in the core so it should just be adding callbacks.  Not
> essential though.
> 
OK I'll have a look.

Regards,
Amelie