linux-kernel - Re: [PATCH v6 1/2] spi: add support for DLN-2 USB-SPI adapter

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Message-ID: <20141127103034.GP2583@lpalcu-linux>
Date:	Thu, 27 Nov 2014 12:30:35 +0200
From:	Laurentiu Palcu <laurentiu.palcu@...el.com>
To:	Mark Brown <broonie@...nel.org>
Cc:	Samuel Ortiz <sameo@...ux.intel.com>,
	Lee Jones <lee.jones@...aro.org>,
	Johan Havold <johan@...nel.org>,
	Octavian Purdila <octavian.purdila@...el.com>,
	linux-spi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 1/2] spi: add support for DLN-2 USB-SPI adapter

On Wed, Nov 26, 2014 at 06:25:21PM +0000, Mark Brown wrote:
> On Wed, Nov 26, 2014 at 12:09:09PM +0200, Laurentiu Palcu wrote:
> 
> > +static int dln2_spi_transfer_one_message(struct spi_master *master,
> > +					 struct spi_message *msg)
> > +{
> > +	struct dln2_spi *dln2 = spi_master_get_devdata(master);
> > +	struct spi_device *spi = msg->spi;
> > +	struct spi_transfer *xfer;
> > +	int status;
> > +
> > +	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
> > +		u8 attr = 0;
> > +
> > +		status = dln2_spi_transfer_setup(dln2, xfer->speed_hz,
> > +						 xfer->bits_per_word,
> > +						 spi->mode);
> > +		if (status < 0) {
> > +			dev_err(&dln2->pdev->dev, "Cannot setup transfer\n");
> > +			break;
> > +		}
> > +
> > +		if (!xfer->cs_change &&
> > +		    !list_is_last(&xfer->transfer_list, &msg->transfers))
> > +			attr = xfer->cs_change ? 0 : DLN2_SPI_ATTR_LEAVE_SS_LOW;
> > +
> > +		status = dln2_spi_rdwr(dln2, xfer->tx_buf, xfer->rx_buf,
> > +				       xfer->len, attr);
> 
> We recently added a spi_transfer_is_last() operation which should allow
> you to move this to using transfer_one() which is a bit nicer.
Ok, sounds good!

> 
> > +	/* enable SPI module, we're good to go */
> > +	ret = dln2_spi_enable(dln2, true);
> > +	if (ret < 0) {
> > +		dev_err(&pdev->dev, "Failed to enable SPI module\n");
> > +		goto exit_free_master;
> > +	}
> 
> It would be nice to have runtime PM operations which keep the device
> disabled when idle, presumably that'd save a bit of power and it's
> generally better practice.
I'll add runtime PM and send a v7.

laurentiu
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