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Date:   Fri, 11 Feb 2022 11:57:15 +0000
From:   Mark Brown <broonie@kernel.org>
To:     Lh Kuo =?utf-8?B?6YOt5Yqb6LGq?= <lh.Kuo@sunplus.com>
Cc:     Tom Rix <trix@redhat.com>, Li-hao Kuo <lhjeff911@gmail.com>,
        "linux-spi@vger.kernel.org" <linux-spi@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Wells Lu =?utf-8?B?5ZGC6Iqz6aiw?= <wells.lu@sunplus.com>
Subject: Re: [PATCH] spi: Fix warning for Clang build
Message-ID: <YgZPGyMjJ10eK/SG@sirena.org.uk>
References: <691d52b72f978f562136c587319852f5c65f08fe.1644460444.git.lhjeff911@gmail.com>
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On Fri, Feb 11, 2022 at 04:59:00AM +0000, Lh Kuo =E9=83=AD=E5=8A=9B=E8=B1=
=AA wrote:
> Yes. I think the function can be simplified as follows

> static int sp7021_spi_slave_transfer_one(struct spi_controller *ctlr, str=
uct spi_device *spi,
> 				       struct spi_transfer *xfer)
> {
> 	struct sp7021_spi_ctlr *pspim =3D spi_master_get_devdata(ctlr);
> 	struct device *dev =3D pspim->dev;
> 	int ret;
>=20
> 	mode =3D SP7021_SPI_IDLE;
> 	if (xfer->tx_buf && xfer->rx_buf) {
> 		dev_dbg(&ctlr->dev, "%s() wrong command\n", __func__);
> 		return -EINVAL;

Since only unidirectional transfers are supported...

> 	} else if (xfer->tx_buf) {
> 		xfer->tx_dma =3D dma_map_single(dev, (void *)xfer->tx_buf,
> 					      xfer->len, DMA_TO_DEVICE);
> 		if (dma_mapping_error(dev, xfer->tx_dma))
> 			return -ENOMEM;
> 		ret =3D sp7021_spi_slave_tx(spi, xfer);
> 	} else if (xfer->rx_buf) {
> 		xfer->rx_dma =3D dma_map_single(dev, xfer->rx_buf, xfer->len,
> 					      DMA_FROM_DEVICE);
> 		if (dma_mapping_error(dev, xfer->rx_dma))
> 			return -ENOMEM;
> 		ret =3D sp7021_spi_slave_rx(spi, xfer);
> 	}
>=20
> 	if (xfer->tx_buf)
> 		dma_unmap_single(dev, xfer->tx_dma, xfer->len, DMA_TO_DEVICE);
> 	if (xfer->rx_buf)
> 		dma_unmap_single(dev, xfer->rx_dma, xfer->len, DMA_FROM_DEVICE);

=2E..you could even fold the unmapping into the if/else tree above.
Otherwise this looks good to me, please send a patch.

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