Re: [PATCH] spi: Fix warning for Clang build

[Mark Brown <broonie@kernel.org>]

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On Fri, Feb 11, 2022 at 04:59:00AM +0000, Lh Kuo 郭力豪 wrote:
> Yes. I think the function can be simplified as follows

> static int sp7021_spi_slave_transfer_one(struct spi_controller *ctlr, struct spi_device *spi,
> 				       struct spi_transfer *xfer)
> {
> 	struct sp7021_spi_ctlr *pspim = spi_master_get_devdata(ctlr);
> 	struct device *dev = pspim->dev;
> 	int ret;
> 
> 	mode = 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 = dma_map_single(dev, (void *)xfer->tx_buf,
> 					      xfer->len, DMA_TO_DEVICE);
> 		if (dma_mapping_error(dev, xfer->tx_dma))
> 			return -ENOMEM;
> 		ret = sp7021_spi_slave_tx(spi, xfer);
> 	} else if (xfer->rx_buf) {
> 		xfer->rx_dma = dma_map_single(dev, xfer->rx_buf, xfer->len,
> 					      DMA_FROM_DEVICE);
> 		if (dma_mapping_error(dev, xfer->rx_dma))
> 			return -ENOMEM;
> 		ret = sp7021_spi_slave_rx(spi, xfer);
> 	}
> 
> 	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);

...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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