forked from Minki/linux
spi: rspi: Handle dmaengine_prep_slave_sg() failures gracefully
As typically a shmobile SoC has less DMA channels than devices that can use DMA, we may want to prioritize access to the DMA channels in the future. This means that dmaengine_prep_slave_sg() may start failing arbitrarily. Handle dmaengine_prep_slave_sg() failures gracefully by falling back to PIO. Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Mark Brown <broonie@linaro.org>
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533465a8f8
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85912a88c1
@ -477,7 +477,7 @@ static int rspi_dma_transfer(struct rspi_data *rspi, struct sg_table *tx,
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tx->sgl, tx->nents, DMA_TO_DEVICE,
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DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
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if (!desc_tx)
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return -EIO;
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goto no_dma;
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irq_mask |= SPCR_SPTIE;
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}
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@ -486,7 +486,7 @@ static int rspi_dma_transfer(struct rspi_data *rspi, struct sg_table *tx,
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rx->sgl, rx->nents, DMA_FROM_DEVICE,
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DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
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if (!desc_rx)
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return -EIO;
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goto no_dma;
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irq_mask |= SPCR_SPRIE;
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}
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@ -540,6 +540,12 @@ static int rspi_dma_transfer(struct rspi_data *rspi, struct sg_table *tx,
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enable_irq(rspi->rx_irq);
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return ret;
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no_dma:
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pr_warn_once("%s %s: DMA not available, falling back to PIO\n",
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dev_driver_string(&rspi->master->dev),
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dev_name(&rspi->master->dev));
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return -EAGAIN;
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}
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static void rspi_receive_init(const struct rspi_data *rspi)
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@ -593,8 +599,10 @@ static int rspi_common_transfer(struct rspi_data *rspi,
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if (rspi->master->can_dma && __rspi_can_dma(rspi, xfer)) {
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/* rx_buf can be NULL on RSPI on SH in TX-only Mode */
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return rspi_dma_transfer(rspi, &xfer->tx_sg,
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xfer->rx_buf ? &xfer->rx_sg : NULL);
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ret = rspi_dma_transfer(rspi, &xfer->tx_sg,
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xfer->rx_buf ? &xfer->rx_sg : NULL);
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if (ret != -EAGAIN)
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return ret;
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}
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ret = rspi_pio_transfer(rspi, xfer->tx_buf, xfer->rx_buf, xfer->len);
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@ -648,8 +656,11 @@ static int qspi_transfer_out(struct rspi_data *rspi, struct spi_transfer *xfer)
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{
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int ret;
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if (rspi->master->can_dma && __rspi_can_dma(rspi, xfer))
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return rspi_dma_transfer(rspi, &xfer->tx_sg, NULL);
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if (rspi->master->can_dma && __rspi_can_dma(rspi, xfer)) {
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ret = rspi_dma_transfer(rspi, &xfer->tx_sg, NULL);
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if (ret != -EAGAIN)
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return ret;
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}
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ret = rspi_pio_transfer(rspi, xfer->tx_buf, NULL, xfer->len);
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if (ret < 0)
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@ -663,8 +674,11 @@ static int qspi_transfer_out(struct rspi_data *rspi, struct spi_transfer *xfer)
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static int qspi_transfer_in(struct rspi_data *rspi, struct spi_transfer *xfer)
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{
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if (rspi->master->can_dma && __rspi_can_dma(rspi, xfer))
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return rspi_dma_transfer(rspi, NULL, &xfer->rx_sg);
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if (rspi->master->can_dma && __rspi_can_dma(rspi, xfer)) {
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int ret = rspi_dma_transfer(rspi, NULL, &xfer->rx_sg);
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if (ret != -EAGAIN)
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return ret;
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}
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return rspi_pio_transfer(rspi, NULL, xfer->rx_buf, xfer->len);
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}
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