From 88b0aa544af58ce3be125a1845a227264ec9ab89 Mon Sep 17 00:00:00 2001 From: Daniel Kurtz Date: Fri, 27 Jan 2017 00:21:53 +0800 Subject: [PATCH] spi: When no dma_chan map buffers with spi_master's parent Back before commit 1dccb598df54 ("arm64: simplify dma_get_ops"), for arm64, devices for which dma_ops were not explicitly set were automatically configured to use swiotlb_dma_ops, since this was hard-coded as the global "dma_ops" in arm64_dma_init(). Now that global "dma_ops" has been removed, all devices much have their dma_ops explicitly set by a call to arch_setup_dma_ops(), otherwise the device is assigned dummy_dma_ops, and thus calls to map_sg for such a device will fail (return 0). Mediatek SPI uses DMA but does not use a dma channel. Support for this was added by commit c37f45b5f1cd ("spi: support spi without dma channel to use can_dma()"), which uses the master_spi dev to DMA map buffers. The master_spi device is not a platform device, rather it is created in spi_alloc_device(), and therefore its dma_ops are never set. Therefore, when the mediatek SPI driver when it does DMA (for large SPI transactions > 32 bytes), SPI will use spi_map_buf()->dma_map_sg() to map the buffer for use in DMA. But dma_map_sg()->dma_map_sg_attrs() returns 0, because ops->map_sg is dummy_dma_ops->__dummy_map_sg, and hence spi_map_buf() returns -ENOMEM (-12). Fix this by using the real spi_master's parent device which should be a real physical device with DMA properties. Signed-off-by: Daniel Kurtz Fixes: c37f45b5f1cd ("spi: support spi without dma channel to use can_dma()") Cc: Leilk Liu Signed-off-by: Mark Brown --- drivers/spi/spi.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 656dd3e3220c..f4d412e48e1c 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -805,12 +805,12 @@ static int __spi_map_msg(struct spi_master *master, struct spi_message *msg) if (master->dma_tx) tx_dev = master->dma_tx->device->dev; else - tx_dev = &master->dev; + tx_dev = master->dev.parent; if (master->dma_rx) rx_dev = master->dma_rx->device->dev; else - rx_dev = &master->dev; + rx_dev = master->dev.parent; list_for_each_entry(xfer, &msg->transfers, transfer_list) { if (!master->can_dma(master, msg->spi, xfer)) @@ -852,12 +852,12 @@ static int __spi_unmap_msg(struct spi_master *master, struct spi_message *msg) if (master->dma_tx) tx_dev = master->dma_tx->device->dev; else - tx_dev = &master->dev; + tx_dev = master->dev.parent; if (master->dma_rx) rx_dev = master->dma_rx->device->dev; else - rx_dev = &master->dev; + rx_dev = master->dev.parent; list_for_each_entry(xfer, &msg->transfers, transfer_list) { if (!master->can_dma(master, msg->spi, xfer))