> > When DMA is used for TX and RX by serial driver, it should pass the > > DMA device pointer to DMA API instead of UART device pointer. DMA > > device should be used for DMA API because only the DMA device is aware > > of how the device connects to the memory. > > There might be an extra level of address translation due to a SMMU > > attached to the DMA device. When serial device is used for DMA API, > > the DMA API will have no clue of the SMMU attached to the DMA device. > > > > This patch is necessary to fix the SMMU page faults which is observed > > when a DMA(with SMMU enabled) is attached to UART for transfer. > > > > Signed-off-by: Tamseel Shams <m.shams@xxxxxxxxxxx> > > Signed-off-by: Ajay Kumar <ajaykumar.rs@xxxxxxxxxxx> > > --- > > Changes since v1: > > 1. Rebased the patch on "tty-next" branch of TTY driver tree > > > > Changes since v2: > > 1. Updated the commit message. > > 2. Changed the comment description > > > > Changes since v3: > > 1. Removed the null pointer check for "dma", "dma->tx_chan" and > > "dma->rx_chan" and instead sending DMA device pointer while calling > > DMA API. > > > > drivers/tty/serial/samsung_tty.c | 32 > > ++++++++++++++++---------------- > > 1 file changed, 16 insertions(+), 16 deletions(-) > > > > diff --git a/drivers/tty/serial/samsung_tty.c > > b/drivers/tty/serial/samsung_tty.c > > index 9fbc61151c2e..fa30aa20a13f 100644 > > --- a/drivers/tty/serial/samsung_tty.c > > +++ b/drivers/tty/serial/samsung_tty.c > > @@ -305,7 +305,7 @@ static void s3c24xx_serial_stop_tx(struct uart_port > *port) > > dmaengine_pause(dma->tx_chan); > > dmaengine_tx_status(dma->tx_chan, dma->tx_cookie, &state); > > dmaengine_terminate_all(dma->tx_chan); > > - dma_sync_single_for_cpu(ourport->port.dev, > > + dma_sync_single_for_cpu(dma->tx_chan->device->dev, > > dma->tx_transfer_addr, dma->tx_size, > DMA_TO_DEVICE); > > async_tx_ack(dma->tx_desc); > > count = dma->tx_bytes_requested - state.residue; @@ -338,8 > +338,8 > > @@ static void s3c24xx_serial_tx_dma_complete(void *args) > > count = dma->tx_bytes_requested - state.residue; > > async_tx_ack(dma->tx_desc); > > > > - dma_sync_single_for_cpu(ourport->port.dev, dma->tx_transfer_addr, > > - dma->tx_size, DMA_TO_DEVICE); > > + dma_sync_single_for_cpu(dma->tx_chan->device->dev, > > + dma->tx_transfer_addr, dma->tx_size, > DMA_TO_DEVICE); > > Looks like alignment is broken here. However even if the line was not aligned > before, please fix it up now - align the arguments like checkpatch suggests. > > This applies to other places as well. Thanks. > > Best regards, > Krzysztof Hi Krzysztof, Will fix the alignments in the next version. Thanks & Regards, Tamseel Shams
