On 25/06/2021 09:51, Tamseel Shams wrote: > 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
