From: Arnd Bergmann <arnd@xxxxxxxx> Since there is no guarantee that the memory returned by dma_alloc_coherent() is associated with a 'struct page', using the architecture specific phys_to_page() is wrong, but using virt_to_page() would be as well. Stop using sg lists altogether and just use the *_single() functions instead. This also simplifies the code a bit since the scatterlists in this driver always have only one entry anyway. gcl: Add a commit log from the initial thread: https://lore.kernel.org/lkml/86db0fe5-930d-4cbb-bd7d-03367da38951@xxxxxxxxxxxxxxxx/ Fixes: cb06ff102e2d7 ("ARM: PL011: Add support for Rx DMA buffer polling.") Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> Tested-by: Gregory CLEMENT <gregory.clement@xxxxxxxxxxx> Signed-off-by: Gregory CLEMENT <gregory.clement@xxxxxxxxxxx> --- drivers/tty/serial/amba-pl011.c | 62 +++++++++++++++------------------ 1 file changed, 29 insertions(+), 33 deletions(-) diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c index 61cc24cd90e4b..73a1c40148c25 100644 --- a/drivers/tty/serial/amba-pl011.c +++ b/drivers/tty/serial/amba-pl011.c @@ -219,8 +219,9 @@ static struct vendor_data vendor_st = { /* Deals with DMA transactions */ struct pl011_sgbuf { - struct scatterlist sg; - char *buf; + dma_addr_t dma; + size_t len; + char *buf; }; struct pl011_dmarx_data { @@ -241,7 +242,8 @@ struct pl011_dmarx_data { struct pl011_dmatx_data { struct dma_chan *chan; - struct scatterlist sg; + dma_addr_t dma; + size_t len; char *buf; bool queued; }; @@ -369,18 +371,11 @@ static int pl011_fifo_to_tty(struct uart_amba_port *uap) static int pl011_sgbuf_init(struct dma_chan *chan, struct pl011_sgbuf *sg, enum dma_data_direction dir) { - dma_addr_t dma_addr; - - sg->buf = dma_alloc_coherent(chan->device->dev, - PL011_DMA_BUFFER_SIZE, &dma_addr, GFP_KERNEL); + sg->buf = dma_alloc_coherent(chan->device->dev, PL011_DMA_BUFFER_SIZE, + &sg->dma, GFP_KERNEL); if (!sg->buf) return -ENOMEM; - - sg_init_table(&sg->sg, 1); - sg_set_page(&sg->sg, phys_to_page(dma_addr), - PL011_DMA_BUFFER_SIZE, offset_in_page(dma_addr)); - sg_dma_address(&sg->sg) = dma_addr; - sg_dma_len(&sg->sg) = PL011_DMA_BUFFER_SIZE; + sg->len = PL011_DMA_BUFFER_SIZE; return 0; } @@ -390,8 +385,7 @@ static void pl011_sgbuf_free(struct dma_chan *chan, struct pl011_sgbuf *sg, { if (sg->buf) { dma_free_coherent(chan->device->dev, - PL011_DMA_BUFFER_SIZE, sg->buf, - sg_dma_address(&sg->sg)); + PL011_DMA_BUFFER_SIZE, sg->buf, sg->dma); } } @@ -552,8 +546,8 @@ static void pl011_dma_tx_callback(void *data) uart_port_lock_irqsave(&uap->port, &flags); if (uap->dmatx.queued) - dma_unmap_sg(dmatx->chan->device->dev, &dmatx->sg, 1, - DMA_TO_DEVICE); + dma_unmap_single(dmatx->chan->device->dev, dmatx->dma, + dmatx->len, DMA_TO_DEVICE); dmacr = uap->dmacr; uap->dmacr = dmacr & ~UART011_TXDMAE; @@ -639,18 +633,19 @@ static int pl011_dma_tx_refill(struct uart_amba_port *uap) memcpy(&dmatx->buf[first], &xmit->buf[0], second); } - dmatx->sg.length = count; - - if (dma_map_sg(dma_dev->dev, &dmatx->sg, 1, DMA_TO_DEVICE) != 1) { + dmatx->len = count; + dmatx->dma = dma_map_single(dma_dev->dev, dmatx->buf, count, + DMA_TO_DEVICE); + if (dmatx->dma == DMA_MAPPING_ERROR) { uap->dmatx.queued = false; dev_dbg(uap->port.dev, "unable to map TX DMA\n"); return -EBUSY; } - desc = dmaengine_prep_slave_sg(chan, &dmatx->sg, 1, DMA_MEM_TO_DEV, + desc = dmaengine_prep_slave_single(chan, dmatx->dma, dmatx->len, DMA_MEM_TO_DEV, DMA_PREP_INTERRUPT | DMA_CTRL_ACK); if (!desc) { - dma_unmap_sg(dma_dev->dev, &dmatx->sg, 1, DMA_TO_DEVICE); + dma_unmap_single(dma_dev->dev, dmatx->dma, dmatx->len, DMA_TO_DEVICE); uap->dmatx.queued = false; /* * If DMA cannot be used right now, we complete this @@ -813,8 +808,8 @@ __acquires(&uap->port.lock) dmaengine_terminate_async(uap->dmatx.chan); if (uap->dmatx.queued) { - dma_unmap_sg(uap->dmatx.chan->device->dev, &uap->dmatx.sg, 1, - DMA_TO_DEVICE); + dma_unmap_single(uap->dmatx.chan->device->dev, uap->dmatx.dma, + uap->dmatx.len, DMA_TO_DEVICE); uap->dmatx.queued = false; uap->dmacr &= ~UART011_TXDMAE; pl011_write(uap->dmacr, uap, REG_DMACR); @@ -836,7 +831,7 @@ static int pl011_dma_rx_trigger_dma(struct uart_amba_port *uap) /* Start the RX DMA job */ sgbuf = uap->dmarx.use_buf_b ? &uap->dmarx.sgbuf_b : &uap->dmarx.sgbuf_a; - desc = dmaengine_prep_slave_sg(rxchan, &sgbuf->sg, 1, + desc = dmaengine_prep_slave_single(rxchan, sgbuf->dma, sgbuf->len, DMA_DEV_TO_MEM, DMA_PREP_INTERRUPT | DMA_CTRL_ACK); /* @@ -886,7 +881,7 @@ static void pl011_dma_rx_chars(struct uart_amba_port *uap, if (uap->dmarx.poll_rate) { /* The data can be taken by polling */ - dmataken = sgbuf->sg.length - dmarx->last_residue; + dmataken = sgbuf->len - dmarx->last_residue; /* Recalculate the pending size */ if (pending >= dmataken) pending -= dmataken; @@ -911,7 +906,7 @@ static void pl011_dma_rx_chars(struct uart_amba_port *uap, /* Reset the last_residue for Rx DMA poll */ if (uap->dmarx.poll_rate) - dmarx->last_residue = sgbuf->sg.length; + dmarx->last_residue = sgbuf->len; /* * Only continue with trying to read the FIFO if all DMA chars have @@ -969,7 +964,7 @@ static void pl011_dma_rx_irq(struct uart_amba_port *uap) pl011_write(uap->dmacr, uap, REG_DMACR); uap->dmarx.running = false; - pending = sgbuf->sg.length - state.residue; + pending = sgbuf->len - state.residue; BUG_ON(pending > PL011_DMA_BUFFER_SIZE); /* Then we terminate the transfer - we now know our residue */ dmaengine_terminate_all(rxchan); @@ -1015,7 +1010,7 @@ static void pl011_dma_rx_callback(void *data) * the DMA irq handler. So we check the residue here. */ rxchan->device->device_tx_status(rxchan, dmarx->cookie, &state); - pending = sgbuf->sg.length - state.residue; + pending = sgbuf->len - state.residue; BUG_ON(pending > PL011_DMA_BUFFER_SIZE); /* Then we terminate the transfer - we now know our residue */ dmaengine_terminate_all(rxchan); @@ -1074,7 +1069,7 @@ static void pl011_dma_rx_poll(struct timer_list *t) sgbuf = dmarx->use_buf_b ? &uap->dmarx.sgbuf_b : &uap->dmarx.sgbuf_a; rxchan->device->device_tx_status(rxchan, dmarx->cookie, &state); if (likely(state.residue < dmarx->last_residue)) { - dmataken = sgbuf->sg.length - dmarx->last_residue; + dmataken = sgbuf->len - dmarx->last_residue; size = dmarx->last_residue - state.residue; dma_count = tty_insert_flip_string(port, sgbuf->buf + dmataken, size); @@ -1123,7 +1118,7 @@ static void pl011_dma_startup(struct uart_amba_port *uap) return; } - sg_init_one(&uap->dmatx.sg, uap->dmatx.buf, PL011_DMA_BUFFER_SIZE); + uap->dmatx.len = PL011_DMA_BUFFER_SIZE; /* The DMA buffer is now the FIFO the TTY subsystem can use */ uap->port.fifosize = PL011_DMA_BUFFER_SIZE; @@ -1200,8 +1195,9 @@ static void pl011_dma_shutdown(struct uart_amba_port *uap) /* In theory, this should already be done by pl011_dma_flush_buffer */ dmaengine_terminate_all(uap->dmatx.chan); if (uap->dmatx.queued) { - dma_unmap_sg(uap->dmatx.chan->device->dev, &uap->dmatx.sg, 1, - DMA_TO_DEVICE); + dma_unmap_single(uap->dmatx.chan->device->dev, + uap->dmatx.dma, uap->dmatx.len, + DMA_TO_DEVICE); uap->dmatx.queued = false; } -- 2.42.0
