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Hsu dma optimize #35

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merged 3 commits into from
Dec 16, 2021
Merged

Hsu dma optimize #35

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88e9c1d
8250_mid: arm Rx DMA on all ports with DMA continously
htot Mar 18, 2018
73902db
WIP: serial: 8250_dma: use sgl on transmit
htot May 11, 2021
e12d3f2
serial: 8250_port: when using DMA do not split writes in TTY
htot May 18, 2021
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3 changes: 3 additions & 0 deletions drivers/tty/serial/8250/8250.h
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Original file line number Diff line number Diff line change
Expand Up @@ -49,6 +49,9 @@ struct uart_8250_dma {
unsigned char tx_running;
unsigned char tx_err;
unsigned char rx_running;

unsigned int dma_tx_nents;
struct scatterlist tx_sgl[2];
};

struct old_serial_port {
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29 changes: 24 additions & 5 deletions drivers/tty/serial/8250/8250_dma.c
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Expand Up @@ -62,9 +62,12 @@ static void __dma_rx_complete(void *param)
int serial8250_tx_dma(struct uart_8250_port *p)
{
struct uart_8250_dma *dma = p->dma;
struct scatterlist *sgl = dma->tx_sgl;
struct circ_buf *xmit = &p->port.state->xmit;
struct dma_async_tx_descriptor *desc;
int ret;
size_t chunk1, chunk2;
int head, tail;

if (dma->tx_running)
return 0;
Expand All @@ -75,12 +78,28 @@ int serial8250_tx_dma(struct uart_8250_port *p)
return 0;
}

dma->tx_size = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
head = READ_ONCE(xmit->head);
tail = READ_ONCE(xmit->tail);
dma->dma_tx_nents = 1;
chunk1 = CIRC_CNT_TO_END(head, tail, UART_XMIT_SIZE);
chunk2 = CIRC_CNT(head, tail, UART_XMIT_SIZE) - chunk1;
if (chunk2 == 0) {
sg_init_one(sgl, xmit->buf + tail, chunk1);
} else {
dma->dma_tx_nents++;
sg_init_table(sgl, dma->dma_tx_nents);
sg_set_buf(&sgl[0], xmit->buf + tail, chunk1);
sg_set_buf(&sgl[1], xmit->buf, chunk2);
sg_dma_address(&sgl[1]) = dma->tx_addr;
sg_dma_len(&sgl[1]) = chunk2;
}
sg_dma_address(&sgl[0]) = dma->tx_addr + tail;
sg_dma_len(&sgl[0]) = chunk1;
dma->tx_size = chunk1 + chunk2;

desc = dmaengine_prep_slave_single(dma->txchan,
dma->tx_addr + xmit->tail,
dma->tx_size, DMA_MEM_TO_DEV,
DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
desc = dmaengine_prep_slave_sg(dma->txchan, sgl, dma->dma_tx_nents,
DMA_MEM_TO_DEV,
DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
if (!desc) {
ret = -EBUSY;
goto err;
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27 changes: 27 additions & 0 deletions drivers/tty/serial/8250/8250_mid.c
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Original file line number Diff line number Diff line change
Expand Up @@ -88,6 +88,8 @@ static int tng_handle_irq(struct uart_port *p)
err = hsu_dma_get_status(chip, mid->dma_index * 2 + 1, &status);
if (err > 0) {
serial8250_rx_dma_flush(up);
/* Immediately after flushing arm DMA again */
if (up->dma) up->dma->rx_dma(up);
ret |= 1;
} else if (err == 0)
ret |= hsu_dma_do_irq(chip, mid->dma_index * 2 + 1, status);
Expand Down Expand Up @@ -232,6 +234,29 @@ static void mid8250_set_termios(struct uart_port *p,
serial8250_do_set_termios(p, termios, old);
}

static int mid8250_startup(struct uart_port *port)
{
struct uart_8250_port *up = up_to_u8250p(port);
int ret;

ret = serial8250_do_startup(port);

/* Arm Rx DMA at ->startup() time */

if (up->dma) up->dma->rx_dma(up);

return ret;
}

static void mid8250_shutdown(struct uart_port *port)
{
struct uart_8250_port *up = up_to_u8250p(port);

if (up->dma) serial8250_rx_dma_flush(up);

serial8250_do_shutdown(port);
}

static bool mid8250_dma_filter(struct dma_chan *chan, void *param)
{
struct hsu_dma_slave *s = param;
Expand Down Expand Up @@ -306,6 +331,8 @@ static int mid8250_probe(struct pci_dev *pdev, const struct pci_device_id *id)
uart.port.uartclk = mid->board->base_baud * 16;
uart.port.flags = UPF_SHARE_IRQ | UPF_FIXED_PORT | UPF_FIXED_TYPE;
uart.port.set_termios = mid8250_set_termios;
uart.port.startup = mid8250_startup;
uart.port.shutdown = mid8250_shutdown;

uart.port.mapbase = pci_resource_start(pdev, bar);
uart.port.membase = pcim_iomap(pdev, bar, 0);
Expand Down