Re: [PATCH] serial: msm: Unify TX and RX DMA paths
From: neil . armstrong
Date: Tue Apr 23 2024 - 10:08:23 EST
Hi Marek,
On 23/04/2024 14:08, Marek Szyprowski wrote:
Use scatterlist-based API also for RX mode to unify TX and RX DMA paths
as well as simplify the whole driver code a bit.
Thanks for the patch, I have no idea if this is right or wrong.
Greg, I think we should wait until this change is fully tested on multiple
platforms including DMA usage (bluetooth) before aplying it.
Thanks,
Neil
Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
---
drivers/tty/serial/msm_serial.c | 86 +++++++++++++--------------------
1 file changed, 34 insertions(+), 52 deletions(-)
diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c
index 0a9c5219df88..d5e00e613f73 100644
--- a/drivers/tty/serial/msm_serial.c
+++ b/drivers/tty/serial/msm_serial.c
@@ -161,14 +161,8 @@ enum {
struct msm_dma {
struct dma_chan *chan;
enum dma_data_direction dir;
- union {
- struct {
- dma_addr_t phys;
- unsigned char *virt;
- unsigned int count;
- } rx;
- struct scatterlist tx_sg;
- };
+ unsigned char *virt;
+ struct scatterlist sg;
dma_cookie_t cookie;
u32 enable_bit;
struct dma_async_tx_descriptor *desc;
@@ -254,13 +248,7 @@ static void msm_stop_dma(struct uart_port *port, struct msm_dma *dma)
unsigned int mapped;
u32 val;
- if (dma->dir == DMA_TO_DEVICE) {
- mapped = sg_dma_len(&dma->tx_sg);
- } else {
- mapped = dma->rx.count;
- dma->rx.count = 0;
- }
-
+ mapped = sg_dma_len(&dma->sg);
dmaengine_terminate_all(dma->chan);
/*
@@ -275,11 +263,8 @@ static void msm_stop_dma(struct uart_port *port, struct msm_dma *dma)
msm_write(port, val, UARTDM_DMEN);
if (mapped) {
- if (dma->dir == DMA_TO_DEVICE) {
- dma_unmap_sg(dev, &dma->tx_sg, 1, dma->dir);
- sg_init_table(&dma->tx_sg, 1);
- } else
- dma_unmap_single(dev, dma->rx.phys, mapped, dma->dir);
+ dma_unmap_sg(dev, &dma->sg, 1, dma->dir);
+ sg_init_table(&dma->sg, 1);
}
}
@@ -299,7 +284,7 @@ static void msm_release_dma(struct msm_port *msm_port)
if (dma->chan) {
msm_stop_dma(&msm_port->uart, dma);
dma_release_channel(dma->chan);
- kfree(dma->rx.virt);
+ kfree(dma->virt);
}
memset(dma, 0, sizeof(*dma));
@@ -371,8 +356,8 @@ static void msm_request_rx_dma(struct msm_port *msm_port, resource_size_t base)
of_property_read_u32(dev->of_node, "qcom,rx-crci", &crci);
- dma->rx.virt = kzalloc(UARTDM_RX_SIZE, GFP_KERNEL);
- if (!dma->rx.virt)
+ dma->virt = kzalloc(UARTDM_RX_SIZE, GFP_KERNEL);
+ if (!dma->virt)
goto rel_rx;
memset(&conf, 0, sizeof(conf));
@@ -399,7 +384,7 @@ static void msm_request_rx_dma(struct msm_port *msm_port, resource_size_t base)
return;
err:
- kfree(dma->rx.virt);
+ kfree(dma->virt);
rel_rx:
dma_release_channel(dma->chan);
no_rx:
@@ -434,7 +419,7 @@ static void msm_start_tx(struct uart_port *port)
struct msm_dma *dma = &msm_port->tx_dma;
/* Already started in DMA mode */
- if (sg_dma_len(&dma->tx_sg))
+ if (sg_dma_len(&dma->sg))
return;
msm_port->imr |= MSM_UART_IMR_TXLEV;
@@ -462,12 +447,12 @@ static void msm_complete_tx_dma(void *args)
uart_port_lock_irqsave(port, &flags);
/* Already stopped */
- if (!sg_dma_len(&dma->tx_sg))
+ if (!sg_dma_len(&dma->sg))
goto done;
dmaengine_tx_status(dma->chan, dma->cookie, &state);
- dma_unmap_sg(port->dev, &dma->tx_sg, 1, dma->dir);
+ dma_unmap_sg(port->dev, &dma->sg, 1, dma->dir);
val = msm_read(port, UARTDM_DMEN);
val &= ~dma->enable_bit;
@@ -478,9 +463,9 @@ static void msm_complete_tx_dma(void *args)
msm_write(port, MSM_UART_CR_TX_ENABLE, MSM_UART_CR);
}
- count = sg_dma_len(&dma->tx_sg) - state.residue;
+ count = sg_dma_len(&dma->sg) - state.residue;
uart_xmit_advance(port, count);
- sg_init_table(&dma->tx_sg, 1);
+ sg_init_table(&dma->sg, 1);
/* Restore "Tx FIFO below watermark" interrupt */
msm_port->imr |= MSM_UART_IMR_TXLEV;
@@ -503,16 +488,16 @@ static int msm_handle_tx_dma(struct msm_port *msm_port, unsigned int count)
int ret;
u32 val;
- sg_init_table(&dma->tx_sg, 1);
- kfifo_dma_out_prepare(&tport->xmit_fifo, &dma->tx_sg, 1, count);
+ sg_init_table(&dma->sg, 1);
+ kfifo_dma_out_prepare(&tport->xmit_fifo, &dma->sg, 1, count);
- mapped = dma_map_sg(port->dev, &dma->tx_sg, 1, dma->dir);
+ mapped = dma_map_sg(port->dev, &dma->sg, 1, dma->dir);
if (!mapped) {
ret = -EIO;
goto zero_sg;
}
- dma->desc = dmaengine_prep_slave_sg(dma->chan, &dma->tx_sg, 1,
+ dma->desc = dmaengine_prep_slave_sg(dma->chan, &dma->sg, 1,
DMA_MEM_TO_DEV,
DMA_PREP_INTERRUPT |
DMA_PREP_FENCE);
@@ -550,9 +535,9 @@ static int msm_handle_tx_dma(struct msm_port *msm_port, unsigned int count)
dma_async_issue_pending(dma->chan);
return 0;
unmap:
- dma_unmap_sg(port->dev, &dma->tx_sg, 1, dma->dir);
+ dma_unmap_sg(port->dev, &dma->sg, 1, dma->dir);
zero_sg:
- sg_init_table(&dma->tx_sg, 1);
+ sg_init_table(&dma->sg, 1);
return ret;
}
@@ -569,7 +554,7 @@ static void msm_complete_rx_dma(void *args)
uart_port_lock_irqsave(port, &flags);
/* Already stopped */
- if (!dma->rx.count)
+ if (!sg_dma_len(&dma->sg))
goto done;
val = msm_read(port, UARTDM_DMEN);
@@ -586,14 +571,13 @@ static void msm_complete_rx_dma(void *args)
port->icount.rx += count;
- dma->rx.count = 0;
-
- dma_unmap_single(port->dev, dma->rx.phys, UARTDM_RX_SIZE, dma->dir);
+ dma_unmap_sg(port->dev, &dma->sg, 1, dma->dir);
+ sg_init_table(&dma->sg, 1);
for (i = 0; i < count; i++) {
char flag = TTY_NORMAL;
- if (msm_port->break_detected && dma->rx.virt[i] == 0) {
+ if (msm_port->break_detected && dma->virt[i] == 0) {
port->icount.brk++;
flag = TTY_BREAK;
msm_port->break_detected = false;
@@ -604,9 +588,9 @@ static void msm_complete_rx_dma(void *args)
if (!(port->read_status_mask & MSM_UART_SR_RX_BREAK))
flag = TTY_NORMAL;
- sysrq = uart_prepare_sysrq_char(port, dma->rx.virt[i]);
+ sysrq = uart_prepare_sysrq_char(port, dma->virt[i]);
if (!sysrq)
- tty_insert_flip_char(tport, dma->rx.virt[i], flag);
+ tty_insert_flip_char(tport, dma->virt[i], flag);
}
msm_start_rx_dma(msm_port);
@@ -630,14 +614,13 @@ static void msm_start_rx_dma(struct msm_port *msm_port)
if (!dma->chan)
return;
- dma->rx.phys = dma_map_single(uart->dev, dma->rx.virt,
- UARTDM_RX_SIZE, dma->dir);
- ret = dma_mapping_error(uart->dev, dma->rx.phys);
- if (ret)
+ sg_init_one(&dma->sg, dma->virt, UARTDM_RX_SIZE);
+ ret = dma_map_sg(uart->dev, &dma->sg, 1, dma->dir);
+ if (!ret)
goto sw_mode;
- dma->desc = dmaengine_prep_slave_single(dma->chan, dma->rx.phys,
- UARTDM_RX_SIZE, DMA_DEV_TO_MEM,
+ dma->desc = dmaengine_prep_slave_sg(dma->chan, &dma->sg, 1,
+ DMA_DEV_TO_MEM,
DMA_PREP_INTERRUPT);
if (!dma->desc)
goto unmap;
@@ -664,8 +647,6 @@ static void msm_start_rx_dma(struct msm_port *msm_port)
msm_write(uart, msm_port->imr, MSM_UART_IMR);
- dma->rx.count = UARTDM_RX_SIZE;
-
dma_async_issue_pending(dma->chan);
msm_write(uart, MSM_UART_CR_CMD_RESET_STALE_INT, MSM_UART_CR);
@@ -684,7 +665,8 @@ static void msm_start_rx_dma(struct msm_port *msm_port)
return;
unmap:
- dma_unmap_single(uart->dev, dma->rx.phys, UARTDM_RX_SIZE, dma->dir);
+ dma_unmap_sg(uart->dev, &dma->sg, 1, dma->dir);
+ sg_init_table(&dma->sg, 1);
sw_mode:
/*
@@ -967,7 +949,7 @@ static irqreturn_t msm_uart_irq(int irq, void *dev_id)
}
if (misr & (MSM_UART_IMR_RXLEV | MSM_UART_IMR_RXSTALE)) {
- if (dma->rx.count) {
+ if (sg_dma_len(&dma->sg)) {
val = MSM_UART_CR_CMD_STALE_EVENT_DISABLE;
msm_write(port, val, MSM_UART_CR);
val = MSM_UART_CR_CMD_RESET_STALE_INT;