These changes are a raw update to a vanilla kernel 4.1.10, with the

[kvmfornfv.git] / kernel / drivers / tty / serial / samsung.c

diff --git a/kernel/drivers/tty/serial/samsung.c b/kernel/drivers/tty/serial/samsung.c
index a0ae942..1e0d9b8 100644 (file)
--- a/kernel/drivers/tty/serial/samsung.c
+++ b/kernel/drivers/tty/serial/samsung.c
@@ -295,15 +295,6 @@ static int s3c24xx_serial_start_tx_dma(struct s3c24xx_uart_port *ourport,
        if (ourport->tx_mode != S3C24XX_TX_DMA)
                enable_tx_dma(ourport);
 
-       while (xmit->tail & (dma_get_cache_alignment() - 1)) {
-               if (rd_regl(port, S3C2410_UFSTAT) & ourport->info->tx_fifofull)
-                       return 0;
-               wr_regb(port, S3C2410_UTXH, xmit->buf[xmit->tail]);
-               xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-               port->icount.tx++;
-               count--;
-       }
-
        dma->tx_size = count & ~(dma_get_cache_alignment() - 1);
        dma->tx_transfer_addr = dma->tx_addr + xmit->tail;
 
@@ -342,7 +333,9 @@ static void s3c24xx_serial_start_next_tx(struct s3c24xx_uart_port *ourport)
                return;
        }
 
-       if (!ourport->dma || !ourport->dma->tx_chan || count < port->fifosize)
+       if (!ourport->dma || !ourport->dma->tx_chan ||
+           count < ourport->min_dma_size ||
+           xmit->tail & (dma_get_cache_alignment() - 1))
                s3c24xx_serial_start_tx_pio(ourport);
        else
                s3c24xx_serial_start_tx_dma(ourport, count);
@@ -736,15 +729,20 @@ static irqreturn_t s3c24xx_serial_tx_chars(int irq, void *id)
        struct uart_port *port = &ourport->port;
        struct circ_buf *xmit = &port->state->xmit;
        unsigned long flags;
-       int count;
+       int count, dma_count = 0;
 
        spin_lock_irqsave(&port->lock, flags);
 
        count = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
 
-       if (ourport->dma && ourport->dma->tx_chan && count >= port->fifosize) {
-               s3c24xx_serial_start_tx_dma(ourport, count);
-               goto out;
+       if (ourport->dma && ourport->dma->tx_chan &&
+           count >= ourport->min_dma_size) {
+               int align = dma_get_cache_alignment() -
+                       (xmit->tail & (dma_get_cache_alignment() - 1));
+               if (count-align >= ourport->min_dma_size) {
+                       dma_count = count-align;
+                       count = align;
+               }
        }
 
        if (port->x_char) {
@@ -765,14 +763,24 @@ static irqreturn_t s3c24xx_serial_tx_chars(int irq, void *id)
 
        /* try and drain the buffer... */
 
-       count = port->fifosize;
-       while (!uart_circ_empty(xmit) && count-- > 0) {
+       if (count > port->fifosize) {
+               count = port->fifosize;
+               dma_count = 0;
+       }
+
+       while (!uart_circ_empty(xmit) && count > 0) {
                if (rd_regl(port, S3C2410_UFSTAT) & ourport->info->tx_fifofull)
                        break;
 
                wr_regb(port, S3C2410_UTXH, xmit->buf[xmit->tail]);
                xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
                port->icount.tx++;
+               count--;
+       }
+
+       if (!count && dma_count) {
+               s3c24xx_serial_start_tx_dma(ourport, dma_count);
+               goto out;
        }
 
        if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) {
@@ -1838,6 +1846,13 @@ static int s3c24xx_serial_probe(struct platform_device *pdev)
        else if (ourport->info->fifosize)
                ourport->port.fifosize = ourport->info->fifosize;
 
+       /*
+        * DMA transfers must be aligned at least to cache line size,
+        * so find minimal transfer size suitable for DMA mode
+        */
+       ourport->min_dma_size = max_t(int, ourport->port.fifosize,
+                                   dma_get_cache_alignment());
+
        probe_index++;
 
        dbg("%s: initialising port %p...\n", __func__, ourport);