Merge tag 'gpio-v4.5-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux...

[cascardo/linux.git] / drivers / tty / serial / sc16is7xx.c

diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index cc86c34..13f8d5f 100644 (file)
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -389,6 +389,13 @@ static void sc16is7xx_fifo_write(struct uart_port *port, u8 to_send)
        const u8 line = sc16is7xx_line(port);
        u8 addr = (SC16IS7XX_THR_REG << SC16IS7XX_REG_SHIFT) | line;
 
+       /*
+        * Don't send zero-length data, at least on SPI it confuses the chip
+        * delivering wrong TXLVL data.
+        */
+       if (unlikely(!to_send))
+               return;
+
        regcache_cache_bypass(s->regmap, true);
        regmap_raw_write(s->regmap, addr, s->buf, to_send);
        regcache_cache_bypass(s->regmap, false);
@@ -630,6 +637,12 @@ static void sc16is7xx_handle_tx(struct uart_port *port)
        if (likely(to_send)) {
                /* Limit to size of TX FIFO */
                txlen = sc16is7xx_port_read(port, SC16IS7XX_TXLVL_REG);
+               if (txlen > SC16IS7XX_FIFO_SIZE) {
+                       dev_err_ratelimited(port->dev,
+                               "chip reports %d free bytes in TX fifo, but it only has %d",
+                               txlen, SC16IS7XX_FIFO_SIZE);
+                       txlen = 0;
+               }
                to_send = (to_send > txlen) ? txlen : to_send;
 
                /* Add data to send */