From ad725073d1666d94a96fbf9cba03777c3d58de24 Mon Sep 17 00:00:00 2001 From: Loic Poulain Date: Thu, 12 Jan 2023 18:19:51 +0100 Subject: [PATCH] serial: mxc: Speed-up character transmission MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Instead of waiting for empty FIFO condition before writing a character, wait for non-full FIFO condition. This helps in saving several tens of milliseconds during boot (depending verbosity). Signed-off-by: Loic Poulain Tested-by: Lothar Waßmann Acked-by: Pali Rohár Reviewed-by: Fabio Estevam Tested-by: Fabio Estevam --- drivers/serial/serial_mxc.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/serial/serial_mxc.c b/drivers/serial/serial_mxc.c index e4ffa9c3f6..cc85a50272 100644 --- a/drivers/serial/serial_mxc.c +++ b/drivers/serial/serial_mxc.c @@ -240,11 +240,11 @@ static void mxc_serial_putc(const char c) if (c == '\n') serial_putc('\r'); - writel(c, &mxc_base->txd); - /* wait for transmitter to be ready */ - while (!(readl(&mxc_base->ts) & UTS_TXEMPTY)) + while (readl(&mxc_base->ts) & UTS_TXFULL) schedule(); + + writel(c, &mxc_base->txd); } /* Test whether a character is in the RX buffer */ @@ -335,7 +335,7 @@ static int mxc_serial_putc(struct udevice *dev, const char ch) struct mxc_serial_plat *plat = dev_get_plat(dev); struct mxc_uart *const uart = plat->reg; - if (!(readl(&uart->ts) & UTS_TXEMPTY)) + if (readl(&uart->ts) & UTS_TXFULL) return -EAGAIN; writel(ch, &uart->txd); -- 2.39.5