Re: [PATCH] serial: Use -EAGAIN in getc and putc

On 12/4/22 13:36, Pali Rohár wrote:

U-Boot serial code already handles -EAGAIN value from getc and putc callbacks. So change drivers code to return -EAGAIN when HW is busy instead of doing its own busy loop and waiting until HW is ready.

Signed-off-by: Pali Rohár pali@kernel.org

Reviewed-by: Stefan Roese sr@denx.de

Thanks, Stefan

---

drivers/serial/serial_arc.c | 8 ++++---- drivers/serial/serial_lpuart.c | 8 ++++---- drivers/serial/serial_mvebu_a3700.c | 8 ++++---- 3 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/drivers/serial/serial_arc.c b/drivers/serial/serial_arc.c index b2d95bdbe18d..c2fc8a901e25 100644 --- a/drivers/serial/serial_arc.c +++ b/drivers/serial/serial_arc.c @@ -53,8 +53,8 @@ static int arc_serial_putc(struct udevice *dev, const char c) struct arc_serial_plat *plat = dev_get_plat(dev); struct arc_serial_regs *const regs = plat->reg;

• while (!(readb(&regs->status) & UART_TXEMPTY))

• ;
  

• if (!(readb(&regs->status) & UART_TXEMPTY))

• return -EAGAIN;
  
  

  writeb(c, &regs->data);

@@ -83,8 +83,8 @@ static int arc_serial_getc(struct udevice *dev) struct arc_serial_plat *plat = dev_get_plat(dev); struct arc_serial_regs *const regs = plat->reg;

• while (!arc_serial_tstc(regs))

• ;
  

• if (!arc_serial_tstc(regs))

• return -EAGAIN;
  
  

  /* Check for overflow errors */ if (readb(&regs->status) & UART_OVERFLOW_ERR)

diff --git a/drivers/serial/serial_lpuart.c b/drivers/serial/serial_lpuart.c index ff576da516d4..d7259d531b55 100644 --- a/drivers/serial/serial_lpuart.c +++ b/drivers/serial/serial_lpuart.c @@ -168,8 +168,8 @@ static void _lpuart_serial_setbrg(struct udevice *dev, static int _lpuart_serial_getc(struct lpuart_serial_plat *plat) { struct lpuart_fsl *base = plat->reg;

• while (!(__raw_readb(&base->us1) & (US1_RDRF | US1_OR)))

• schedule();
  

• if (!(__raw_readb(&base->us1) & (US1_RDRF | US1_OR)))

• return -EAGAIN;
  
  

  barrier();

@@ -181,8 +181,8 @@ static void _lpuart_serial_putc(struct lpuart_serial_plat *plat, { struct lpuart_fsl *base = plat->reg;

• while (!(__raw_readb(&base->us1) & US1_TDRE))

• schedule();
  

• if (!(__raw_readb(&base->us1) & US1_TDRE))

• return -EAGAIN;
  
  

  __raw_writeb(c, &base->ud); }

diff --git a/drivers/serial/serial_mvebu_a3700.c b/drivers/serial/serial_mvebu_a3700.c index 0fcd7e88acee..b2017c645565 100644 --- a/drivers/serial/serial_mvebu_a3700.c +++ b/drivers/serial/serial_mvebu_a3700.c @@ -40,8 +40,8 @@ static int mvebu_serial_putc(struct udevice *dev, const char ch) struct mvebu_plat *plat = dev_get_plat(dev); void __iomem *base = plat->base;

• while (readl(base + UART_STATUS_REG) & UART_STATUS_TXFIFO_FULL)

• ;
  

• if (readl(base + UART_STATUS_REG) & UART_STATUS_TXFIFO_FULL)

• return -EAGAIN;
  
  

  writel(ch, base + UART_TX_REG);

@@ -53,8 +53,8 @@ static int mvebu_serial_getc(struct udevice *dev) struct mvebu_plat *plat = dev_get_plat(dev); void __iomem *base = plat->base;

• while (!(readl(base + UART_STATUS_REG) & UART_STATUS_RX_RDY))

• ;
  

• if (!(readl(base + UART_STATUS_REG) & UART_STATUS_RX_RDY))

• return -EAGAIN;
  
  

  return readl(base + UART_RX_REG) & 0xff; }

Viele Grüße, Stefan Roese