| Message ID | 20221204123655.29939-1-pali@kernel.org |
|---|---|
| State | Changes Requested |
| Delegated to: | Tom Rini |
| Headers | show |
| Series | serial: Use -EAGAIN in getc and putc | expand |
On Mon, 5 Dec 2022 at 01:37, Pali Rohár <pali@kernel.org> 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> > --- > 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(-) Reviewed-by: Simon Glass <sjg@chromium.org>
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(®s->status) & UART_TXEMPTY)) > - ; > + if (!(readb(®s->status) & UART_TXEMPTY)) > + return -EAGAIN; > > writeb(c, ®s->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(®s->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
On Sun, Dec 04, 2022 at 01:36:55PM +0100, 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: Simon Glass <sjg@chromium.org> > Reviewed-by: Stefan Roese <sr@denx.de> [snip] > 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); > } This is non-trivially not right for this driver. ->putc here is set to lpuart_serial_putc which calls _lpuart_serial_putc OR _lpuart32_serial_putc, so there's the lpuart32 cases to address, and then lpuart_serial_putc needs to just return whatever one it called rather than always returning 0.
On Thursday 08 December 2022 10:45:49 Tom Rini wrote: > On Sun, Dec 04, 2022 at 01:36:55PM +0100, 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: Simon Glass <sjg@chromium.org> > > Reviewed-by: Stefan Roese <sr@denx.de> > [snip] > > 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); > > } > > This is non-trivially not right for this driver. ->putc here is set to > lpuart_serial_putc which calls _lpuart_serial_putc OR > _lpuart32_serial_putc, so there's the lpuart32 cases to address, and > then lpuart_serial_putc needs to just return whatever one it called > rather than always returning 0. > > -- > Tom Ou, you are right. This is really incomplete and does not work correctly. Thanks for spotting this issue, I will send fixed patch.
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(®s->status) & UART_TXEMPTY)) - ; + if (!(readb(®s->status) & UART_TXEMPTY)) + return -EAGAIN; writeb(c, ®s->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(®s->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; }
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> --- 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(-)