* Re: [PATCH] serial: Use -EAGAIN in getc and putc
2022-12-04 12:36 [PATCH] serial: Use -EAGAIN in getc and putc Pali Rohár
2022-12-04 21:16 ` Simon Glass
@ 2022-12-05 6:20 ` Stefan Roese
2022-12-08 15:45 ` Tom Rini
2022-12-10 23:31 ` [PATCH v2] " Pali Rohár
3 siblings, 0 replies; 7+ messages in thread
From: Stefan Roese @ 2022-12-05 6:20 UTC (permalink / raw)
To: Pali Rohár; +Cc: u-boot, Simon Glass
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
--
DENX Software Engineering GmbH, Managing Director: Erika Unter
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-51 Fax: (+49)-8142-66989-80 Email: sr@denx.de
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH] serial: Use -EAGAIN in getc and putc
2022-12-04 12:36 [PATCH] serial: Use -EAGAIN in getc and putc Pali Rohár
2022-12-04 21:16 ` Simon Glass
2022-12-05 6:20 ` Stefan Roese
@ 2022-12-08 15:45 ` Tom Rini
2022-12-10 23:08 ` Pali Rohár
2022-12-10 23:31 ` [PATCH v2] " Pali Rohár
3 siblings, 1 reply; 7+ messages in thread
From: Tom Rini @ 2022-12-08 15:45 UTC (permalink / raw)
To: Pali Rohár; +Cc: Stefan Roese, u-boot, Simon Glass
[-- Attachment #1: Type: text/plain, Size: 1643 bytes --]
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
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^ permalink raw reply [flat|nested] 7+ messages in thread* [PATCH v2] serial: Use -EAGAIN in getc and putc
2022-12-04 12:36 [PATCH] serial: Use -EAGAIN in getc and putc Pali Rohár
` (2 preceding siblings ...)
2022-12-08 15:45 ` Tom Rini
@ 2022-12-10 23:31 ` Pali Rohár
2023-01-03 15:42 ` Tom Rini
3 siblings, 1 reply; 7+ messages in thread
From: Pali Rohár @ 2022-12-10 23:31 UTC (permalink / raw)
To: Stefan Roese, Simon Glass, Tom Rini; +Cc: u-boot
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>
---
Changes in v2:
* Fix serial_lpuart.c code after Tom's review
* Add serial_mpc8xx.c change
To prevent merge conflicts, please apply this patch *after* this:
http://patchwork.ozlabs.org/project/uboot/patch/20221210232744.15600-1-pali@kernel.org/
---
drivers/serial/serial_arc.c | 8 +++----
drivers/serial/serial_lpuart.c | 36 ++++++++++++-----------------
drivers/serial/serial_mpc8xx.c | 12 ++++------
drivers/serial/serial_mvebu_a3700.c | 8 +++----
4 files changed, 28 insertions(+), 36 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 07941c29ed74..51e66abdbc15 100644
--- a/drivers/serial/serial_lpuart.c
+++ b/drivers/serial/serial_lpuart.c
@@ -168,23 +168,24 @@ 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();
return __raw_readb(&base->ud);
}
-static void _lpuart_serial_putc(struct lpuart_serial_plat *plat,
+static int _lpuart_serial_putc(struct lpuart_serial_plat *plat,
const char c)
{
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);
+ return 0;
}
/* Test whether a character is in the RX buffer */
@@ -328,10 +329,9 @@ static int _lpuart32_serial_getc(struct lpuart_serial_plat *plat)
u32 stat, val;
lpuart_read32(plat->flags, &base->stat, &stat);
- while ((stat & STAT_RDRF) == 0) {
+ if ((stat & STAT_RDRF) == 0) {
lpuart_write32(plat->flags, &base->stat, STAT_FLAGS);
- schedule();
- lpuart_read32(plat->flags, &base->stat, &stat);
+ return -EAGAIN;
}
lpuart_read32(plat->flags, &base->data, &val);
@@ -343,22 +343,18 @@ static int _lpuart32_serial_getc(struct lpuart_serial_plat *plat)
return val & 0x3ff;
}
-static void _lpuart32_serial_putc(struct lpuart_serial_plat *plat,
+static int _lpuart32_serial_putc(struct lpuart_serial_plat *plat,
const char c)
{
struct lpuart_fsl_reg32 *base = plat->reg;
u32 stat;
- while (true) {
- lpuart_read32(plat->flags, &base->stat, &stat);
-
- if ((stat & STAT_TDRE))
- break;
-
- schedule();
- }
+ lpuart_read32(plat->flags, &base->stat, &stat);
+ if (!(stat & STAT_TDRE))
+ return -EAGAIN;
lpuart_write32(plat->flags, &base->data, c);
+ return 0;
}
/* Test whether a character is in the RX buffer */
@@ -453,11 +449,9 @@ static int lpuart_serial_putc(struct udevice *dev, const char c)
struct lpuart_serial_plat *plat = dev_get_plat(dev);
if (is_lpuart32(dev))
- _lpuart32_serial_putc(plat, c);
- else
- _lpuart_serial_putc(plat, c);
+ return _lpuart32_serial_putc(plat, c);
- return 0;
+ return _lpuart_serial_putc(plat, c);
}
static int lpuart_serial_pending(struct udevice *dev, bool input)
diff --git a/drivers/serial/serial_mpc8xx.c b/drivers/serial/serial_mpc8xx.c
index 808a40f503ea..b8d6a81b650f 100644
--- a/drivers/serial/serial_mpc8xx.c
+++ b/drivers/serial/serial_mpc8xx.c
@@ -178,14 +178,13 @@ static int serial_mpc8xx_putc(struct udevice *dev, const char c)
rtx = (struct serialbuffer __iomem *)&cpmp->cp_dpmem[CPM_SERIAL_BASE];
- /* Wait for last character to go. */
+ if (in_be16(&rtx->txbd.cbd_sc) & BD_SC_READY)
+ return -EAGAIN;
+
out_8(&rtx->txbuf, c);
out_be16(&rtx->txbd.cbd_datlen, 1);
setbits_be16(&rtx->txbd.cbd_sc, BD_SC_READY);
- while (in_be16(&rtx->txbd.cbd_sc) & BD_SC_READY)
- schedule();
-
return 0;
}
@@ -199,9 +198,8 @@ static int serial_mpc8xx_getc(struct udevice *dev)
rtx = (struct serialbuffer __iomem *)&cpmp->cp_dpmem[CPM_SERIAL_BASE];
- /* Wait for character to show up. */
- while (in_be16(&rtx->rxbd.cbd_sc) & BD_SC_EMPTY)
- schedule();
+ if (in_be16(&rtx->rxbd.cbd_sc) & BD_SC_EMPTY)
+ return -EAGAIN;
/* the characters are read one by one,
* use the rxindex to know the next char to deliver
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;
}
--
2.20.1
^ permalink raw reply related [flat|nested] 7+ messages in thread