* [PATCH 1/2] spi/pl022: timeout on polled transfer v2
@ 2011-05-19 16:05 ` Linus Walleij
0 siblings, 0 replies; 12+ messages in thread
From: Linus Walleij @ 2011-05-19 16:05 UTC (permalink / raw)
To: Grant Likely, spi-devel-general
Cc: Linus Walleij, Lee Jones, linux-arm-kernel, Magnus Templing
From: Magnus Templing <magnus.templing@stericsson.com>
This adds the missing handling of polling timeouts and deletes
our last todo.
Signed-off-by: Magnus Templing <magnus.templing@stericsson.com>
Reviewed-by: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com>
[Fixups from review by Wolfram Sang]
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
drivers/spi/amba-pl022.c | 23 +++++++++++++++--------
1 files changed, 15 insertions(+), 8 deletions(-)
diff --git a/drivers/spi/amba-pl022.c b/drivers/spi/amba-pl022.c
index 08de58e..18667de 100644
--- a/drivers/spi/amba-pl022.c
+++ b/drivers/spi/amba-pl022.c
@@ -24,11 +24,6 @@
* GNU General Public License for more details.
*/
-/*
- * TODO:
- * - add timeout on polled transfers
- */
-
#include <linux/init.h>
#include <linux/module.h>
#include <linux/device.h>
@@ -287,6 +282,8 @@
#define CLEAR_ALL_INTERRUPTS 0x3
+#define SPI_POLLING_TIMEOUT 1000
+
/*
* The type of reading going on on this chip
@@ -1378,6 +1375,7 @@ static void do_polling_transfer(struct pl022 *pl022)
struct spi_transfer *transfer = NULL;
struct spi_transfer *previous = NULL;
struct chip_data *chip;
+ unsigned long time, timeout;
chip = pl022->cur_chip;
message = pl022->cur_msg;
@@ -1415,9 +1413,18 @@ static void do_polling_transfer(struct pl022 *pl022)
SSP_CR1(pl022->virtbase));
dev_dbg(&pl022->adev->dev, "polling transfer ongoing ...\n");
- /* FIXME: insert a timeout so we don't hang here indefinitely */
- while (pl022->tx < pl022->tx_end || pl022->rx < pl022->rx_end)
+
+ timeout = jiffies + msecs_to_jiffies(SPI_POLLING_TIMEOUT);
+ while (pl022->tx < pl022->tx_end || pl022->rx < pl022->rx_end) {
+ time = jiffies;
readwriter(pl022);
+ if (time_after(time, timeout)) {
+ dev_warn(&pl022->adev->dev,
+ "%s: timeout!\n", __func__);
+ message->state = STATE_ERROR;
+ goto out;
+ }
+ }
/* Update total byte transferred */
message->actual_length += pl022->cur_transfer->len;
@@ -1426,7 +1433,7 @@ static void do_polling_transfer(struct pl022 *pl022)
/* Move to next transfer */
message->state = next_transfer(pl022);
}
-
+out:
/* Handle end of message */
if (message->state == STATE_DONE)
message->status = 0;
--
1.7.3.2
^ permalink raw reply related [flat|nested] 12+ messages in thread
* [PATCH 1/2] spi/pl022: timeout on polled transfer v2
@ 2011-05-19 16:05 ` Linus Walleij
0 siblings, 0 replies; 12+ messages in thread
From: Linus Walleij @ 2011-05-19 16:05 UTC (permalink / raw)
To: linux-arm-kernel
From: Magnus Templing <magnus.templing@stericsson.com>
This adds the missing handling of polling timeouts and deletes
our last todo.
Signed-off-by: Magnus Templing <magnus.templing@stericsson.com>
Reviewed-by: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com>
[Fixups from review by Wolfram Sang]
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
drivers/spi/amba-pl022.c | 23 +++++++++++++++--------
1 files changed, 15 insertions(+), 8 deletions(-)
diff --git a/drivers/spi/amba-pl022.c b/drivers/spi/amba-pl022.c
index 08de58e..18667de 100644
--- a/drivers/spi/amba-pl022.c
+++ b/drivers/spi/amba-pl022.c
@@ -24,11 +24,6 @@
* GNU General Public License for more details.
*/
-/*
- * TODO:
- * - add timeout on polled transfers
- */
-
#include <linux/init.h>
#include <linux/module.h>
#include <linux/device.h>
@@ -287,6 +282,8 @@
#define CLEAR_ALL_INTERRUPTS 0x3
+#define SPI_POLLING_TIMEOUT 1000
+
/*
* The type of reading going on on this chip
@@ -1378,6 +1375,7 @@ static void do_polling_transfer(struct pl022 *pl022)
struct spi_transfer *transfer = NULL;
struct spi_transfer *previous = NULL;
struct chip_data *chip;
+ unsigned long time, timeout;
chip = pl022->cur_chip;
message = pl022->cur_msg;
@@ -1415,9 +1413,18 @@ static void do_polling_transfer(struct pl022 *pl022)
SSP_CR1(pl022->virtbase));
dev_dbg(&pl022->adev->dev, "polling transfer ongoing ...\n");
- /* FIXME: insert a timeout so we don't hang here indefinitely */
- while (pl022->tx < pl022->tx_end || pl022->rx < pl022->rx_end)
+
+ timeout = jiffies + msecs_to_jiffies(SPI_POLLING_TIMEOUT);
+ while (pl022->tx < pl022->tx_end || pl022->rx < pl022->rx_end) {
+ time = jiffies;
readwriter(pl022);
+ if (time_after(time, timeout)) {
+ dev_warn(&pl022->adev->dev,
+ "%s: timeout!\n", __func__);
+ message->state = STATE_ERROR;
+ goto out;
+ }
+ }
/* Update total byte transferred */
message->actual_length += pl022->cur_transfer->len;
@@ -1426,7 +1433,7 @@ static void do_polling_transfer(struct pl022 *pl022)
/* Move to next transfer */
message->state = next_transfer(pl022);
}
-
+out:
/* Handle end of message */
if (message->state == STATE_DONE)
message->status = 0;
--
1.7.3.2
^ permalink raw reply related [flat|nested] 12+ messages in thread
* Re: [PATCH 1/2] spi/pl022: timeout on polled transfer v2
2011-05-19 16:05 ` Linus Walleij
@ 2011-05-19 16:55 ` Grant Likely
-1 siblings, 0 replies; 12+ messages in thread
From: Grant Likely @ 2011-05-19 16:55 UTC (permalink / raw)
To: Linus Walleij
Cc: spi-devel-general, Linus Walleij, Lee Jones, linux-arm-kernel,
Magnus Templing
On Thu, May 19, 2011 at 06:05:34PM +0200, Linus Walleij wrote:
> From: Magnus Templing <magnus.templing@stericsson.com>
>
> This adds the missing handling of polling timeouts and deletes
> our last todo.
>
> Signed-off-by: Magnus Templing <magnus.templing@stericsson.com>
> Reviewed-by: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com>
> [Fixups from review by Wolfram Sang]
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Applied, thanks.
g.
> ---
> drivers/spi/amba-pl022.c | 23 +++++++++++++++--------
> 1 files changed, 15 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/spi/amba-pl022.c b/drivers/spi/amba-pl022.c
> index 08de58e..18667de 100644
> --- a/drivers/spi/amba-pl022.c
> +++ b/drivers/spi/amba-pl022.c
> @@ -24,11 +24,6 @@
> * GNU General Public License for more details.
> */
>
> -/*
> - * TODO:
> - * - add timeout on polled transfers
> - */
> -
> #include <linux/init.h>
> #include <linux/module.h>
> #include <linux/device.h>
> @@ -287,6 +282,8 @@
>
> #define CLEAR_ALL_INTERRUPTS 0x3
>
> +#define SPI_POLLING_TIMEOUT 1000
> +
>
> /*
> * The type of reading going on on this chip
> @@ -1378,6 +1375,7 @@ static void do_polling_transfer(struct pl022 *pl022)
> struct spi_transfer *transfer = NULL;
> struct spi_transfer *previous = NULL;
> struct chip_data *chip;
> + unsigned long time, timeout;
>
> chip = pl022->cur_chip;
> message = pl022->cur_msg;
> @@ -1415,9 +1413,18 @@ static void do_polling_transfer(struct pl022 *pl022)
> SSP_CR1(pl022->virtbase));
>
> dev_dbg(&pl022->adev->dev, "polling transfer ongoing ...\n");
> - /* FIXME: insert a timeout so we don't hang here indefinitely */
> - while (pl022->tx < pl022->tx_end || pl022->rx < pl022->rx_end)
> +
> + timeout = jiffies + msecs_to_jiffies(SPI_POLLING_TIMEOUT);
> + while (pl022->tx < pl022->tx_end || pl022->rx < pl022->rx_end) {
> + time = jiffies;
> readwriter(pl022);
> + if (time_after(time, timeout)) {
> + dev_warn(&pl022->adev->dev,
> + "%s: timeout!\n", __func__);
> + message->state = STATE_ERROR;
> + goto out;
> + }
> + }
>
> /* Update total byte transferred */
> message->actual_length += pl022->cur_transfer->len;
> @@ -1426,7 +1433,7 @@ static void do_polling_transfer(struct pl022 *pl022)
> /* Move to next transfer */
> message->state = next_transfer(pl022);
> }
> -
> +out:
> /* Handle end of message */
> if (message->state == STATE_DONE)
> message->status = 0;
> --
> 1.7.3.2
>
^ permalink raw reply [flat|nested] 12+ messages in thread
* [PATCH 1/2] spi/pl022: timeout on polled transfer v2
@ 2011-05-19 16:55 ` Grant Likely
0 siblings, 0 replies; 12+ messages in thread
From: Grant Likely @ 2011-05-19 16:55 UTC (permalink / raw)
To: linux-arm-kernel
On Thu, May 19, 2011 at 06:05:34PM +0200, Linus Walleij wrote:
> From: Magnus Templing <magnus.templing@stericsson.com>
>
> This adds the missing handling of polling timeouts and deletes
> our last todo.
>
> Signed-off-by: Magnus Templing <magnus.templing@stericsson.com>
> Reviewed-by: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com>
> [Fixups from review by Wolfram Sang]
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Applied, thanks.
g.
> ---
> drivers/spi/amba-pl022.c | 23 +++++++++++++++--------
> 1 files changed, 15 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/spi/amba-pl022.c b/drivers/spi/amba-pl022.c
> index 08de58e..18667de 100644
> --- a/drivers/spi/amba-pl022.c
> +++ b/drivers/spi/amba-pl022.c
> @@ -24,11 +24,6 @@
> * GNU General Public License for more details.
> */
>
> -/*
> - * TODO:
> - * - add timeout on polled transfers
> - */
> -
> #include <linux/init.h>
> #include <linux/module.h>
> #include <linux/device.h>
> @@ -287,6 +282,8 @@
>
> #define CLEAR_ALL_INTERRUPTS 0x3
>
> +#define SPI_POLLING_TIMEOUT 1000
> +
>
> /*
> * The type of reading going on on this chip
> @@ -1378,6 +1375,7 @@ static void do_polling_transfer(struct pl022 *pl022)
> struct spi_transfer *transfer = NULL;
> struct spi_transfer *previous = NULL;
> struct chip_data *chip;
> + unsigned long time, timeout;
>
> chip = pl022->cur_chip;
> message = pl022->cur_msg;
> @@ -1415,9 +1413,18 @@ static void do_polling_transfer(struct pl022 *pl022)
> SSP_CR1(pl022->virtbase));
>
> dev_dbg(&pl022->adev->dev, "polling transfer ongoing ...\n");
> - /* FIXME: insert a timeout so we don't hang here indefinitely */
> - while (pl022->tx < pl022->tx_end || pl022->rx < pl022->rx_end)
> +
> + timeout = jiffies + msecs_to_jiffies(SPI_POLLING_TIMEOUT);
> + while (pl022->tx < pl022->tx_end || pl022->rx < pl022->rx_end) {
> + time = jiffies;
> readwriter(pl022);
> + if (time_after(time, timeout)) {
> + dev_warn(&pl022->adev->dev,
> + "%s: timeout!\n", __func__);
> + message->state = STATE_ERROR;
> + goto out;
> + }
> + }
>
> /* Update total byte transferred */
> message->actual_length += pl022->cur_transfer->len;
> @@ -1426,7 +1433,7 @@ static void do_polling_transfer(struct pl022 *pl022)
> /* Move to next transfer */
> message->state = next_transfer(pl022);
> }
> -
> +out:
> /* Handle end of message */
> if (message->state == STATE_DONE)
> message->status = 0;
> --
> 1.7.3.2
>
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH 1/2] spi/pl022: timeout on polled transfer v2
2011-05-19 16:05 ` Linus Walleij
@ 2011-05-19 17:04 ` Vitaly Wool
-1 siblings, 0 replies; 12+ messages in thread
From: Vitaly Wool @ 2011-05-19 17:04 UTC (permalink / raw)
To: Linus Walleij
Cc: Linus Walleij, Magnus Templing,
spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f, Lee Jones,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r
Hi Linus,
On Thu, May 19, 2011 at 6:05 PM, Linus Walleij
<linus.walleij-0IS4wlFg1OjSUeElwK9/Pw@public.gmane.org> wrote:
> From: Magnus Templing <magnus.templing-0IS4wlFg1OjSUeElwK9/Pw@public.gmane.org>
>
> This adds the missing handling of polling timeouts and deletes
> our last todo.
>
> Signed-off-by: Magnus Templing <magnus.templing-0IS4wlFg1OjSUeElwK9/Pw@public.gmane.org>
> Reviewed-by: Srinidhi Kasagar <srinidhi.kasagar-0IS4wlFg1OjSUeElwK9/Pw@public.gmane.org>
> [Fixups from review by Wolfram Sang]
> Signed-off-by: Linus Walleij <linus.walleij-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> ---
> drivers/spi/amba-pl022.c | 23 +++++++++++++++--------
> 1 files changed, 15 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/spi/amba-pl022.c b/drivers/spi/amba-pl022.c
> index 08de58e..18667de 100644
> --- a/drivers/spi/amba-pl022.c
> +++ b/drivers/spi/amba-pl022.c
> @@ -24,11 +24,6 @@
> * GNU General Public License for more details.
> */
>
> -/*
> - * TODO:
> - * - add timeout on polled transfers
> - */
> -
> #include <linux/init.h>
> #include <linux/module.h>
> #include <linux/device.h>
> @@ -287,6 +282,8 @@
>
> #define CLEAR_ALL_INTERRUPTS 0x3
>
> +#define SPI_POLLING_TIMEOUT 1000
> +
>
> /*
> * The type of reading going on on this chip
> @@ -1378,6 +1375,7 @@ static void do_polling_transfer(struct pl022 *pl022)
> struct spi_transfer *transfer = NULL;
> struct spi_transfer *previous = NULL;
> struct chip_data *chip;
> + unsigned long time, timeout;
>
> chip = pl022->cur_chip;
> message = pl022->cur_msg;
> @@ -1415,9 +1413,18 @@ static void do_polling_transfer(struct pl022 *pl022)
> SSP_CR1(pl022->virtbase));
>
> dev_dbg(&pl022->adev->dev, "polling transfer ongoing ...\n");
> - /* FIXME: insert a timeout so we don't hang here indefinitely */
> - while (pl022->tx < pl022->tx_end || pl022->rx < pl022->rx_end)
> +
> + timeout = jiffies + msecs_to_jiffies(SPI_POLLING_TIMEOUT);
> + while (pl022->tx < pl022->tx_end || pl022->rx < pl022->rx_end) {
> + time = jiffies;
> readwriter(pl022);
> + if (time_after(time, timeout)) {
> + dev_warn(&pl022->adev->dev,
> + "%s: timeout!\n", __func__);
> + message->state = STATE_ERROR;
> + goto out;
> + }
> + }
just out of curiosity: is it a busy wait? Looks like it is...
Thanks,
Vitaly
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^ permalink raw reply [flat|nested] 12+ messages in thread
* [PATCH 1/2] spi/pl022: timeout on polled transfer v2
@ 2011-05-19 17:04 ` Vitaly Wool
0 siblings, 0 replies; 12+ messages in thread
From: Vitaly Wool @ 2011-05-19 17:04 UTC (permalink / raw)
To: linux-arm-kernel
Hi Linus,
On Thu, May 19, 2011 at 6:05 PM, Linus Walleij
<linus.walleij@stericsson.com> wrote:
> From: Magnus Templing <magnus.templing@stericsson.com>
>
> This adds the missing handling of polling timeouts and deletes
> our last todo.
>
> Signed-off-by: Magnus Templing <magnus.templing@stericsson.com>
> Reviewed-by: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com>
> [Fixups from review by Wolfram Sang]
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
> ---
> ?drivers/spi/amba-pl022.c | ? 23 +++++++++++++++--------
> ?1 files changed, 15 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/spi/amba-pl022.c b/drivers/spi/amba-pl022.c
> index 08de58e..18667de 100644
> --- a/drivers/spi/amba-pl022.c
> +++ b/drivers/spi/amba-pl022.c
> @@ -24,11 +24,6 @@
> ?* GNU General Public License for more details.
> ?*/
>
> -/*
> - * TODO:
> - * - add timeout on polled transfers
> - */
> -
> ?#include <linux/init.h>
> ?#include <linux/module.h>
> ?#include <linux/device.h>
> @@ -287,6 +282,8 @@
>
> ?#define CLEAR_ALL_INTERRUPTS ?0x3
>
> +#define SPI_POLLING_TIMEOUT 1000
> +
>
> ?/*
> ?* The type of reading going on on this chip
> @@ -1378,6 +1375,7 @@ static void do_polling_transfer(struct pl022 *pl022)
> ? ? ? ?struct spi_transfer *transfer = NULL;
> ? ? ? ?struct spi_transfer *previous = NULL;
> ? ? ? ?struct chip_data *chip;
> + ? ? ? unsigned long time, timeout;
>
> ? ? ? ?chip = pl022->cur_chip;
> ? ? ? ?message = pl022->cur_msg;
> @@ -1415,9 +1413,18 @@ static void do_polling_transfer(struct pl022 *pl022)
> ? ? ? ? ? ? ? ? ? ? ? SSP_CR1(pl022->virtbase));
>
> ? ? ? ? ? ? ? ?dev_dbg(&pl022->adev->dev, "polling transfer ongoing ...\n");
> - ? ? ? ? ? ? ? /* FIXME: insert a timeout so we don't hang here indefinitely */
> - ? ? ? ? ? ? ? while (pl022->tx < pl022->tx_end || pl022->rx < pl022->rx_end)
> +
> + ? ? ? ? ? ? ? timeout = jiffies + msecs_to_jiffies(SPI_POLLING_TIMEOUT);
> + ? ? ? ? ? ? ? while (pl022->tx < pl022->tx_end || pl022->rx < pl022->rx_end) {
> + ? ? ? ? ? ? ? ? ? ? ? time = jiffies;
> ? ? ? ? ? ? ? ? ? ? ? ?readwriter(pl022);
> + ? ? ? ? ? ? ? ? ? ? ? if (time_after(time, timeout)) {
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? dev_warn(&pl022->adev->dev,
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? "%s: timeout!\n", __func__);
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? message->state = STATE_ERROR;
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? goto out;
> + ? ? ? ? ? ? ? ? ? ? ? }
> + ? ? ? ? ? ? ? }
just out of curiosity: is it a busy wait? Looks like it is...
Thanks,
Vitaly
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH 1/2] spi/pl022: timeout on polled transfer v2
2011-05-19 17:04 ` Vitaly Wool
@ 2011-05-19 17:36 ` Linus Walleij
-1 siblings, 0 replies; 12+ messages in thread
From: Linus Walleij @ 2011-05-19 17:36 UTC (permalink / raw)
To: Vitaly Wool
Cc: Grant Likely, spi-devel-general, Lee Jones, linux-arm-kernel,
Magnus Templing
2011/5/19 Vitaly Wool <vitalywool@gmail.com>:
>> +
>> + timeout = jiffies + msecs_to_jiffies(SPI_POLLING_TIMEOUT);
>> + while (pl022->tx < pl022->tx_end || pl022->rx < pl022->rx_end) {
>> + time = jiffies;
>> readwriter(pl022);
>> + if (time_after(time, timeout)) {
>> + dev_warn(&pl022->adev->dev,
>> + "%s: timeout!\n", __func__);
>> + message->state = STATE_ERROR;
>> + goto out;
>> + }
>> + }
>
> just out of curiosity: is it a busy wait? Looks like it is...
Yep that's the polling mode part. IRQ and DMA mode should
be the norm I guess.
Magnus: do you have a specific use case for this thing?
Yours,
Linus Walleij
^ permalink raw reply [flat|nested] 12+ messages in thread
* [PATCH 1/2] spi/pl022: timeout on polled transfer v2
@ 2011-05-19 17:36 ` Linus Walleij
0 siblings, 0 replies; 12+ messages in thread
From: Linus Walleij @ 2011-05-19 17:36 UTC (permalink / raw)
To: linux-arm-kernel
2011/5/19 Vitaly Wool <vitalywool@gmail.com>:
>> +
>> + ? ? ? ? ? ? ? timeout = jiffies + msecs_to_jiffies(SPI_POLLING_TIMEOUT);
>> + ? ? ? ? ? ? ? while (pl022->tx < pl022->tx_end || pl022->rx < pl022->rx_end) {
>> + ? ? ? ? ? ? ? ? ? ? ? time = jiffies;
>> ? ? ? ? ? ? ? ? ? ? ? ?readwriter(pl022);
>> + ? ? ? ? ? ? ? ? ? ? ? if (time_after(time, timeout)) {
>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? dev_warn(&pl022->adev->dev,
>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? "%s: timeout!\n", __func__);
>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? message->state = STATE_ERROR;
>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? goto out;
>> + ? ? ? ? ? ? ? ? ? ? ? }
>> + ? ? ? ? ? ? ? }
>
> just out of curiosity: is it a busy wait? Looks like it is...
Yep that's the polling mode part. IRQ and DMA mode should
be the norm I guess.
Magnus: do you have a specific use case for this thing?
Yours,
Linus Walleij
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH 1/2] spi/pl022: timeout on polled transfer v2
2011-05-19 17:36 ` Linus Walleij
@ 2011-05-19 17:40 ` Vitaly Wool
-1 siblings, 0 replies; 12+ messages in thread
From: Vitaly Wool @ 2011-05-19 17:40 UTC (permalink / raw)
To: Linus Walleij
Cc: Grant Likely, spi-devel-general, Lee Jones, linux-arm-kernel,
Magnus Templing
On Thu, May 19, 2011 at 7:36 PM, Linus Walleij <linus.walleij@linaro.org> wrote:
>>
>> just out of curiosity: is it a busy wait? Looks like it is...
>
> Yep that's the polling mode part. IRQ and DMA mode should
> be the norm I guess.
>
> Magnus: do you have a specific use case for this thing?
Well, adding cpu_relax() somewhere in the loop might be not a bad idea...
Thanks,
Vitaly
^ permalink raw reply [flat|nested] 12+ messages in thread
* [PATCH 1/2] spi/pl022: timeout on polled transfer v2
@ 2011-05-19 17:40 ` Vitaly Wool
0 siblings, 0 replies; 12+ messages in thread
From: Vitaly Wool @ 2011-05-19 17:40 UTC (permalink / raw)
To: linux-arm-kernel
On Thu, May 19, 2011 at 7:36 PM, Linus Walleij <linus.walleij@linaro.org> wrote:
>>
>> just out of curiosity: is it a busy wait? Looks like it is...
>
> Yep that's the polling mode part. IRQ and DMA mode should
> be the norm I guess.
>
> Magnus: do you have a specific use case for this thing?
Well, adding cpu_relax() somewhere in the loop might be not a bad idea...
Thanks,
Vitaly
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH 1/2] spi/pl022: timeout on polled transfer v2
2011-05-19 17:40 ` Vitaly Wool
@ 2011-05-19 18:06 ` Linus Walleij
-1 siblings, 0 replies; 12+ messages in thread
From: Linus Walleij @ 2011-05-19 18:06 UTC (permalink / raw)
To: Vitaly Wool
Cc: Grant Likely, spi-devel-general, Lee Jones, linux-arm-kernel,
Magnus Templing
2011/5/19 Vitaly Wool <vitalywool@gmail.com>:
> On Thu, May 19, 2011 at 7:36 PM, Linus Walleij <linus.walleij@linaro.org> wrote:
>>>
>>> just out of curiosity: is it a busy wait? Looks like it is...
>>
>> Yep that's the polling mode part. IRQ and DMA mode should
>> be the norm I guess.
>>
>> Magnus: do you have a specific use case for this thing?
>
> Well, adding cpu_relax() somewhere in the loop might be not a bad idea...
OK sent a patch for it, and Grant applied it within something like
30 seconds :-)
I think on ARM that just boils down to a barrier() so it
basically injects air in the pipeline when busywaiting, I never
understood what that is good for, but it's a good marker anyway.
Linus Walleij
^ permalink raw reply [flat|nested] 12+ messages in thread
* [PATCH 1/2] spi/pl022: timeout on polled transfer v2
@ 2011-05-19 18:06 ` Linus Walleij
0 siblings, 0 replies; 12+ messages in thread
From: Linus Walleij @ 2011-05-19 18:06 UTC (permalink / raw)
To: linux-arm-kernel
2011/5/19 Vitaly Wool <vitalywool@gmail.com>:
> On Thu, May 19, 2011 at 7:36 PM, Linus Walleij <linus.walleij@linaro.org> wrote:
>>>
>>> just out of curiosity: is it a busy wait? Looks like it is...
>>
>> Yep that's the polling mode part. IRQ and DMA mode should
>> be the norm I guess.
>>
>> Magnus: do you have a specific use case for this thing?
>
> Well, adding cpu_relax() somewhere in the loop might be not a bad idea...
OK sent a patch for it, and Grant applied it within something like
30 seconds :-)
I think on ARM that just boils down to a barrier() so it
basically injects air in the pipeline when busywaiting, I never
understood what that is good for, but it's a good marker anyway.
Linus Walleij
^ permalink raw reply [flat|nested] 12+ messages in thread
end of thread, other threads:[~2011-05-19 18:06 UTC | newest]
Thread overview: 12+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2011-05-19 16:05 [PATCH 1/2] spi/pl022: timeout on polled transfer v2 Linus Walleij
2011-05-19 16:05 ` Linus Walleij
2011-05-19 16:55 ` Grant Likely
2011-05-19 16:55 ` Grant Likely
[not found] ` <1305821134-26147-1-git-send-email-linus.walleij-0IS4wlFg1OjSUeElwK9/Pw@public.gmane.org>
2011-05-19 17:04 ` Vitaly Wool
2011-05-19 17:04 ` Vitaly Wool
2011-05-19 17:36 ` Linus Walleij
2011-05-19 17:36 ` Linus Walleij
2011-05-19 17:40 ` Vitaly Wool
2011-05-19 17:40 ` Vitaly Wool
2011-05-19 18:06 ` Linus Walleij
2011-05-19 18:06 ` Linus Walleij
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