gpio: spear_gpio: Fix gpio_set_value() implementation

In current gpio_set_value() implementation, it always sets the gpio control bit no matter the value argument is 0 or 1. Thus the GPIOs never set to low. This patch fixes this bug.

Signed-off-by Axel Lin <[email protected]>

Acked-by Stefan Roese <[email protected]>

Reviewed-by Vipin Kumar <[email protected]>

---
This patch was sent on http://lists.denx.de/pipermail/u-boot/2013-June/156861.html

Has Stefan's Ack:
http://lists.denx.de/pipermail/u-boot/2013-June/156864.html

Vipin says the code is fine, so I add Vipin's review-by.
http://lists.denx.de/pipermail/u-boot/2013-June/156966.html

Michael confirms it works:
http://lists.denx.de/pipermail/u-boot/2013-August/160652.html

No body picks up this patch, so here is a resend.
Although I think this is a bug fix, but I'll let maintainers to determinate if this is the material for v2013.10.
Anyway, can someone at least let me know if this patch is ok for apply at some point? I have no idea who is maintaining this file.

Regards,
Axel

 drivers/gpio/spear_gpio.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

drivers/gpio/spear_gpio.c +0 -0

index 367b670..6fb4117 100644
@@ -36,7 +36,10 @@ int gpio_set_value(unsigned gpio, int value)
 {

Hi Axel,

Quoted 37 lines · Axel Lin

In current gpio_set_value() implementation, it always sets the gpio control bit no matter the value argument is 0 or 1. Thus the GPIOs never set to low. This patch fixes this bug.

Signed-off-by Axel Lin <[email protected]>

Acked-by Stefan Roese <[email protected]>

Reviewed-by Vipin Kumar <[email protected]>

---
This patch was sent on http://lists.denx.de/pipermail/u-boot/2013-June/156861.html

Has Stefan's Ack:
http://lists.denx.de/pipermail/u-boot/2013-June/156864.html

Vipin says the code is fine, so I add Vipin's review-by.
http://lists.denx.de/pipermail/u-boot/2013-June/156966.html

Michael confirms it works:
http://lists.denx.de/pipermail/u-boot/2013-August/160652.html

No body picks up this patch, so here is a resend.
Although I think this is a bug fix, but I'll let maintainers to determinate if this is the material for v2013.10.
Anyway, can someone at least let me know if this patch is ok for apply at some point? I have no idea who is maintaining this file.

Regards,
Axel

 drivers/gpio/spear_gpio.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

drivers/gpio/spear_gpio.c +0 -0

index 367b670..6fb4117 100644
@@ -36,7 +36,10 @@ int gpio_set_value(unsigned gpio, int value)
 {

drivers/gpio/spear_gpio.c int gpio_set_value(unsigned gpio, int value) · line 45

Quoted 10 lines

drivers/gpio/spear_gpio.c +4 -1

      struct gpio_regs *regs = (struct gpio_regs *)CONFIG_GPIO_BASE;
 
-     writel(1 << gpio, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
+     if (value)
+             writel(1 << gpio, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
+     else
+             writel(0, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
 
      return 0;
 }

Despite discussions in the previous thread and the confirmations that this code is functionally equivalent to the Linux code, I still believe this code is incorrect for both writing and reading.

From the doc, writing to GPIODATA will obviously copy each of bits 7 to 0 of the written value into the actuals GPIO mapped to bits 7 to 0 of this register (assuming they are configured as outputs, of course). Based on this, the code above:

- when setting a single GPIO, sets *but clears up to seven other GPIOs*;
- when clearing a single GPIO, clears it *and up to seven other GPIOs*.

This code may have been tested only for a single active GPIO at a time, for which this code would behave correctly; but as soon as two GPIOs from the same bank must be set at the same time, it fails.

Please fix this code so that setting or clearing a GPIO does not set or clear any other GPIO, and perform an actual test to confirm this works before submitting V2.

BTW: if (as the previous thread seemed to imply) no one around has the hardware to test this change, then why exactly is it needed?

Amicalement,
--
Albert.

Hi Axel,

Quoted 37 lines · Axel Lin

In current gpio_set_value() implementation, it always sets the gpio control bit no matter the value argument is 0 or 1. Thus the GPIOs never set to low. This patch fixes this bug.

Signed-off-by Axel Lin <[email protected]>

Acked-by Stefan Roese <[email protected]>

Reviewed-by Vipin Kumar <[email protected]>

---
This patch was sent on http://lists.denx.de/pipermail/u-boot/2013-June/156861.html

Has Stefan's Ack:
http://lists.denx.de/pipermail/u-boot/2013-June/156864.html

Vipin says the code is fine, so I add Vipin's review-by.
http://lists.denx.de/pipermail/u-boot/2013-June/156966.html

Michael confirms it works:
http://lists.denx.de/pipermail/u-boot/2013-August/160652.html

No body picks up this patch, so here is a resend.
Although I think this is a bug fix, but I'll let maintainers to determinate if this is the material for v2013.10.
Anyway, can someone at least let me know if this patch is ok for apply at some point? I have no idea who is maintaining this file.

Regards,
Axel

 drivers/gpio/spear_gpio.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

drivers/gpio/spear_gpio.c +0 -0

index 367b670..6fb4117 100644
@@ -36,7 +36,10 @@ int gpio_set_value(unsigned gpio, int value)
 {

drivers/gpio/spear_gpio.c int gpio_set_value(unsigned gpio, int value) · line 45

Quoted 10 lines

drivers/gpio/spear_gpio.c +4 -1

      struct gpio_regs *regs = (struct gpio_regs *)CONFIG_GPIO_BASE;
 
-     writel(1 << gpio, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
+     if (value)
+             writel(1 << gpio, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
+     else
+             writel(0, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
 
      return 0;
 }

Despite discussions in the previous thread and the confirmations that this code is functionally equivalent to the Linux code, I still believe this code is incorrect for both writing and reading.

From the doc, writing to GPIODATA will obviously copy each of bits 7 to 0 of the written value into the actuals GPIO mapped to bits 7 to 0 of this register (assuming they are configured as outputs, of course). Based on this, the code above:

- when setting a single GPIO, sets *but clears up to seven other GPIOs*;
- when clearing a single GPIO, clears it *and up to seven other GPIOs*.

This code may have been tested only for a single active GPIO at a time, for which this code would behave correctly; but as soon as two GPIOs from the same bank must be set at the same time, it fails.

Please fix this code so that setting or clearing a GPIO does not set or clear any other GPIO, and perform an actual test to confirm this works before submitting V2.

BTW: if (as the previous thread seemed to imply) no one around has the hardware to test this change, then why exactly is it needed?

Amicalement,
--
Albert.

2013/9/14 Albert ARIBAUD <[email protected]>:

Quoted 65 lines

Hi Axel,

Quoted 37 lines · Axel Lin

In current gpio_set_value() implementation, it always sets the gpio control bit no matter the value argument is 0 or 1. Thus the GPIOs never set to low. This patch fixes this bug.

Signed-off-by Axel Lin <[email protected]>

Acked-by Stefan Roese <[email protected]>

Reviewed-by Vipin Kumar <[email protected]>

---
This patch was sent on http://lists.denx.de/pipermail/u-boot/2013-June/156861.html

Has Stefan's Ack:
http://lists.denx.de/pipermail/u-boot/2013-June/156864.html

Vipin says the code is fine, so I add Vipin's review-by.
http://lists.denx.de/pipermail/u-boot/2013-June/156966.html

Michael confirms it works:
http://lists.denx.de/pipermail/u-boot/2013-August/160652.html

No body picks up this patch, so here is a resend.
Although I think this is a bug fix, but I'll let maintainers to determinate if this is the material for v2013.10.
Anyway, can someone at least let me know if this patch is ok for apply at some point? I have no idea who is maintaining this file.

Regards,
Axel

 drivers/gpio/spear_gpio.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

drivers/gpio/spear_gpio.c +0 -0

index 367b670..6fb4117 100644
@@ -36,7 +36,10 @@ int gpio_set_value(unsigned gpio, int value)
 {

drivers/gpio/spear_gpio.c int gpio_set_value(unsigned gpio, int value) · line 45

Quoted 10 lines

drivers/gpio/spear_gpio.c +4 -1

      struct gpio_regs *regs = (struct gpio_regs *)CONFIG_GPIO_BASE;
 
-     writel(1 << gpio, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
+     if (value)
+             writel(1 << gpio, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
+     else
+             writel(0, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
 
      return 0;
 }

Despite discussions in the previous thread and the confirmations that this code is functionally equivalent to the Linux code, I still believe this code is incorrect for both writing and reading.

From the doc, writing to GPIODATA will obviously copy each of bits 7 to 0 of the written value into the actuals GPIO mapped to bits 7 to 0 of this register (assuming they are configured as outputs, of course). Based on this, the code above:

- when setting a single GPIO, sets *but clears up to seven other GPIOs*;
- when clearing a single GPIO, clears it *and up to seven other GPIOs*.

Quoted 7 lines

This code may have been tested only for a single active GPIO at a time, for which this code would behave correctly; but as soon as two GPIOs from the same bank must be set at the same time, it fails.

Please fix this code so that setting or clearing a GPIO does not set or clear any other GPIO, and perform an actual test to confirm this works before submitting V2.

No.
Some people (Marek, and *Michael*) asked this question in original discussion thread.
The datasheet says each GPIO is controlled by *different* register. (Well, it's unusual.)
And that is why we don't need a read-write-update operation. Simply write 0 to the register does work. ( *Michael* replied it works )

Quoted 4 lines

BTW: if (as the previous thread seemed to imply) no one around has the hardware to test this change, then why exactly is it needed?

Quoted 3 lines

Amicalement,
--
Albert.

Hi Axel

Quoted 83 lines · Axel Lin

2013/9/14 Albert ARIBAUD <[email protected]>:

Quoted 65 lines

Hi Axel,

Quoted 37 lines · Axel Lin

In current gpio_set_value() implementation, it always sets the gpio control bit no matter the value argument is 0 or 1. Thus the GPIOs never set to low. This patch fixes this bug.

Signed-off-by Axel Lin <[email protected]>

Acked-by Stefan Roese <[email protected]>

Reviewed-by Vipin Kumar <[email protected]>

---
This patch was sent on http://lists.denx.de/pipermail/u-boot/2013-June/156861.html

Has Stefan's Ack:
http://lists.denx.de/pipermail/u-boot/2013-June/156864.html

Vipin says the code is fine, so I add Vipin's review-by.
http://lists.denx.de/pipermail/u-boot/2013-June/156966.html

Michael confirms it works:
http://lists.denx.de/pipermail/u-boot/2013-August/160652.html

No body picks up this patch, so here is a resend.
Although I think this is a bug fix, but I'll let maintainers to determinate if this is the material for v2013.10.
Anyway, can someone at least let me know if this patch is ok for apply at some point? I have no idea who is maintaining this file.

Regards,
Axel

 drivers/gpio/spear_gpio.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

drivers/gpio/spear_gpio.c +0 -0

index 367b670..6fb4117 100644
@@ -36,7 +36,10 @@ int gpio_set_value(unsigned gpio, int value)
 {

drivers/gpio/spear_gpio.c int gpio_set_value(unsigned gpio, int value) · line 45

Quoted 10 lines

drivers/gpio/spear_gpio.c +4 -1

      struct gpio_regs *regs = (struct gpio_regs *)CONFIG_GPIO_BASE;
 
-     writel(1 << gpio, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
+     if (value)
+             writel(1 << gpio, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
+     else
+             writel(0, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
 
      return 0;
 }

Despite discussions in the previous thread and the confirmations that this code is functionally equivalent to the Linux code, I still believe this code is incorrect for both writing and reading.

From the doc, writing to GPIODATA will obviously copy each of bits 7 to 0 of the written value into the actuals GPIO mapped to bits 7 to 0 of this register (assuming they are configured as outputs, of course). Based on this, the code above:

- when setting a single GPIO, sets *but clears up to seven other GPIOs*;
- when clearing a single GPIO, clears it *and up to seven other GPIOs*.

Quoted 7 lines

This code may have been tested only for a single active GPIO at a time, for which this code would behave correctly; but as soon as two GPIOs from the same bank must be set at the same time, it fails.

Please fix this code so that setting or clearing a GPIO does not set or clear any other GPIO, and perform an actual test to confirm this works before submitting V2.

No.
Some people (Marek, and *Michael*) asked this question in original discussion thread.
The datasheet says each GPIO is controlled by *different* register. (Well, it's unusual.)
And that is why we don't need a read-write-update operation. Simply write 0 to the register does work. ( *Michael* replied it works )

Quoted 1 line

Quoted 3 lines

Quoted 3 lines

BTW: if (as the previous thread seemed to imply) no one around has the hardware to test this change, then why exactly is it needed?

Yes it's a strange implementation but looking at the documentation seems correct

Michael

Hi Michael,

Quoted 90 lines · Michael Trimarchi

Hi Axel

Quoted 86 lines · Axel Lin

2013/9/14 Albert ARIBAUD <[email protected]>:

Quoted 65 lines

Hi Axel,

Quoted 37 lines · Axel Lin

In current gpio_set_value() implementation, it always sets the gpio control bit no matter the value argument is 0 or 1. Thus the GPIOs never set to low. This patch fixes this bug.

Signed-off-by Axel Lin <[email protected]>

Acked-by Stefan Roese <[email protected]>

Reviewed-by Vipin Kumar <[email protected]>

---
This patch was sent on http://lists.denx.de/pipermail/u-boot/2013-June/156861.html

Has Stefan's Ack:
http://lists.denx.de/pipermail/u-boot/2013-June/156864.html

Vipin says the code is fine, so I add Vipin's review-by.
http://lists.denx.de/pipermail/u-boot/2013-June/156966.html

Michael confirms it works:
http://lists.denx.de/pipermail/u-boot/2013-August/160652.html

No body picks up this patch, so here is a resend.
Although I think this is a bug fix, but I'll let maintainers to determinate if this is the material for v2013.10.
Anyway, can someone at least let me know if this patch is ok for apply at some point? I have no idea who is maintaining this file.

Regards,
Axel

 drivers/gpio/spear_gpio.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

drivers/gpio/spear_gpio.c +0 -0

index 367b670..6fb4117 100644
@@ -36,7 +36,10 @@ int gpio_set_value(unsigned gpio, int value)
 {

drivers/gpio/spear_gpio.c int gpio_set_value(unsigned gpio, int value) · line 45

Quoted 10 lines

drivers/gpio/spear_gpio.c +4 -1

      struct gpio_regs *regs = (struct gpio_regs *)CONFIG_GPIO_BASE;
 
-     writel(1 << gpio, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
+     if (value)
+             writel(1 << gpio, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
+     else
+             writel(0, &regs->gpiodata[DATA_REG_ADDR(gpio)]);
 
      return 0;
 }

Despite discussions in the previous thread and the confirmations that this code is functionally equivalent to the Linux code, I still believe this code is incorrect for both writing and reading.

From the doc, writing to GPIODATA will obviously copy each of bits 7 to 0 of the written value into the actuals GPIO mapped to bits 7 to 0 of this register (assuming they are configured as outputs, of course). Based on this, the code above:

- when setting a single GPIO, sets *but clears up to seven other GPIOs*;
- when clearing a single GPIO, clears it *and up to seven other GPIOs*.

Quoted 7 lines

This code may have been tested only for a single active GPIO at a time, for which this code would behave correctly; but as soon as two GPIOs from the same bank must be set at the same time, it fails.

Please fix this code so that setting or clearing a GPIO does not set or clear any other GPIO, and perform an actual test to confirm this works before submitting V2.

No.
Some people (Marek, and *Michael*) asked this question in original discussion thread.
The datasheet says each GPIO is controlled by *different* register. (Well, it's unusual.)
And that is why we don't need a read-write-update operation. Simply write 0 to the register does work. ( *Michael* replied it works )

Quoted 4 lines

BTW: if (as the previous thread seemed to imply) no one around has the hardware to test this change, then why exactly is it needed?

Quoted 1 line

Yes it's a strange implementation but looking at the documentation seems correct

Ok-- I got the "masking address" trick this time, thanks. It is indeed unusual, and the code is indeed correct. However, I would like the patch to include a few lines of comment to explain how and why it works, for the benefit of its future readers who might find it weird too.

Quoted 1 line

Michael

Amicalement,
--
Albert.