[PATCH] ARM: OMAP2+: ads7846 init: fix fault caused by freeing pen-down GPIO

Igor Grinberg [off-list ref] writes:

On 07/27/12 20:46, Kevin Hilman wrote:

quoted

Igor Grinberg [off-list ref] writes:

quoted

On 07/26/12 22:30, Kevin Hilman wrote:

quoted

+ Zumeng Chen

Igor Grinberg [off-list ref] writes:

quoted

Hi Kevin,

I've just noticed that the patch has been modified by Arnd in a way
that of course will trigger GPIO use without being requested.
I'm sorry, I was not available by that time Arnd changed the patch.

Your right, your original patch isn't the problem.  I found the root
cause.

The real problem is actually introduced by the merge of your patch from
the arm-soc/cleanup branch, and this one from Zumeng Chen: commit
16aced80f6 (ARM: OMAP3530evm: set pendown_state and debounce time for
ads7846) from the arm-soc/boards branch.

However, looking closer at the one from Zumeng, that one is clearly not
right.  It unconditionally adds a *board-specific* ->get_pendown_state
function to the pdata that is common to *all* boards.  That's just wrong
and has the side-effect of making ->get_pendown_state() wrong on every
board except the OMAP3EVM.  Oops.

Argh... that should not be applied in first place...

Agreed, but it's already in mainline.

quoted

I double sorry, I was not available when that conflict was resolved...
The right resolution would be just to revert the 16aced80f6
(ARM: OMAP3530evm: set pendown_state and debounce time for ads7846),
but who cares now...

quoted

quoted

So, IMO, in addition to $SUBJECT patch, in order to get the touchscreen
GPIO working on non OMAP3EVM boards, we also need something like this as
well.

Igor, Zumeng, could you try this out on your boards anc confirm if it's
working?  I currently don't have a board setup with a touchscreen in my
board farm.

Since you have already dig into this, which branch would be good for testing?

git://git.kernel.org/pub/scm/linux/kernel/git/khilman/linux-omap-pm.git for_3.6/fixes/ads7846

I just pushed this out, so it might take a bit to propagate to all the
mirrors.

Thanks, Kevin, I've just sent the tested-by.
I would also like to see only one patch instead of current two patches,
can you please, amend them into one, write a correct message and resend?

Yeah, the changelog in my first patch isn't quite right anymore since
your patch isn't the one that caused the problems.

You're more familiar with this code than me, so feel free to recombine
them if you like, and I'll queue it up for v3.6-rc.

Thanks,

Kevin

1) The above commit introduced a common ->get_pendown_state() function
into the generic code, but that function was board-specific for the
OMAP3EVM and thus broke most other boards using this code.

2) The above commit was mis-merged introducing another bug which
prevents the ads7846 driver probe function to succeed.
The omap_ads7846_init() function frees the pendown GPIO in case there is
no ->get_pendown_state() function set by the caller (board specific
code), so it can be requested later by the ads7846 driver.
The above commit add a common ->get_pendown_state() function without
removing the gpio_free() call and thus once the ads7846 driver tries
to use the pendown GPIO, it crashes as the pendown GPIO has not been
requested.

3) The above commit introduces NO new functionality as
get_pendown_state() function is already implemented in a suitable way by
the ads7846 driver and the debounce time handling has already been
fixed by commit 97ee9f01 (ARM: OMAP: fix the ads7846 init code).

This reverts commit 16aced80f6739beb2a6ff7b6f96c83ba80d331e8.

Conflicts:
	arch/arm/mach-omap2/common-board-devices.c

Solved by taking the working version prior to the above commit.

Cc: Zumeng Chen <redacted>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Igor Grinberg <redacted>
---
Kevin, sorry for the late reply.
How about the above commit message and the below patch?

The patch applies cleanly to Tony's master branch (6 Aug 2012)
or Kevin's kevin-omap-pm/for_3.6/fixes/ads7846
after resetting two top most commits.

This patch has been tested on both above branches on cm-t3730.
Any other board tested will be greately appreciated.

Also, if after all said in the commit message, you still don't
want to revert the original patch, feel free to post your thoughts.

 arch/arm/mach-omap2/board-omap3evm.c       |    1 +
 arch/arm/mach-omap2/common-board-devices.c |   11 -----------
 arch/arm/mach-omap2/common-board-devices.h |    1 -
 3 files changed, 1 insertions(+), 12 deletions(-)

diff --git a/arch/arm/mach-omap2/board-omap3evm.c b/arch/arm/mach-omap2/board-omap3evm.c
index ef230a0..0d362e9 100644
--- a/arch/arm/mach-omap2/board-omap3evm.c
+++ b/arch/arm/mach-omap2/board-omap3evm.c

@@ -58,6 +58,7 @@
 #include "hsmmc.h"
 #include "common-board-devices.h"
 
+#define OMAP3_EVM_TS_GPIO	175
 #define OMAP3_EVM_EHCI_VBUS	22
 #define OMAP3_EVM_EHCI_SELECT	61
 

diff --git a/arch/arm/mach-omap2/common-board-devices.c b/arch/arm/mach-omap2/common-board-devices.c
index 1473474..c187586 100644
--- a/arch/arm/mach-omap2/common-board-devices.c
+++ b/arch/arm/mach-omap2/common-board-devices.c

@@ -35,16 +35,6 @@ static struct omap2_mcspi_device_config ads7846_mcspi_config = {
 	.turbo_mode	= 0,
 };
 
-/*
- * ADS7846 driver maybe request a gpio according to the value
- * of pdata->get_pendown_state, but we have done this. So set
- * get_pendown_state to avoid twice gpio requesting.
- */
-static int omap3_get_pendown_state(void)
-{
-	return !gpio_get_value(OMAP3_EVM_TS_GPIO);
-}
-
 static struct ads7846_platform_data ads7846_config = {
 	.x_max			= 0x0fff,
 	.y_max			= 0x0fff,

@@ -55,7 +45,6 @@ static struct ads7846_platform_data ads7846_config = {
 	.debounce_rep		= 1,
 	.gpio_pendown		= -EINVAL,
 	.keep_vref_on		= 1,
-	.get_pendown_state	= &omap3_get_pendown_state,
 };
 
 static struct spi_board_info ads7846_spi_board_info __initdata = {

diff --git a/arch/arm/mach-omap2/common-board-devices.h b/arch/arm/mach-omap2/common-board-devices.h
index 4c4ef6a..a0b4a428 100644
--- a/arch/arm/mach-omap2/common-board-devices.h
+++ b/arch/arm/mach-omap2/common-board-devices.h

@@ -4,7 +4,6 @@
 #include "twl-common.h"
 
 #define NAND_BLOCK_SIZE	SZ_128K
-#define OMAP3_EVM_TS_GPIO	175
 
 struct mtd_partition;
 struct ads7846_platform_data;

-- 
1.7.3.4

? 2012?08?07? 04:22, Igor Grinberg ??:

1) The above commit introduced a common ->get_pendown_state() function
into the generic code, but that function was board-specific for the
OMAP3EVM and thus broke most other boards using this code.

2) The above commit was mis-merged introducing another bug which
prevents the ads7846 driver probe function to succeed.
The omap_ads7846_init() function frees the pendown GPIO in case there is
no ->get_pendown_state() function set by the caller (board specific
code), so it can be requested later by the ads7846 driver.
The above commit add a common ->get_pendown_state() function without
removing the gpio_free() call and thus once the ads7846 driver tries
to use the pendown GPIO, it crashes as the pendown GPIO has not been
requested.

3) The above commit introduces NO new functionality as
get_pendown_state() function is already implemented in a suitable way by
the ads7846 driver and the debounce time handling has already been
fixed by commit 97ee9f01 (ARM: OMAP: fix the ads7846 init code).

Igor,

I suspect these two patches(this and 97ee9f01) works well, and there
is something new introduced in ads7846.c, I'll try to look at that new
stuff in this weekend.

Please refer to in-line comments:

Regards,
Zumeng

You remove this, then please look at the following codes:

drivers/input/touchscreen/ads7846.c

969 if (pdata->get_pendown_state) {
970 ts->get_pendown_state = pdata->get_pendown_state;
971 } else if (gpio_is_valid(pdata->gpio_pendown)) {
972
973 err = gpio_request_one(pdata->gpio_pendown, GPIOF_IN,
^^^, the driver will want to request again, then it should
be error if i'm right.

974 "ads7846_pendown");
975 if (err) {
976 dev_err(&spi->dev,
977 "failed to request/setup pendown GPIO%d: %d\n",
978 pdata->gpio_pendown, err);
979 return err;
980 }
981
982 ts->gpio_pendown = pdata->gpio_pendown;
983
984 } else {

Regards,
Zumeng

On 08/07/12 04:42, Zumeng Chen wrote:

? 2012?08?07? 04:22, Igor Grinberg ??:

quoted

1) The above commit introduced a common ->get_pendown_state() function
into the generic code, but that function was board-specific for the
OMAP3EVM and thus broke most other boards using this code.

2) The above commit was mis-merged introducing another bug which
prevents the ads7846 driver probe function to succeed.
The omap_ads7846_init() function frees the pendown GPIO in case there is
no ->get_pendown_state() function set by the caller (board specific
code), so it can be requested later by the ads7846 driver.
The above commit add a common ->get_pendown_state() function without
removing the gpio_free() call and thus once the ads7846 driver tries
to use the pendown GPIO, it crashes as the pendown GPIO has not been
requested.

3) The above commit introduces NO new functionality as
get_pendown_state() function is already implemented in a suitable way by
the ads7846 driver and the debounce time handling has already been
fixed by commit 97ee9f01 (ARM: OMAP: fix the ads7846 init code).

Igor,

I suspect these two patches(this and 97ee9f01) works well, and there
is something new introduced in ads7846.c, I'll try to look at that new
stuff in this weekend.

Please refer to in-line comments:

Regards,
Zumeng

quoted

This reverts commit 16aced80f6739beb2a6ff7b6f96c83ba80d331e8.

Conflicts:
	arch/arm/mach-omap2/common-board-devices.c

Solved by taking the working version prior to the above commit.

Cc: Zumeng Chen <redacted>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Igor Grinberg <redacted>
---
Kevin, sorry for the late reply.
How about the above commit message and the below patch?

The patch applies cleanly to Tony's master branch (6 Aug 2012)
or Kevin's kevin-omap-pm/for_3.6/fixes/ads7846
after resetting two top most commits.

This patch has been tested on both above branches on cm-t3730.
Any other board tested will be greately appreciated.

Also, if after all said in the commit message, you still don't
want to revert the original patch, feel free to post your thoughts.

 arch/arm/mach-omap2/board-omap3evm.c       |    1 +
 arch/arm/mach-omap2/common-board-devices.c |   11 -----------
 arch/arm/mach-omap2/common-board-devices.h |    1 -
 3 files changed, 1 insertions(+), 12 deletions(-)

diff --git a/arch/arm/mach-omap2/board-omap3evm.c b/arch/arm/mach-omap2/board-omap3evm.c
index ef230a0..0d362e9 100644
--- a/arch/arm/mach-omap2/board-omap3evm.c
+++ b/arch/arm/mach-omap2/board-omap3evm.c

@@ -58,6 +58,7 @@
 #include "hsmmc.h"
 #include "common-board-devices.h"
 
+#define OMAP3_EVM_TS_GPIO	175
 #define OMAP3_EVM_EHCI_VBUS	22
 #define OMAP3_EVM_EHCI_SELECT	61
 

diff --git a/arch/arm/mach-omap2/common-board-devices.c b/arch/arm/mach-omap2/common-board-devices.c
index 1473474..c187586 100644
--- a/arch/arm/mach-omap2/common-board-devices.c
+++ b/arch/arm/mach-omap2/common-board-devices.c

@@ -35,16 +35,6 @@ static struct omap2_mcspi_device_config ads7846_mcspi_config = {
 	.turbo_mode	= 0,
 };
 
-/*
- * ADS7846 driver maybe request a gpio according to the value
- * of pdata->get_pendown_state, but we have done this. So set
- * get_pendown_state to avoid twice gpio requesting.
- */
-static int omap3_get_pendown_state(void)
-{
-	return !gpio_get_value(OMAP3_EVM_TS_GPIO);
-}
-
 static struct ads7846_platform_data ads7846_config = {
 	.x_max			= 0x0fff,
 	.y_max			= 0x0fff,

@@ -55,7 +45,6 @@ static struct ads7846_platform_data ads7846_config = {
 	.debounce_rep		= 1,
 	.gpio_pendown		= -EINVAL,
 	.keep_vref_on		= 1,
-	.get_pendown_state	= &omap3_get_pendown_state,

You remove this, then please look at the following codes:

drivers/input/touchscreen/ads7846.c

969 if (pdata->get_pendown_state) {
970 ts->get_pendown_state = pdata->get_pendown_state;
971 } else if (gpio_is_valid(pdata->gpio_pendown)) {
972
973 err = gpio_request_one(pdata->gpio_pendown, GPIOF_IN,
^^^, the driver will want to request again, then it should
be error if i'm right.

This patch removes the get_pendown_state function pointer from
the ads7846_platform_data and gpio_free() fires as there is no
get_pendown_state and therefore there will be no problem to request
it again by the ads7846 driver.
So, no there will be no error and if you still doubt, please test.

974 "ads7846_pendown");
975 if (err) {
976 dev_err(&spi->dev,
977 "failed to request/setup pendown GPIO%d: %d\n",
978 pdata->gpio_pendown, err);
979 return err;
980 }
981
982 ts->gpio_pendown = pdata->gpio_pendown;
983
984 } else {

[...]


-- 
Regards,
Igor.