spi: Add the flag indicate to registe new device as children of master or not.

PATCH In review Jun Chen 3 participants 9 messages Dec 18, 2012 – Jan 11, 2013 SPI

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Jun Chen

author

2012-12-18 08:26 UTC #0 lore raw

PATCH 1/1 spi: Add the flag indicate to registe new device as children of master or not.

Because there are two aim when allocating the new device, one is for children of master, other is for master. So this patch add one flag to indicate different purpose.

Signed-off-by Bi Chao <[email protected]>

Signed-off-by Chen Jun <[email protected]>

---
 drivers/spi/spi.c       |   16 +++++++++++-----
 include/linux/spi/spi.h |    3 ++-
 2 files changed, 13 insertions(+), 6 deletions(-)

drivers/spi/spi.c +11 -5

index 718cc1f..06f69ce 100644
@@ -300,6 +300,8 @@ static DEFINE_MUTEX(board_lock);
 /**
  * spi_alloc_device - Allocate a new SPI device
  * @master: Controller to which device is connected
+ * device_was_children_of_master is flag which the device is registed
+ * as the children of the bus
  * Context: can sleep
  *
  * Allows a driver to allocate and initialize a spi_device without

@@ -314,7 +316,8 @@ static DEFINE_MUTEX(board_lock);
  *
  * Returns a pointer to the new device, or NULL.
  */
-struct spi_device *spi_alloc_device(struct spi_master *master)
+struct spi_device *spi_alloc_device(struct spi_master *master,
+				bool device_was_children_of_master)
 {
 	struct spi_device	*spi;
 	struct device		*dev = master->dev.parent;

@@ -330,7 +333,10 @@ struct spi_device *spi_alloc_device(struct spi_master *master)
 	}
 
 	spi->master = master;
-	spi->dev.parent = &master->dev;
+	if (device_was_children_of_master == true)
+		spi->dev.parent = &master->dev;
+	else
+		spi->dev.parent = dev;
 	spi->dev.bus = &spi_bus_type;
 	spi->dev.release = spidev_release;
 	device_initialize(&spi->dev);

@@ -434,7 +440,7 @@ struct spi_device *spi_new_device(struct spi_master *master,
 	 * suggests syslogged diagnostics are best here (ugh).
 	 */
 
-	proxy = spi_alloc_device(master);
+	proxy = spi_alloc_device(master, false);
 	if (!proxy)
 		return NULL;

@@ -827,7 +833,7 @@ static void of_register_spi_devices(struct spi_master *master)
 
 	for_each_available_child_of_node(master->dev.of_node, nc) {
 		/* Alloc an spi_device */
-		spi = spi_alloc_device(master);
+		spi = spi_alloc_device(master, true);
 		if (!spi) {
 			dev_err(&master->dev, "spi_device alloc error for %s\n",
 				nc->full_name);

@@ -939,7 +945,7 @@ static acpi_status acpi_spi_add_device(acpi_handle handle, u32 level,
 	if (acpi_bus_get_status(adev) || !adev->status.present)
 		return AE_OK;
 
-	spi = spi_alloc_device(master);
+	spi = spi_alloc_device(master, false);
 	if (!spi) {
 		dev_err(&master->dev, "failed to allocate SPI device for %s\n",
 			dev_name(&adev->dev));

include/linux/spi/spi.h +2 -1

index fa702ae..43d2f8e 100644
@@ -838,7 +838,8 @@ spi_register_board_info(struct spi_board_info const *info, unsigned n)
  * be defined using the board info.
  */
 extern struct spi_device *
-spi_alloc_device(struct spi_master *master);
+spi_alloc_device(struct spi_master *master,
+				bool device_was_children_of_master);
 
 extern int
 spi_add_device(struct spi_device *spi);

Signature · 1 line

1.7.4.1

Mark Brown

2012-12-18 15:26 UTC #1 lore raw

Quoted 3 lines · Jun Chen

* @master: Controller to which device is connected
+ * device_was_children_of_master is flag which the device is registed
+ * as the children of the bus

This isn't a kerneldoc style comment (it needs the @XXX: format). The name is also extremely long, can't we think of something more concise?

drivers/spi/spi.c struct spi_device *spi_alloc_device(struct spi_master *master) · line 339

Quoted 5 lines

drivers/spi/spi.c +4 -1

-	spi->dev.parent = &master->dev;
+	if (device_was_children_of_master == true)
+		spi->dev.parent = &master->dev;
+	else
+		spi->dev.parent = dev;

Can you provide an example of where this is useful? Your changelog didn't make it clear and the code doesn't make it obvious either.

Jun Chen

author

2012-12-19 01:41 UTC #2 lore raw

Quoted 9 lines · Mark Brown

Quoted 3 lines · Jun Chen
* @master: Controller to which device is connected
+ * device_was_children_of_master is flag which the device is registed
+ * as the children of the bus
This isn't a kerneldoc style comment (it needs the @XXX: format). The name is also extremely long, can't we think of something more concise?

Thank for your suggestion, I will correct this comment and use concise flag.

Quoted 8 lines

drivers/spi/spi.c struct spi_device *spi_alloc_device(struct spi_master *master) · line 339
Quoted 5 lines
drivers/spi/spi.c +4 -1
-	spi->dev.parent = &master->dev;
+	if (device_was_children_of_master == true)
+		spi->dev.parent = &master->dev;
+	else
+		spi->dev.parent = dev;
Can you provide an example of where this is useful? Your changelog didn't make it clear and the code doesn't make it obvious either.

This spi_alloc_device function will be called in the spi_new_device function to alloc new device as the master. But other way, it is called by the of_register_spi_devices function to register new device as the children of the master. I will update changlog to add it.

@@ -434,7 +440,7 @@ struct spi_device *spi_new_device(struct spi_master *master,
* suggests syslogged diagnostics are best here (ugh). */

- proxy = spi_alloc_device(master);

+       proxy = spi_alloc_device(master, false);
        if (!proxy)
                return NULL;

@@ -827,7 +833,7 @@ static void of_register_spi_devices(struct spi_master *master)

        for_each_available_child_of_node(master->dev.of_node, nc) {
                /* Alloc an spi_device */

- spi = spi_alloc_device(master);
+ spi = spi_alloc_device(master, true);

If I have mistake, pls correct me, thanks!

Mark Brown

2012-12-19 09:04 UTC #3 lore raw

Quoted 4 lines · Jun Chen

This spi_alloc_device function will be called in the spi_new_device function to alloc new device as the master. But other way, it is called by the of_register_spi_devices function to register new device as the children of the master. I will update changlog to add it.

But why is this a bad thing? You've said what's happening but not why it's a problem.

Grant Likely

2012-12-19 16:21 UTC #4 lore raw

Quoted 9 lines · Mark Brown

Quoted 4 lines · Jun Chen
This spi_alloc_device function will be called in the spi_new_device function to alloc new device as the master. But other way, it is called by the of_register_spi_devices function to register new device as the children of the master. I will update changlog to add it.
But why is this a bad thing? You've said what's happening but not why it's a problem.

spi_devices should always be children of the spi_master. If that is not the case then it is a bug to be fixed.

Signature · 9 lines

Grant Likely, B.Sc, P.Eng.
Secret Lab Technologies, Ltd.

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Jun Chen

author

2012-12-21 09:38 UTC #5 lore raw

Quoted 8 lines · Grant Likely

Quoted 7 lines · Mark Brown
Quoted 4 lines · Jun Chen
This spi_alloc_device function will be called in the spi_new_device function to alloc new device as the master. But other way, it is called by the of_register_spi_devices function to register new device as the children of the master. I will update changlog to add it.

Quoted 6 lines

Quoted 2 lines
But why is this a bad thing? You've said what's happening but not why it's a problem.
spi_devices should always be children of the spi_master. If that is not the case then it is a bug to be fixed.

When many boards initializing, boards will call function spi_register_board_info to create bi->board_info,Then spi driver probe to call spi_register_master to register the driver and in the function spi_match_master_to_boardinfo To create new spi device, and this cases the spi_devices are not children of the spi_master.
Many drivers do these steps. If all spi_devices must be children of the spi_master, Do spi core have plan to delete this way?
Or spi core can hold this way for many drivers.
Thanks!

Grant Likely

2012-12-21 19:06 UTC #6 lore raw

Quoted 16 lines · Jun Chen

Quoted 8 lines · Grant Likely
Quoted 7 lines · Mark Brown
Quoted 4 lines · Jun Chen
This spi_alloc_device function will be called in the spi_new_device function to alloc new device as the master. But other way, it is called by the of_register_spi_devices function to register new device as the children of the master. I will update changlog to add it.
Quoted 6 lines
Quoted 2 lines
But why is this a bad thing? You've said what's happening but not why it's a problem.
spi_devices should always be children of the spi_master. If that is not the case then it is a bug to be fixed.

Quoted 8 lines

When many boards initializing, boards will call function spi_register_board_info to create bi->board_info,Then spi driver probe to call spi_register_master to register the driver and in the function spi_match_master_to_boardinfo To create new spi device, and this cases the spi_devices are not children of the spi_master.
Many drivers do these steps. If all spi_devices must be children of the spi_master, Do spi core have plan to delete this way?
Or spi core can hold this way for many drivers.

Let me make sure I understand what you're saying...

Right now, every spi_device object is registered as a child of an spi_master object.

With this proposed patch, spi_devices registered via spi_register_board_info will be siblings of the spi_master instead of children.

Do I understand correctly so far?

The problem is that I don't understand why this change is necessary. spi_devices should always be children of an spi_master, not siblings. What is the problem you're trying to solve with this change?

Jun Chen

author

2012-12-24 08:15 UTC #7 lore raw

Quoted 28 lines · Grant Likely

Quoted 16 lines · Jun Chen
Quoted 8 lines · Grant Likely
Quoted 7 lines · Mark Brown
Quoted 4 lines · Jun Chen
This spi_alloc_device function will be called in the spi_new_device function to alloc new device as the master. But other way, it is called by the of_register_spi_devices function to register new device as the children of the master. I will update changlog to add it.
Quoted 6 lines
Quoted 2 lines
But why is this a bad thing? You've said what's happening but not why it's a problem.
spi_devices should always be children of the spi_master. If that is not the case then it is a bug to be fixed.
Quoted 8 lines
When many boards initializing, boards will call function spi_register_board_info to create bi->board_info,Then spi driver probe to call spi_register_master to register the driver and in the function spi_match_master_to_boardinfo To create new spi device, and this cases the spi_devices are not children of the spi_master.
Many drivers do these steps. If all spi_devices must be children of the spi_master, Do spi core have plan to delete this way?
Or spi core can hold this way for many drivers.
Let me make sure I understand what you're saying...

Quoted 8 lines

Right now, every spi_device object is registered as a child of an spi_master object.
With this proposed patch, spi_devices registered via spi_register_board_info will be siblings of the spi_master instead of children.
Do I understand correctly so far?

Yes,

Quoted 4 lines

The problem is that I don't understand why this change is necessary. spi_devices should always be children of an spi_master, not siblings. What is the problem you're trying to solve with this change?

When spi drivers try to use the core function(spi_register_master),it will trigger error,because they use the function spi_match_master_to_boardinfo to create new spi device as the children of the master.
In the old version of spi core, the new devices are registered as siblings of the spi_master. My spi driver based on the old version runs normal.

But after applying for this patch:
{
spi: Fix device unregistration when unregistering the bus master

Device are added as children of the bus master's parent device, but spi_unregister_master() looks for devices to unregister in the bus master's children. This results in the child devices not being unregistered.

Fix this by registering devices as direct children of the bus
master.

- spi->dev.parent = dev;
+ spi->dev.parent = &master->dev;
}

Then my driver will be crash.
Maybe I have mistake on this issue, thank for your more explanation and detail replay.

Quoted 2 lines

g.

Grant Likely

2013-01-11 14:57 UTC #8 lore raw

Quoted 30 lines · Jun Chen

Quoted 4 lines · Grant Likely
The problem is that I don't understand why this change is necessary. spi_devices should always be children of an spi_master, not siblings. What is the problem you're trying to solve with this change?
When spi drivers try to use the core function(spi_register_master),it will trigger error,because they use the function spi_match_master_to_boardinfo to create new spi device as the children of the master.
In the old version of spi core, the new devices are registered as siblings of the spi_master. My spi driver based on the old version runs normal.
But after applying for this patch:
{
spi: Fix device unregistration when unregistering the bus master
Device are added as children of the bus master's parent device, but spi_unregister_master() looks for devices to unregister in the bus master's children. This results in the child devices not being unregistered.
Fix this by registering devices as direct children of the bus
master.
(quoted diff) +1 -1
-	spi->dev.parent = dev;
+	spi->dev.parent = &master->dev;
}

Quoted 3 lines

Then my driver will be crash.
Maybe I have mistake on this issue, thank for your more explanation and detail replay.

Sounds like you've got a driver bug. Make sure it isn't trying to use the spi_client parent pointer to find the device instance.