ARM: OMAP: fix the ads7846 init code

In case a board provides the gpio_pendown and not board_pdata, the GPIO debounce is not taken care of.
Fix this by taking care of GPIO debounce in any case.

Signed-off-by Igor Grinberg <[email protected]>

---
 arch/arm/mach-omap2/common-board-devices.c |   22 ++++++++++++----------
 1 files changed, 12 insertions(+), 10 deletions(-)

arch/arm/mach-omap2/common-board-devices.c +7 -10

index 1706ebc..c187586 100644
@@ -63,28 +63,30 @@ void __init omap_ads7846_init(int bus_num, int gpio_pendown, int gpio_debounce,
 	struct spi_board_info *spi_bi = &ads7846_spi_board_info;
 	int err;
 
-	if (board_pdata && board_pdata->get_pendown_state) {
-		err = gpio_request_one(gpio_pendown, GPIOF_IN, "TSPenDown");
-		if (err) {
-			pr_err("Couldn't obtain gpio for TSPenDown: %d\n", err);
-			return;
-		}
-		gpio_export(gpio_pendown, 0);
-
-		if (gpio_debounce)
-			gpio_set_debounce(gpio_pendown, gpio_debounce);
+	err = gpio_request_one(gpio_pendown, GPIOF_IN, "TSPenDown");
+	if (err) {
+		pr_err("Couldn't obtain gpio for TSPenDown: %d\n", err);
+		return;
 	}
 
+	if (gpio_debounce)
+		gpio_set_debounce(gpio_pendown, gpio_debounce);
+
 	spi_bi->bus_num	= bus_num;
 	spi_bi->irq	= gpio_to_irq(gpio_pendown);
 
 	if (board_pdata) {

From bb87c3b5586950e480d0699504997a9ad587fd85 Mon Sep 17 00:00:00 2001

Hi Igor,

Igor Grinberg <[email protected]> writes:

Quoted 5 lines

In case a board provides the gpio_pendown and not board_pdata, the GPIO debounce is not taken care of.
Fix this by taking care of GPIO debounce in any case.

Signed-off-by Igor Grinberg <[email protected]>

I just notice this this patch causing some faults in current l-o master branch.

Quoted 44 lines

---
 arch/arm/mach-omap2/common-board-devices.c |   22 ++++++++++++----------
 1 files changed, 12 insertions(+), 10 deletions(-)

arch/arm/mach-omap2/common-board-devices.c +9 -10

index 1706ebc..c187586 100644
@@ -63,28 +63,30 @@ void __init omap_ads7846_init(int bus_num, int gpio_pendown, int gpio_debounce,
 	struct spi_board_info *spi_bi = &ads7846_spi_board_info;
 	int err;
 
-	if (board_pdata && board_pdata->get_pendown_state) {
-		err = gpio_request_one(gpio_pendown, GPIOF_IN, "TSPenDown");
-		if (err) {
-			pr_err("Couldn't obtain gpio for TSPenDown: %d\n", err);
-			return;
-		}
-		gpio_export(gpio_pendown, 0);
-
-		if (gpio_debounce)
-			gpio_set_debounce(gpio_pendown, gpio_debounce);
+	err = gpio_request_one(gpio_pendown, GPIOF_IN, "TSPenDown");
+	if (err) {
+		pr_err("Couldn't obtain gpio for TSPenDown: %d\n", err);
+		return;
 	}
 
+	if (gpio_debounce)
+		gpio_set_debounce(gpio_pendown, gpio_debounce);
+
 	spi_bi->bus_num	= bus_num;
 	spi_bi->irq	= gpio_to_irq(gpio_pendown);
 
 	if (board_pdata) {
 		board_pdata->gpio_pendown = gpio_pendown;
 		spi_bi->platform_data = board_pdata;
+		if (board_pdata->get_pendown_state)
+			gpio_export(gpio_pendown, 0);
 	} else {
 		ads7846_config.gpio_pendown = gpio_pendown;
 	}
 

arch/arm/mach-omap2/common-board-devices.c void __init omap_ads7846_init(int bus_num, int gpio_pendown, int gpio_debounce, · line 88

Quoted 2 lines

arch/arm/mach-omap2/common-board-devices.c +2 -0

+	if (!board_pdata || (board_pdata && !board_pdata->get_pendown_state))
+		gpio_free(gpio_pendown);

The logic here for freeing the GPIO doesn't make any sense to me. IIUC, the gpio_pendown is always used, so should not be freed.

Moreover, if this GPIO is freed, that allows that GPIO bank to runtime suspend if there are no other GPIOs in use in that bank. So the first attempt to use the GPIO will fault.

For example, on my Overo board(s), I noticed this failing as soon as teh ads7846 driver probes, requests the IRQ and the GPIO triggering is set.

Getting rid of this free fixes the problem.

The changelog doesn't describe why the GPIO is freed here so I'm not sure I follow, but it seems to me that once this GPIO is requesed, it should not be freed as long as it's used, otherwise PM faults can occur.

Kevin

Quoted 1 line

From bb87c3b5586950e480d0699504997a9ad587fd85 Mon Sep 17 00:00:00 2001

From: Kevin Hilman <[email protected]>
Date: Wed, 11 Jul 2012 15:47:29 -0700
Subject: [PATCH] ARM: OMAP2+: ads7846 init: fix fault caused by freeing
pen-down GPIO

commit 97ee9f01d6 (ARM: OMAP: fix the ads7846 init code) mistakenly frees the pen-down GPIO even though it will be used by the ads7846 driver.

Freeing a GPIO means that the GPIO bank containing that GPIO can be runtime suspended if its the last/only GPIO being used in that bank. If the GPIO bank is runtime suspended, any accesses to that bank will cause faults.

Because the current code frees the GPIO, the ads7846 driver probe will fault when it requests its IRQ line. Because the IRQ is a GPIO line, the request IRQ will trickle down into the OMAP GPIO layer:
gpio_irq_type() --> _set_gpio_triggering() which can fault if the bank has been runtime suspended.

This is exctly what happens on Overo platforms (3530 Water, 3730 Overo FireSTORM) since this is the only GPIO used in the bank.

To fix, don't free the GPIO at all since it is always in use.

Cc Igor Grinberg <[email protected]>

Signed-off-by Kevin Hilman <[email protected]>

---
 arch/arm/mach-omap2/common-board-devices.c |    3 ---
 1 file changed, 3 deletions(-)

arch/arm/mach-omap2/common-board-devices.c +0 -3

index c187586..1ae6fd6 100644
@@ -84,9 +84,6 @@ void __init omap_ads7846_init(int bus_num, int gpio_pendown, int gpio_debounce,
 		ads7846_config.gpio_pendown = gpio_pendown;
 	}
 
-	if (!board_pdata || (board_pdata && !board_pdata->get_pendown_state))
-		gpio_free(gpio_pendown);
-
 	spi_register_board_info(&ads7846_spi_board_info, 1);
 }
 #else