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authorPatrice Chotard <patrice.chotard@st.com>2013-04-11 11:01:27 +0200
committerLinus Walleij <linus.walleij@linaro.org>2013-04-26 17:01:35 +0200
commit42fed7ba44e4e8c1fb27b28ad14490cb1daff3c7 (patch)
tree3caafd69ed9807e9a15f14d6c482fa1f1a697a8b /drivers/pinctrl/pinmux.c
parentcb6d315dc36ce56bc017051befa9ac9391300eb9 (diff)
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pinctrl: move subsystem mutex to pinctrl_dev struct
This mutex avoids deadlock in case of use of multiple pin controllers. Before this modification, by using a global mutex, deadlock appeared when, for example, a call to pinctrl_pins_show() locked the pinctrl_mutex, called the ops->pin_dbg_show of a particular pin controller. If this pin controller needs I2C access to retrieve configuration information and I2C driver is using pinctrl to drive its pins, a call to pinctrl_select_state() try to lock again pinctrl_mutex which leads to a deadlock. Notice that the mutex grab from the two direction functions was moved into pinctrl_gpio_direction(). For several cases, we can't replace pinctrl_mutex by pctldev->mutex, because at this stage, pctldev is not accessible : - pinctrl_get()/pinctrl_put() - pinctrl_register_maps() So add respectively pinctrl_list_mutex and pinctrl_maps_mutex in order to protect pinctrl_list and pinctrl_maps list instead. Reintroduce pinctrldev_list_mutex in find_pinctrl_by_of_node(), pinctrl_find_and_add_gpio_range() pinctrl_request_gpio(), pinctrl_free_gpio(), pinctrl_gpio_direction(), pinctrl_devices_show(), pinctrl_register() and pinctrl_unregister() to protect pinctrldev_list. Changes v2->v3: - Fix a missing EXPORT_SYMBOL_GPL() for pinctrl_select_state(). Changes v1->v2: - pinctrl_select_state_locked() is removed, all lock mechanism is located inside pinctrl_select_state(). When parsing the state->setting list, take the per-pin-controller driver lock. (Patrice). - Introduce pinctrldev_list_mutex to protect pinctrldev_list in all functions which parse or modify pictrldev_list. (Patrice). - move find_pinctrl_by_of_node() from pinctrl/devicetree.c to pinctrl/core.c in order to protect pinctrldev_list. (Patrice). - Sink mutex:es into some functions and remove some _locked variants down to where the lists are actually accessed to make things simpler. (Linus) - Drop *all* mutexes completely from pinctrl_lookup_state() and pinctrl_select_state() - no relevant mutex was taken and it was unclear what this was protecting against. (Linus) Reported by : Seraphin Bonnaffe <seraphin.bonnaffe@stericsson.com> Signed-off-by: Patrice Chotard <patrice.chotard@st.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Diffstat (limited to 'drivers/pinctrl/pinmux.c')
-rw-r--r--drivers/pinctrl/pinmux.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/drivers/pinctrl/pinmux.c b/drivers/pinctrl/pinmux.c
index bd83c8b01cd1..88cc5095d0c9 100644
--- a/drivers/pinctrl/pinmux.c
+++ b/drivers/pinctrl/pinmux.c
@@ -506,7 +506,7 @@ static int pinmux_functions_show(struct seq_file *s, void *what)
if (!pmxops)
return 0;
- mutex_lock(&pinctrl_mutex);
+ mutex_lock(&pctldev->mutex);
nfuncs = pmxops->get_functions_count(pctldev);
while (func_selector < nfuncs) {
const char *func = pmxops->get_function_name(pctldev,
@@ -530,7 +530,7 @@ static int pinmux_functions_show(struct seq_file *s, void *what)
func_selector++;
}
- mutex_unlock(&pinctrl_mutex);
+ mutex_unlock(&pctldev->mutex);
return 0;
}
@@ -548,7 +548,7 @@ static int pinmux_pins_show(struct seq_file *s, void *what)
seq_puts(s, "Pinmux settings per pin\n");
seq_puts(s, "Format: pin (name): mux_owner gpio_owner hog?\n");
- mutex_lock(&pinctrl_mutex);
+ mutex_lock(&pctldev->mutex);
/* The pin number can be retrived from the pin controller descriptor */
for (i = 0; i < pctldev->desc->npins; i++) {
@@ -583,7 +583,7 @@ static int pinmux_pins_show(struct seq_file *s, void *what)
seq_printf(s, "\n");
}
- mutex_unlock(&pinctrl_mutex);
+ mutex_unlock(&pctldev->mutex);
return 0;
}