Re: [PATCH v4] pinctrl: to avoid duplicated calling enable_pinmux_setting for a pin
From: FanWu
Date: Tue Jun 03 2014 - 03:49:25 EST
On 06/03/2014 03:37 PM, fwu@xxxxxxxxxxx wrote:
From: Fan Wu <fwu@xxxxxxxxxxx>
What the patch did:
1.To call pinmux_disable_setting ahead of pinmux_enable_setting in each time of
calling pinctrl_select_state
2.Remove the HW disable operation in in pinmux_disable_setting function.
3.Remove the disable ops in struct pinmux_ops
The reason why to do this is that:
1.To avoid duplicated calling enable_setting operation without disabling
operation which will let Pin's desc->mux_usecount keep being added.
2.The HW pin disable operation is not useful for most of the vendors' platform.
And this can be used to avoid the HW glitch after using the item 1#
modification.
In the following case, the issue can be reproduced:
1)There is a driver need to switch Pin state dynamicly, E.g. b/t "sleep" and
"default" state
2)The Pin setting configuration in DTS node may be like the following one:
component a {
pinctrl-names = "default", "sleep";
pinctrl-0 = <&a_grp_setting &c_grp_setting>;
pinctrl-1 = <&b_grp_setting &c_grp_setting>;
}
The "c_grp_setting" config node is totaly same, maybe like following one:
c_grp_setting: c_grp_setting {
pinctrl-single,pins = <GPIO48 AF6>;
}
3)When switching the Pin state in the following official Pinctrl sequence:
pin = pinctrl_get();
state = pinctrl_lookup_state(wanted_state);
pinctrl_select_state(state);
pinctrl_put();
According to the comments in the original code, only the setting, in old state
but not in new state, will be "disable"(calling pinmux_disable_setting), which
is correct logic but not intact. We still need consider case that the setting
is in both old state and new state.
We can do this in the following two ways:
1) Avoid "enable"(calling pinmux_enable_setting) the Same Pins setting repeatedly.
2) "Disable"(calling pinmux_disable_setting) the "Same Pins setting", actually
two setting instance, ahead of enabling them.
Analysis:
1.The solution 2# is better because it can avoid too much iteration.
2.If we choose 2# solution, we need to
1) Should mark all the setting in disable state as disabled ahead of enabling.
2) Avoid the possible HW glitch by removing the HW disable ops in
in the pinmux_disable_setting
If we disable all of the settings in the old state and one/ones of the
setting(s) is/are existed in the new state, the Pin's mux function change
may happen when some SoC vendors defined the "pinctrl-single,function-off"
in their DTS file:
old_setting=>disabled_setting=>new_setting.(HW glitch)
Signed-off-by: Fan Wu <fwu@xxxxxxxxxxx>
Signed-off-by: Stephen Warren <swarren@xxxxxxxxxx>
---
drivers/pinctrl/core.c | 24 +++++-------------------
drivers/pinctrl/pinmux.c | 4 ----
include/linux/pinctrl/pinmux.h | 2 --
3 files changed, 5 insertions(+), 25 deletions(-)
diff --git a/drivers/pinctrl/core.c b/drivers/pinctrl/core.c
index c0fe609..4445a67 100644
--- a/drivers/pinctrl/core.c
+++ b/drivers/pinctrl/core.c
@@ -989,29 +989,15 @@ int pinctrl_select_state(struct pinctrl *p, struct pinctrl_state *state)
if (p->state) {
/*
- * The set of groups with a mux configuration in the old state
- * may not be identical to the set of groups with a mux setting
- * in the new state. While this might be unusual, it's entirely
- * possible for the "user"-supplied mapping table to be written
- * that way. For each group that was configured in the old state
- * but not in the new state, this code puts that group into a
- * safe/disabled state.
+ * For each pinmux setting in the old state, forget SW's record
+ * of mux owner for that pingroup. Any pingroups which are
+ * still owned by the new state will be re-acquired by the call
+ * to pinmux_enable_setting() in the loop below.
*/
list_for_each_entry(setting, &p->state->settings, node) {
- bool found = false;
if (setting->type != PIN_MAP_TYPE_MUX_GROUP)
continue;
- list_for_each_entry(setting2, &state->settings, node) {
- if (setting2->type != PIN_MAP_TYPE_MUX_GROUP)
- continue;
- if (setting2->data.mux.group ==
- setting->data.mux.group) {
- found = true;
- break;
- }
- }
- if (!found)
- pinmux_disable_setting(setting);
+ pinmux_disable_setting(setting);
}
}
diff --git a/drivers/pinctrl/pinmux.c b/drivers/pinctrl/pinmux.c
index 9248ce4..c2c4aff 100644
--- a/drivers/pinctrl/pinmux.c
+++ b/drivers/pinctrl/pinmux.c
@@ -469,7 +469,6 @@ void pinmux_disable_setting(struct pinctrl_setting const *setting)
{
struct pinctrl_dev *pctldev = setting->pctldev;
const struct pinctrl_ops *pctlops = pctldev->desc->pctlops;
- const struct pinmux_ops *ops = pctldev->desc->pmxops;
int ret;
const unsigned *pins;
unsigned num_pins;
@@ -515,9 +514,6 @@ void pinmux_disable_setting(struct pinctrl_setting const *setting)
pins[i], desc->name, gname);
}
}
-
- if (ops->disable)
- ops->disable(pctldev, setting->data.mux.func, setting->data.mux.group);
}
#ifdef CONFIG_DEBUG_FS
diff --git a/include/linux/pinctrl/pinmux.h b/include/linux/pinctrl/pinmux.h
index c153950..3097aaf 100644
--- a/include/linux/pinctrl/pinmux.h
+++ b/include/linux/pinctrl/pinmux.h
@@ -70,8 +70,6 @@ struct pinmux_ops {
unsigned * const num_groups);
int (*enable) (struct pinctrl_dev *pctldev, unsigned func_selector,
unsigned group_selector);
- void (*disable) (struct pinctrl_dev *pctldev, unsigned func_selector,
- unsigned group_selector);
int (*gpio_request_enable) (struct pinctrl_dev *pctldev,
struct pinctrl_gpio_range *range,
unsigned offset);
Dear All,
I have updated the patch and the main modification includes:
1.To remove the disable ops in the struct pinmux_ops.
2.To short the patch comments.
Please help to review.
For the "signed-off" part, I added the "Stephen" because I change the
code inline comments according to the suggestion from Stephen.
Please share your suggestion about the new version patch.
Great thanks for this!
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/