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authorVladimir Zapolskiy <vz@mleia.com>2019-01-23 00:18:22 +0300
committerLinus Walleij <linus.walleij@linaro.org>2019-01-28 16:39:52 +0300
commite73339037f6b6d65e84f5fd42e56dd3cdf0d9e9c (patch)
tree3a1fa2ab93a9378e79d36b175df795021e5d4e01 /include/linux/pinctrl
parent87eff9af7efb154cc4a940ed12efc803a0bf3fba (diff)
downloadlinux-e73339037f6b6d65e84f5fd42e56dd3cdf0d9e9c.tar.xz
pinctrl: remove unused 'pinconf-config' debugfs interface
The main goal of the change is to remove .pin_config_dbg_parse_modify callback before a driver with its support appears. So far the in-kernel interface did not attract any users since its introduction 5 years ago. Originally .pin_config_dbg_parse_modify callback and the associated 'pinconf-config' debugfs file were introduced in commit f07512e615dd ("pinctrl/pinconfig: add debug interface"), a short description of 'pinconf-config' usage for debugging can be expressed this way: Write to 'pinconf-config' (see pinconf_dbg_config_write() function): % echo -n modify $map_type $device_name $state_name $pin_name $config > \ /sys/kernel/debug/pinctrl/$pinctrl/pinconf-config It supposes to update a global (therefore single!) 'pinconf_dbg_conf' variable with an alternative setting, the arguments should match an existing pinconf device and some registered pinctrl mapping 'map': * $map_type is either 'config_pin' or 'config_group', it should match 'map->type' value of PIN_MAP_TYPE_CONFIGS_PIN or PIN_MAP_TYPE_CONFIGS_GROUP accordingly, * $device_name should match 'map->dev_name' string value, * $state_name should match 'map->name' string value, * $pin_name should match 'map->data.configs.group_or_pin' string value, If all above has matched, then $config is a new value to be set by calling pinconfops->pin_config_dbg_parse_modify(pctldev, config, matched_config). After a successful write into 'pinconf-config' a user can read the file to get information about that single modified pin configuration. The fact is .pin_config_dbg_parse_modify callback has never been defined in 'struct pinconf_ops' of any pinconf driver, thus an actual modification of a pin or group state on any present pinconf controller does not happen, and it declares that all related code is no more than dead code. I discovered the issue while attempting to add .pin_config_dbg_parse_modify support in some drivers and found that too short 'MAX_NAME_LEN' set by drivers/pinctrl/pinconf.c:372:#define MAX_NAME_LEN 15 is practically insufficient to store a regular pinctrl device name, which are like 'e6060000.pin-controller-sh-pfc' or pin names like 'MX6QDL_PAD_ENET_REF_CLK', thus it is another indicator that the code is barely usable, insufficiently tested and unprepossessing. Of course it might be possible to increase MAX_NAME_LEN, and then add .pin_config_dbg_parse_modify callbacks to the drivers, but the whole idea of such a limited debug option looks inviable. A more flexible way to functionally substitute the original approach is to implicitly or explicitly use pinctrl_select_state() function whenever needed. Signed-off-by: Vladimir Zapolskiy <vz@mleia.com> Cc: Laurent Meunier <laurent.meunier@st.com> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Russell King <linux@arm.linux.org.uk> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Diffstat (limited to 'include/linux/pinctrl')
-rw-r--r--include/linux/pinctrl/pinconf.h4
1 files changed, 0 insertions, 4 deletions
diff --git a/include/linux/pinctrl/pinconf.h b/include/linux/pinctrl/pinconf.h
index 109468d9d849..93c9dd133e9d 100644
--- a/include/linux/pinctrl/pinconf.h
+++ b/include/linux/pinctrl/pinconf.h
@@ -29,7 +29,6 @@ struct seq_file;
* @pin_config_group_get: get configurations for an entire pin group; should
* return -ENOTSUPP and -EINVAL using the same rules as pin_config_get.
* @pin_config_group_set: configure all pins in a group
- * @pin_config_dbg_parse_modify: optional debugfs to modify a pin configuration
* @pin_config_dbg_show: optional debugfs display hook that will provide
* per-device info for a certain pin in debugfs
* @pin_config_group_dbg_show: optional debugfs display hook that will provide
@@ -55,9 +54,6 @@ struct pinconf_ops {
unsigned selector,
unsigned long *configs,
unsigned num_configs);
- int (*pin_config_dbg_parse_modify) (struct pinctrl_dev *pctldev,
- const char *arg,
- unsigned long *config);
void (*pin_config_dbg_show) (struct pinctrl_dev *pctldev,
struct seq_file *s,
unsigned offset);