diff mbox series

[7/9] HID: i2c-hid: Support being a panel follower

Message ID 20230523122802.7.Ib1a98309c455cd7e26b931c69993d4fba33bbe15@changeid (mailing list archive)
State New, archived
Headers show
Series drm/panel and i2c-hid: Allow panels and touchscreens to power sequence together | expand

Commit Message

Doug Anderson May 23, 2023, 7:28 p.m. UTC 
As talked about in the patch ("drm/panel: Add a way for other devices
to follow panel state"), we really want to keep the power states of a
touchscreen and the panel it's attached to in sync with each other. In
that spirit, add support to i2c-hid to be a panel follower. This will
let the i2c-hid driver get informed when the panel is powered on and
off. From there we can match the i2c-hid device's power state to that
of the panel.

NOTE: this patch specifically _doesn't_ use pm_runtime to keep track
of / manage the power state of the i2c-hid device, even though my
first instinct said that would be the way to go. Specific problems
with using pm_runtime():
* The initial power up couldn't happen in a runtime resume function
  since it create sub-devices and, apparently, that's not good to do
  in your resume function.
* Managing our power state with pm_runtime meant fighting to make the
  right thing happen at system suspend to prevent the system from
  trying to resume us only to suspend us again. While this might be
  able to be solved, it added complexity.
Overall the code without pm_runtime() ended up being smaller and
easier to understand.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
---

 drivers/hid/i2c-hid/i2c-hid-core.c | 82 +++++++++++++++++++++++++++++-
 1 file changed, 81 insertions(+), 1 deletion(-)

Comments

kernel test robot May 24, 2023, 12:28 a.m. UTC | #1 
Hi Douglas,

kernel test robot noticed the following build warnings:

[auto build test WARNING on robh/for-next]
[also build test WARNING on hid/for-next drm-misc/drm-misc-next linus/master v6.4-rc3 next-20230523]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Douglas-Anderson/dt-bindings-HID-i2c-hid-Add-panel-property-to-i2c-hid-backed-panels/20230524-034323
base:   https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git for-next
patch link:    https://lore.kernel.org/r/20230523122802.7.Ib1a98309c455cd7e26b931c69993d4fba33bbe15%40changeid
patch subject: [PATCH 7/9] HID: i2c-hid: Support being a panel follower
config: m68k-allyesconfig
compiler: m68k-linux-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/fff5c7d6358fe0a778218b49582351e53040595d
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Douglas-Anderson/dt-bindings-HID-i2c-hid-Add-panel-property-to-i2c-hid-backed-panels/20230524-034323
        git checkout fff5c7d6358fe0a778218b49582351e53040595d
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=m68k olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=m68k SHELL=/bin/bash drivers/hid/i2c-hid/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202305240845.bJhmT3Im-lkp@intel.com/

All warnings (new ones prefixed by >>):

   drivers/hid/i2c-hid/i2c-hid-core.c:1011:5: warning: no previous prototype for 'i2c_hid_core_initial_power_up' [-Wmissing-prototypes]
    1011 | int i2c_hid_core_initial_power_up(struct i2c_hid *ihid)
         |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> drivers/hid/i2c-hid/i2c-hid-core.c:1065:5: warning: no previous prototype for 'i2c_hid_core_panel_prepared' [-Wmissing-prototypes]
    1065 | int i2c_hid_core_panel_prepared(struct drm_panel_follower *follower)
         |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~
>> drivers/hid/i2c-hid/i2c-hid-core.c:1081:5: warning: no previous prototype for 'i2c_hid_core_panel_unpreparing' [-Wmissing-prototypes]
    1081 | int i2c_hid_core_panel_unpreparing(struct drm_panel_follower *follower)
         |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


vim +/i2c_hid_core_panel_prepared +1065 drivers/hid/i2c-hid/i2c-hid-core.c

  1064	
> 1065	int i2c_hid_core_panel_prepared(struct drm_panel_follower *follower)
  1066	{
  1067		struct i2c_hid *ihid = container_of(follower, struct i2c_hid, panel_follower);
  1068		struct hid_device *hid = ihid->hid;
  1069	
  1070		/*
  1071		 * hid->version is set on the first power up. If it's still zero then
  1072		 * this is the first power on so we should perform initial power up
  1073		 * steps.
  1074		 */
  1075		if (!hid->version)
  1076			return i2c_hid_core_initial_power_up(ihid);
  1077	
  1078		return i2c_hid_core_resume(ihid);
  1079	}
  1080	
> 1081	int i2c_hid_core_panel_unpreparing(struct drm_panel_follower *follower)
  1082	{
  1083		struct i2c_hid *ihid = container_of(follower, struct i2c_hid, panel_follower);
  1084	
  1085		return i2c_hid_core_suspend(ihid);
  1086	}
  1087
kernel test robot May 24, 2023, 3:37 p.m. UTC | #2 
Hi Douglas,

kernel test robot noticed the following build warnings:

[auto build test WARNING on robh/for-next]
[also build test WARNING on hid/for-next drm-misc/drm-misc-next linus/master v6.4-rc3 next-20230524]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Douglas-Anderson/dt-bindings-HID-i2c-hid-Add-panel-property-to-i2c-hid-backed-panels/20230524-034323
base:   https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git for-next
patch link:    https://lore.kernel.org/r/20230523122802.7.Ib1a98309c455cd7e26b931c69993d4fba33bbe15%40changeid
patch subject: [PATCH 7/9] HID: i2c-hid: Support being a panel follower
config: i386-randconfig-s001
compiler: gcc-11 (Debian 11.3.0-12) 11.3.0
reproduce:
        # apt-get install sparse
        # sparse version: v0.6.4-39-gce1a6720-dirty
        # https://github.com/intel-lab-lkp/linux/commit/fff5c7d6358fe0a778218b49582351e53040595d
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Douglas-Anderson/dt-bindings-HID-i2c-hid-Add-panel-property-to-i2c-hid-backed-panels/20230524-034323
        git checkout fff5c7d6358fe0a778218b49582351e53040595d
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=i386 olddefconfig
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=i386 SHELL=/bin/bash drivers/hid/i2c-hid/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202305242307.RcUHT7WO-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
   drivers/hid/i2c-hid/i2c-hid-core.c:1011:5: sparse: sparse: symbol 'i2c_hid_core_initial_power_up' was not declared. Should it be static?
>> drivers/hid/i2c-hid/i2c-hid-core.c:1065:5: sparse: sparse: symbol 'i2c_hid_core_panel_prepared' was not declared. Should it be static?
>> drivers/hid/i2c-hid/i2c-hid-core.c:1081:5: sparse: sparse: symbol 'i2c_hid_core_panel_unpreparing' was not declared. Should it be static?
Doug Anderson May 24, 2023, 5:29 p.m. UTC | #3 
Hi,

On Tue, May 23, 2023 at 12:31 PM Douglas Anderson <dianders@chromium.org> wrote:
>
> As talked about in the patch ("drm/panel: Add a way for other devices
> to follow panel state"), we really want to keep the power states of a
> touchscreen and the panel it's attached to in sync with each other. In
> that spirit, add support to i2c-hid to be a panel follower. This will
> let the i2c-hid driver get informed when the panel is powered on and
> off. From there we can match the i2c-hid device's power state to that
> of the panel.
>
> NOTE: this patch specifically _doesn't_ use pm_runtime to keep track
> of / manage the power state of the i2c-hid device, even though my
> first instinct said that would be the way to go. Specific problems
> with using pm_runtime():
> * The initial power up couldn't happen in a runtime resume function
>   since it create sub-devices and, apparently, that's not good to do
>   in your resume function.
> * Managing our power state with pm_runtime meant fighting to make the
>   right thing happen at system suspend to prevent the system from
>   trying to resume us only to suspend us again. While this might be
>   able to be solved, it added complexity.
> Overall the code without pm_runtime() ended up being smaller and
> easier to understand.
>
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> ---
>
>  drivers/hid/i2c-hid/i2c-hid-core.c | 82 +++++++++++++++++++++++++++++-
>  1 file changed, 81 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/hid/i2c-hid/i2c-hid-core.c b/drivers/hid/i2c-hid/i2c-hid-core.c
> index 34c0d98b4976..f1bb89377e8d 100644
> --- a/drivers/hid/i2c-hid/i2c-hid-core.c
> +++ b/drivers/hid/i2c-hid/i2c-hid-core.c
> @@ -38,6 +38,8 @@
>  #include <linux/mutex.h>
>  #include <asm/unaligned.h>
>
> +#include <drm/drm_panel.h>
> +
>  #include "../hid-ids.h"
>  #include "i2c-hid.h"
>
> @@ -107,6 +109,8 @@ struct i2c_hid {
>         struct mutex            reset_lock;
>
>         struct i2chid_ops       *ops;
> +       struct drm_panel_follower panel_follower;
> +       bool                    is_panel_follower;
>  };
>
>  static const struct i2c_hid_quirks {
> @@ -1058,6 +1062,34 @@ int i2c_hid_core_initial_power_up(struct i2c_hid *ihid)
>         return ret;
>  }
>
> +int i2c_hid_core_panel_prepared(struct drm_panel_follower *follower)

As pointed out by the kernel test robot, I clearly missed making
several functions "static" in this patch series. :( I'll fix that in
v2, but for now I'll hold off sending v2 to wait for additional
feedback.

-Doug
diff mbox series

Patch

diff --git a/drivers/hid/i2c-hid/i2c-hid-core.c b/drivers/hid/i2c-hid/i2c-hid-core.c
index 34c0d98b4976..f1bb89377e8d 100644
--- a/drivers/hid/i2c-hid/i2c-hid-core.c
+++ b/drivers/hid/i2c-hid/i2c-hid-core.c
@@ -38,6 +38,8 @@ 
 #include <linux/mutex.h>
 #include <asm/unaligned.h>
 
+#include <drm/drm_panel.h>
+
 #include "../hid-ids.h"
 #include "i2c-hid.h"
 
@@ -107,6 +109,8 @@  struct i2c_hid {
 	struct mutex		reset_lock;
 
 	struct i2chid_ops	*ops;
+	struct drm_panel_follower panel_follower;
+	bool			is_panel_follower;
 };
 
 static const struct i2c_hid_quirks {
@@ -1058,6 +1062,34 @@  int i2c_hid_core_initial_power_up(struct i2c_hid *ihid)
 	return ret;
 }
 
+int i2c_hid_core_panel_prepared(struct drm_panel_follower *follower)
+{
+	struct i2c_hid *ihid = container_of(follower, struct i2c_hid, panel_follower);
+	struct hid_device *hid = ihid->hid;
+
+	/*
+	 * hid->version is set on the first power up. If it's still zero then
+	 * this is the first power on so we should perform initial power up
+	 * steps.
+	 */
+	if (!hid->version)
+		return i2c_hid_core_initial_power_up(ihid);
+
+	return i2c_hid_core_resume(ihid);
+}
+
+int i2c_hid_core_panel_unpreparing(struct drm_panel_follower *follower)
+{
+	struct i2c_hid *ihid = container_of(follower, struct i2c_hid, panel_follower);
+
+	return i2c_hid_core_suspend(ihid);
+}
+
+static const struct drm_panel_follower_funcs i2c_hid_core_panel_follower_funcs = {
+	.panel_prepared = i2c_hid_core_panel_prepared,
+	.panel_unpreparing = i2c_hid_core_panel_unpreparing,
+};
+
 int i2c_hid_core_probe(struct i2c_client *client, struct i2chid_ops *ops,
 		       u16 hid_descriptor_address, u32 quirks)
 {
@@ -1119,6 +1151,41 @@  int i2c_hid_core_probe(struct i2c_client *client, struct i2chid_ops *ops,
 	hid->bus = BUS_I2C;
 	hid->initial_quirks = quirks;
 
+	/*
+	 * See if we're following a panel. If drm_panel_add_follower()
+	 * returns no error then we are.
+	 */
+	ihid->panel_follower.funcs = &i2c_hid_core_panel_follower_funcs;
+	ret = drm_panel_add_follower(&client->dev, &ihid->panel_follower);
+	if (!ret) {
+		/* We're a follower. That means we'll power things up later. */
+		ihid->is_panel_follower = true;
+
+		/*
+		 * If we're not in control of our own power up/power down then
+		 * we can't do the logic to manage wakeups. Give a warning if
+		 * a user thought that was possible then force the capability
+		 * off.
+		 */
+		if (device_can_wakeup(&client->dev)) {
+			dev_warn(&client->dev, "Can't wakeup if following panel\n");
+			device_set_wakeup_capable(&client->dev, false);
+		}
+
+		return 0;
+	}
+
+	/*
+	 * -ENODEV means that we're not following a panel, so any other error
+	 * is a real problem (like -EPROBE_DEFER, -ENOMEM, ...).
+	 */
+	if (ret != -ENODEV)
+		goto err_mem_free;
+
+	/*
+	 * We're not following a panel. That's fine and means that we
+	 * can power up right away.
+	 */
 	ret = i2c_hid_core_initial_power_up(ihid);
 	if (ret)
 		goto err_mem_free;
@@ -1143,7 +1210,14 @@  void i2c_hid_core_remove(struct i2c_client *client)
 	struct i2c_hid *ihid = i2c_get_clientdata(client);
 	struct hid_device *hid;
 
-	i2c_hid_core_power_down(ihid);
+	/*
+	 * If we're a follower, the act of unfollowing will cause us to be
+	 * powered down. Otherwise we need to manually do it.
+	 */
+	if (ihid->is_panel_follower)
+		drm_panel_remove_follower(&ihid->panel_follower);
+	else
+		i2c_hid_core_power_down(ihid);
 
 	hid = ihid->hid;
 	hid_destroy_device(hid);
@@ -1171,6 +1245,9 @@  static int i2c_hid_core_pm_suspend(struct device *dev)
 	struct i2c_client *client = to_i2c_client(dev);
 	struct i2c_hid *ihid = i2c_get_clientdata(client);
 
+	if (ihid->is_panel_follower)
+		return 0;
+
 	return i2c_hid_core_suspend(ihid);
 }
 
@@ -1179,6 +1256,9 @@  static int i2c_hid_core_pm_resume(struct device *dev)
 	struct i2c_client *client = to_i2c_client(dev);
 	struct i2c_hid *ihid = i2c_get_clientdata(client);
 
+	if (ihid->is_panel_follower)
+		return 0;
+
 	return i2c_hid_core_resume(ihid);
 }