Re: usb: common: usb-conn-gpio: Prevent bailing out if initial role is none

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On 25-07-23 09:04 pm, Greg Kroah-Hartman wrote:
On Thu, Jul 06, 2023 at 03:40:58PM +0530, Prashanth K wrote:
Currently if we bootup a device without cable connected, then
usb-conn-gpio won't call set_role() since last_role is same as
current role. This happens because during probe last_role gets
initialised to zero.

To avoid this, add a new flag initial_det in usb_conn_info,
which is used to prevent bailing out during init detection.

Fixes: 4602f3bff266 ("usb: common: add USB GPIO based connection detection driver")
Signed-off-by: Prashanth K <quic_prashk@xxxxxxxxxxx>
---
  drivers/usb/common/usb-conn-gpio.c | 6 +++++-
  1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/common/usb-conn-gpio.c b/drivers/usb/common/usb-conn-gpio.c
index 766005d..46290ff 100644
--- a/drivers/usb/common/usb-conn-gpio.c
+++ b/drivers/usb/common/usb-conn-gpio.c
@@ -42,6 +42,7 @@ struct usb_conn_info {
struct power_supply_desc desc;
  	struct power_supply *charger;
+	bool initial_det;

What does "initial_det" mean?  Please document this better.

Yea sure, will update that. It was supposed to mean initial_detection.
  };
/*
@@ -86,11 +87,13 @@ static void usb_conn_detect_cable(struct work_struct *work)
  	dev_dbg(info->dev, "role %s -> %s, gpios: id %d, vbus %d\n",
  		usb_role_string(info->last_role), usb_role_string(role), id, vbus);
- if (info->last_role == role) {
+	if (!info->initial_det && info->last_role == role) {
  		dev_warn(info->dev, "repeated role: %s\n", usb_role_string(role));
  		return;
  	}
+ info->initial_det = false;
+
  	if (info->last_role == USB_ROLE_HOST && info->vbus)
  		regulator_disable(info->vbus);
@@ -258,6 +261,7 @@ static int usb_conn_probe(struct platform_device *pdev)
  	device_set_wakeup_capable(&pdev->dev, true);
/* Perform initial detection */
+	info->initial_det = true;

What is protecting this from changing right after you test for it?

thanks,

greg k-h

Hi Greg, this variable is only used/changed by usb_conn_detect_cable() which is called in next line. So the chance of it changing is none.
Basically this initial_det flag points if its initial detection or not.
If yes, then prevent bailing out in usb_conn_detect_cable(). Please let me know if your comment was regarding something else.

Regards,
Prashanth K



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