Re: [PATCH] hid: Support for Litra Glow

[Bastien Nocera]

On Fri, 2022-12-16 at 10:53 +0100, Bastien Nocera wrote:
> On Thu, 2022-12-15 at 22:09 +0100, Andreas Bergmeier wrote:
> > Tries to implement as general support for Illumination Light as
> > possible. Note that it is singular, which means by Logitech spec we
> > are
> > fine off with just handling one capability/device.
> 
> Your email client absolutely trashed the patch's indentation, it's
> unreadable as-is.
> 
> > Implementation currently only exposes Brightness and On/Off
> > controls.
> > Does currently not expose Color Temperature because LEDs does not
> > support it.
> > 
> > Introduces HIDPP_QUIRK_CLASS_SIMPLE_START to prevent reconnect on
> > startup. Could not get Glow to work with that.
> 
> I'd really rather we didn't introduce a new quirk, but instead fixed
> the fact that we need to restart the HID transport to support 3 (!)
> devices.
> 
> Would something like the attached patch work? I haven't tested it
> yet,
> but if it works for you, I'll test it on the devices I have here.

A tested version attached. I'll need to test it against a T650 before
sending it for review.
From beae2de086546f6a3187a31f2f406b1e3fe21f5e Mon Sep 17 00:00:00 2001
From: Bastien Nocera <hadess@xxxxxxxxxx>
Date: Fri, 16 Dec 2022 10:41:16 +0100
Subject: [PATCH] HID: logitech-hidpp: Don't restart communication if not
 necessary

Don't stop and restart communication with the device unless we need to
modify the connect flags used because of a device quirk.
---
 drivers/hid/hid-logitech-hidpp.c | 31 +++++++++++++++++++------------
 1 file changed, 19 insertions(+), 12 deletions(-)

diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c
index 7f9187201913..b4e4a8c79c75 100644
--- a/drivers/hid/hid-logitech-hidpp.c
+++ b/drivers/hid/hid-logitech-hidpp.c
@@ -4310,6 +4310,7 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id)
 	bool connected;
 	unsigned int connect_mask = HID_CONNECT_DEFAULT;
 	struct hidpp_ff_private_data data;
+	bool will_restart = false;
 
 	/* report_fixup needs drvdata to be set before we call hid_parse */
 	hidpp = devm_kzalloc(&hdev->dev, sizeof(*hidpp), GFP_KERNEL);
@@ -4360,6 +4361,9 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id)
 			return ret;
 	}
 
+	if (hidpp->quirks & HIDPP_QUIRK_DELAYED_INIT)
+		will_restart = true;
+
 	INIT_WORK(&hidpp->work, delayed_work_cb);
 	mutex_init(&hidpp->send_mutex);
 	init_waitqueue_head(&hidpp->wait);
@@ -4374,7 +4378,7 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id)
 	 * Plain USB connections need to actually call start and open
 	 * on the transport driver to allow incoming data.
 	 */
-	ret = hid_hw_start(hdev, 0);
+	ret = hid_hw_start(hdev, will_restart ? 0 : connect_mask);
 	if (ret) {
 		hid_err(hdev, "hw start failed\n");
 		goto hid_hw_start_fail;
@@ -4411,6 +4415,7 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id)
 			hidpp->wireless_feature_index = 0;
 		else if (ret)
 			goto hid_hw_init_fail;
+		ret = 0;
 	}
 
 	if (connected && (hidpp->quirks & HIDPP_QUIRK_CLASS_WTP)) {
@@ -4425,19 +4430,21 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id)
 
 	hidpp_connect_event(hidpp);
 
-	/* Reset the HID node state */
-	hid_device_io_stop(hdev);
-	hid_hw_close(hdev);
-	hid_hw_stop(hdev);
+	if (will_restart) {
+		/* Reset the HID node state */
+		hid_device_io_stop(hdev);
+		hid_hw_close(hdev);
+		hid_hw_stop(hdev);
 
-	if (hidpp->quirks & HIDPP_QUIRK_NO_HIDINPUT)
-		connect_mask &= ~HID_CONNECT_HIDINPUT;
+		if (hidpp->quirks & HIDPP_QUIRK_NO_HIDINPUT)
+			connect_mask &= ~HID_CONNECT_HIDINPUT;
 
-	/* Now export the actual inputs and hidraw nodes to the world */
-	ret = hid_hw_start(hdev, connect_mask);
-	if (ret) {
-		hid_err(hdev, "%s:hid_hw_start returned error\n", __func__);
-		goto hid_hw_start_fail;
+		/* Now export the actual inputs and hidraw nodes to the world */
+		ret = hid_hw_start(hdev, connect_mask);
+		if (ret) {
+			hid_err(hdev, "%s:hid_hw_start returned error\n", __func__);
+			goto hid_hw_start_fail;
+		}
 	}
 
 	if (hidpp->quirks & HIDPP_QUIRK_CLASS_G920) {
-- 
2.38.1