linux-kernel - [ 073/117] HID: wiimote: work around broken DRM

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Date:	Tue, 24 Sep 2013 17:18:59 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, David Herrmann <dh.herrmann@...il.com>,
	Nicolas Adenis-Lamarre <nicolas.adenis.lamarre@...il.com>,
	Jiri Kosina <jkosina@...e.cz>
Subject: [ 073/117] HID: wiimote: work around broken DRM_KAI on GEN10

3.11-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Herrmann <dh.herrmann@...il.com>

commit a6be8569b6705cbc26e7ae1a8be476067cc5a78b upstream.

GEN10 and earlier devices seem to not support DRM_KAI if we run in basic
IR mode. Use DRM_KAIE instead. This might increases overhead slightly as
the extension port is read and streamed but we stream accelerometer data
constantly, too, so this is negligible.

Note that our parsers are hardcoded on IR-formats, so we cannot actually
use 96-bit IR DRMs for basic IR data. We would have to adjust the parsers.
But as only GEN20 and newer support this, we simply avoid mixed DRMs.

This fixes a bug where GEN10 devices didn't provide IR data if
accelerometer and IR are enabled simultaneously. As a workaround, you can
enable DRM_KAIE without this patch via (disables device power-management):
  echo "37" >/sys/kernel/debug/hid/<dev>/drm

Signed-off-by: David Herrmann <dh.herrmann@...il.com>
Reported-by: Nicolas Adenis-Lamarre <nicolas.adenis.lamarre@...il.com>
Signed-off-by: Jiri Kosina <jkosina@...e.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/hid/hid-wiimote-core.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

--- a/drivers/hid/hid-wiimote-core.c
+++ b/drivers/hid/hid-wiimote-core.c
@@ -212,10 +212,12 @@ static __u8 select_drm(struct wiimote_da

 	if (ir == WIIPROTO_FLAG_IR_BASIC) {
 		if (wdata->state.flags & WIIPROTO_FLAG_ACCEL) {
-			if (ext)
-				return WIIPROTO_REQ_DRM_KAIE;
-			else
-				return WIIPROTO_REQ_DRM_KAI;
+			/* GEN10 and ealier devices bind IR formats to DRMs.
+			 * Hence, we cannot use DRM_KAI here as it might be
+			 * bound to IR_EXT. Use DRM_KAIE unconditionally so we
+			 * work with all devices and our parsers can use the
+			 * fixed formats, too. */
+			return WIIPROTO_REQ_DRM_KAIE;
 		} else {
 			return WIIPROTO_REQ_DRM_KIE;
 		}

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