From 3669639b2162d0ec0d3f9b47b2e443b6d89d1cee Mon Sep 17 00:00:00 2001
From: Keith Whitwell <keith@tungstengraphics.com>
Date: Fri, 11 Jul 2003 15:27:55 +0000
Subject: Restore __HAVE_KERNEL_CTX_SWITCH, required for the sparc drm module
 in the     kernel tree. Added comments to that effect.

---
 linux-core/drm_drv.c | 43 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 42 insertions(+), 1 deletion(-)

(limited to 'linux-core')

diff --git a/linux-core/drm_drv.c b/linux-core/drm_drv.c
index 30a6b6e4..016f9195 100644
--- a/linux-core/drm_drv.c
+++ b/linux-core/drm_drv.c
@@ -88,6 +88,13 @@
 #ifndef __HAVE_SG
 #define __HAVE_SG			0
 #endif
+/* __HAVE_KERNEL_CTX_SWITCH isn't used by any of the drm modules in
+ * the DRI cvs tree, but it is required by the kernel tree's sparc
+ * driver.
+ */
+#ifndef __HAVE_KERNEL_CTX_SWITCH
+#define __HAVE_KERNEL_CTX_SWITCH	0
+#endif
 #ifndef __HAVE_DRIVER_FOPS_READ
 #define __HAVE_DRIVER_FOPS_READ		0
 #endif
@@ -1104,6 +1111,16 @@ int DRM(lock)( struct inode *inode, struct file *filp,
                 if ( lock.flags & _DRM_LOCK_QUIESCENT ) {
 			DRIVER_DMA_QUIESCENT();
 		}
+#endif
+		/* __HAVE_KERNEL_CTX_SWITCH isn't used by any of the
+		 * drm modules in the DRI cvs tree, but it is required
+		 * by the Sparc driver.
+		 */
+#if __HAVE_KERNEL_CTX_SWITCH
+		if ( dev->last_context != lock.context ) {
+			DRM(context_switch)(dev, dev->last_context,
+					    lock.context);
+		}
 #endif
         }
 
@@ -1141,6 +1158,29 @@ int DRM(unlock)( struct inode *inode, struct file *filp,
 
 	atomic_inc( &dev->counts[_DRM_STAT_UNLOCKS] );
 
+	/* __HAVE_KERNEL_CTX_SWITCH isn't used by any of the drm
+	 * modules in the DRI cvs tree, but it is required by the
+	 * Sparc driver.
+	 */
+#if __HAVE_KERNEL_CTX_SWITCH
+	/* We no longer really hold it, but if we are the next
+	 * agent to request it then we should just be able to
+	 * take it immediately and not eat the ioctl.
+	 */
+	dev->lock.filp = 0;
+	{
+		__volatile__ unsigned int *plock = &dev->lock.hw_lock->lock;
+		unsigned int old, new, prev, ctx;
+
+		ctx = lock.context;
+		do {
+			old  = *plock;
+			new  = ctx;
+			prev = cmpxchg(plock, old, new);
+		} while (prev != old);
+	}
+	wake_up_interruptible(&dev->lock.lock_queue);
+#else
 	DRM(lock_transfer)( dev, &dev->lock.hw_lock->lock,
 			    DRM_KERNEL_CONTEXT );
 #if __HAVE_DMA_SCHEDULE
@@ -1149,8 +1189,9 @@ int DRM(unlock)( struct inode *inode, struct file *filp,
 
 	if ( DRM(lock_free)( dev, &dev->lock.hw_lock->lock,
 			     DRM_KERNEL_CONTEXT ) ) {
-	   DRM_ERROR( "\n" );
+		DRM_ERROR( "\n" );
 	}
+#endif /* !__HAVE_KERNEL_CTX_SWITCH */
 
 	unblock_all_signals();
 	return 0;
-- 
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