vblank.c

Mesa is an open-source implementation of the OpenGL specification - a system for rendering interacti

/* -*- mode: c; c-basic-offset: 3 -*- */
/*
 * (c) Copyright IBM Corporation 2002
 * All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * on the rights to use, copy, modify, merge, publish, distribute, sub
 * license, and/or sell copies of the Software, and to permit persons to whom
 * the Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.  IN NO EVENT SHALL
 * VA LINUX SYSTEM, IBM AND/OR THEIR SUPPLIERS BE LIABLE FOR ANY CLAIM,
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
 * USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * Authors:
 *    Ian Romanick <[e-mail]>
 */
/* $XFree86:$ */

#include "glheader.h"
#include "xf86drm.h"
#include "mtypes.h"
#include "macros.h"
#include "dd.h"
#include "vblank.h"
#include "xmlpool.h"

static unsigned int msc_to_vblank(__DRIdrawablePrivate * dPriv, int64_t msc)
{
   return (unsigned int)(msc - dPriv->msc_base + dPriv->vblank_base);
}

static int64_t vblank_to_msc(__DRIdrawablePrivate * dPriv, unsigned int vblank)
{
   return (int64_t)(vblank - dPriv->vblank_base + dPriv->msc_base);
}


/****************************************************************************/
/**
 * Get the current MSC refresh counter.
 *
 * Stores the 64-bit count of vertical refreshes since some (arbitrary)
 * point in time in \c count.  Unless the value wraps around, which it
 * may, it will never decrease for a given drawable.
 *
 * \warning This function is called from \c glXGetVideoSyncSGI, which expects
 * a \c count of type \c unsigned (32-bit), and \c glXGetSyncValuesOML, which 
 * expects a \c count of type \c int64_t (signed 64-bit).  The kernel ioctl 
 * currently always returns a \c sequence of type \c unsigned.
 *
 * \param priv   Pointer to the DRI screen private struct.
 * \param dPriv  Pointer to the DRI drawable private struct
 * \param count  Storage to hold MSC counter.
 * \return       Zero is returned on success.  A negative errno value
 *               is returned on failure.
 */
int driDrawableGetMSC32( __DRIscreenPrivate * priv,
			 __DRIdrawablePrivate * dPriv,
			 int64_t * count)
{
   drmVBlank vbl;
   int ret;

   /* Don't wait for anything.  Just get the current refresh count. */

   vbl.request.type = DRM_VBLANK_RELATIVE;
   vbl.request.sequence = 0;
   if ( dPriv && dPriv->vblFlags & VBLANK_FLAG_SECONDARY )
      vbl.request.type |= DRM_VBLANK_SECONDARY;

   ret = drmWaitVBlank( priv->fd, &vbl );

   if (dPriv) {
      *count = vblank_to_msc(dPriv, vbl.reply.sequence);
   } else {
      /* Old driver (no knowledge of drawable MSC callback) */
      *count = vbl.reply.sequence;
   }

   return ret;
}

/****************************************************************************/
/**
 * Wait for a specified refresh count.  This implements most of the
 * functionality of \c glXWaitForMscOML from the GLX_OML_sync_control spec.
 * Waits for the \c target_msc refresh.  If that has already passed, it
 * waits until \f$(MSC \bmod divisor)\f$ is equal to \c remainder.  If 
 * \c target_msc is 0, use the behavior of glXWaitVideoSyncSGI(), which
 * omits the initial check against a target MSC value.
 * 
 * This function is actually something of a hack.  The problem is that, at
 * the time of this writing, none of the existing DRM modules support an
 * ioctl that returns a 64-bit count (at least not on 32-bit platforms).
 * However, this function exists to support a GLX function that requires
 * the use of 64-bit counts.  As such, there is a little bit of ugly
 * hackery at the end of this function to make the 32-bit count act like
 * a 64-bit count.  There are still some cases where this will break, but
 * I believe it catches the most common cases.
 *
 * The real solution is to provide an ioctl that uses a 64-bit count.
 *
 * \param dpy         Pointer to the \c Display.
 * \param priv        Pointer to the DRI drawable private.
 * \param target_msc  Desired refresh count to wait for.  A value of 0
 *                    means to use the glXWaitVideoSyncSGI() behavior.
 * \param divisor     MSC divisor if \c target_msc is already reached.
 * \param remainder   Desired MSC remainder if \c target_msc is already
 *                    reached.
 * \param msc         Buffer to hold MSC when done waiting.
 *
 * \return            Zero on success or \c GLX_BAD_CONTEXT on failure.
 */

int driWaitForMSC32( __DRIdrawablePrivate *priv,
		     int64_t target_msc, int64_t divisor, int64_t remainder,
		     int64_t * msc )
{
   drmVBlank vbl;


   if ( divisor != 0 ) {
      unsigned int target = (unsigned int)target_msc;
      unsigned int next = target;
      unsigned int r;
      int dont_wait = (target_msc == 0);

      do {
         /* dont_wait means we're using the glXWaitVideoSyncSGI() behavior.
          * The first time around, just get the current count and proceed 
          * to the test for (MSC % divisor) == remainder.
          */
         vbl.request.type = dont_wait ? DRM_VBLANK_RELATIVE :
                                        DRM_VBLANK_ABSOLUTE;
         vbl.request.sequence = next ? msc_to_vblank(priv, next) : 0;
	 if ( priv->vblFlags & VBLANK_FLAG_SECONDARY )
	    vbl.request.type |= DRM_VBLANK_SECONDARY;

	 if ( drmWaitVBlank( priv->driScreenPriv->fd, &vbl ) != 0 ) {
	    /* FIXME: This doesn't seem like the right thing to return here.
	     */
	    return GLX_BAD_CONTEXT;
	 }

	 *msc = vblank_to_msc(priv, vbl.reply.sequence);

         dont_wait = 0;
         if (target_msc != 0 && *msc == target)
            break;

         /* Assuming the wait-done test fails, the next refresh to wait for
          * will be one that satisfies (MSC % divisor) == remainder.  The
          * value (MSC - (MSC % divisor) + remainder) is the refresh value 
          * closest to the current value that would satisfy the equation.  
          * If this refresh has already happened, we add divisor to obtain 
          * the next refresh after the current one that will satisfy it.
          */
         r = (*msc % (unsigned int)divisor);
         next = (*msc - r + (unsigned int)remainder);
         if (next <= *msc) next += (unsigned int)divisor;

      } while ( r != (unsigned int)remainder );
   }
   else {
      /* If the \c divisor is zero, just wait until the MSC is greater
       * than or equal to \c target_msc.
       */

      vbl.request.type = DRM_VBLANK_ABSOLUTE;
      vbl.request.sequence = target_msc ? msc_to_vblank(priv, target_msc) : 0;

      if ( priv->vblFlags & VBLANK_FLAG_SECONDARY )
	 vbl.request.type |= DRM_VBLANK_SECONDARY;

      if ( drmWaitVBlank( priv->driScreenPriv->fd, &vbl ) != 0 ) {
	 /* FIXME: This doesn't seem like the right thing to return here.
	  */
	 return GLX_BAD_CONTEXT;
      }
   }

   *msc = vblank_to_msc(priv, vbl.reply.sequence);

   if ( *msc < target_msc ) {
      *msc += 0x0000000100000000LL;
   }

   return 0;
}


/****************************************************************************/
/**
 * Gets a set of default vertical-blank-wait flags based on the internal GLX
 * API version and several configuration options.
 */

GLuint driGetDefaultVBlankFlags( const driOptionCache *optionCache )
{
   GLuint  flags = VBLANK_FLAG_INTERVAL;
   int vblank_mode;


   if ( driCheckOption( optionCache, "vblank_mode", DRI_ENUM ) )
      vblank_mode = driQueryOptioni( optionCache, "vblank_mode" );
   else
      vblank_mode = DRI_CONF_VBLANK_DEF_INTERVAL_1;

   switch (vblank_mode) {
   case DRI_CONF_VBLANK_NEVER:
      flags = 0;
      break;
   case DRI_CONF_VBLANK_DEF_INTERVAL_0:
      break;
   case DRI_CONF_VBLANK_DEF_INTERVAL_1:
      flags |= VBLANK_FLAG_THROTTLE;
      break;
   case DRI_CONF_VBLANK_ALWAYS_SYNC:
      flags |= VBLANK_FLAG_SYNC;
      break;
   }

   return flags;
}


/****************************************************************************/
/**
 * Wrapper to call \c drmWaitVBlank.  The main purpose of this function is to
 * wrap the error message logging.  The error message should only be logged
 * the first time the \c drmWaitVBlank fails.  If \c drmWaitVBlank is
 * successful, \c vbl_seq will be set the sequence value in the reply.
 *
 * \param vbl      Pointer to drmVBlank packet desribing how to wait.
 * \param vbl_seq  Location to store the current refresh counter.
 * \param fd       File descriptor use to call into the DRM.
 * \return         Zero on success or -1 on failure.
 */

static int do_wait( drmVBlank * vbl, GLuint * vbl_seq, int fd )
{
   int   ret;


   ret = drmWaitVBlank( fd, vbl );
   if ( ret != 0 ) {
      static GLboolean first_time = GL_TRUE;

      if ( first_time ) {
	 fprintf(stderr, 
		 "%s: drmWaitVBlank returned %d, IRQs don't seem to be"
		 " working correctly.\nTry adjusting the vblank_mode"
		 " configuration parameter.\n", __FUNCTION__, ret);
	 first_time = GL_FALSE;
      }

      return -1;
   }

   *vbl_seq = vbl->reply.sequence;
   return 0;
}


/****************************************************************************/
/**
 * Returns the default swap interval of the given drawable.
 */

static unsigned
driGetDefaultVBlankInterval( const  __DRIdrawablePrivate *priv )
{
   if ( (priv->vblFlags & (VBLANK_FLAG_THROTTLE | VBLANK_FLAG_SYNC)) != 0 ) {
      return 1;
   }
   else {
      return 0;
   }
}


/****************************************************************************/
/**
 * Sets the default swap interval when the drawable is first bound to a
 * direct rendering context.
 */

void driDrawableInitVBlank( __DRIdrawablePrivate *priv )
{
   if ( priv->swap_interval == (unsigned)-1 &&
	!( priv->vblFlags & VBLANK_FLAG_NO_IRQ ) ) {
      /* Get current vertical blank sequence */
      drmVBlank vbl;
 
      vbl.request.type = DRM_VBLANK_RELATIVE;
      if ( priv->vblFlags & VBLANK_FLAG_SECONDARY )
 	 vbl.request.type |= DRM_VBLANK_SECONDARY;
      vbl.request.sequence = 0;
      do_wait( &vbl, &priv->vblSeq, priv->driScreenPriv->fd );
      priv->vblank_base = priv->vblSeq;

      priv->swap_interval = driGetDefaultVBlankInterval( priv );
   }
}


/****************************************************************************/
/**
 * Returns the current swap interval of the given drawable.
 */

unsigned
driGetVBlankInterval( const  __DRIdrawablePrivate *priv )
{
   if ( (priv->vblFlags & VBLANK_FLAG_INTERVAL) != 0 ) {
      /* this must have been initialized when the drawable was first bound
       * to a direct rendering context. */
      assert ( priv->swap_interval != (unsigned)-1 );

      return priv->swap_interval;
   }
   else 
      return driGetDefaultVBlankInterval( priv );
}


/****************************************************************************/
/**
 * Returns the current vertical blank sequence number of the given drawable.
 */

void
driGetCurrentVBlank( __DRIdrawablePrivate *priv )
{
   drmVBlank vbl;

   vbl.request.type = DRM_VBLANK_RELATIVE;
   if ( priv->vblFlags & VBLANK_FLAG_SECONDARY ) {
      vbl.request.type |= DRM_VBLANK_SECONDARY;
   }
   vbl.request.sequence = 0;

   (void) do_wait( &vbl, &priv->vblSeq, priv->driScreenPriv->fd );
}


/****************************************************************************/
/**
 * Waits for the vertical blank for use with glXSwapBuffers.
 * 
 * \param missed_deadline  Set to \c GL_TRUE if the MSC after waiting is later
 *                 than the "target" based on \c priv->vblFlags.  The idea is
 *                 that if \c missed_deadline is set, then the application is
 *                 not achieving its desired framerate.
 * \return         Zero on success, -1 on error.
 */

int
driWaitForVBlank( __DRIdrawablePrivate *priv, GLboolean * missed_deadline )
{
   drmVBlank vbl;
   unsigned   original_seq;
   unsigned   deadline;
   unsigned   interval;
   unsigned   diff;

   *missed_deadline = GL_FALSE;
   if ( (priv->vblFlags & (VBLANK_FLAG_INTERVAL |
			   VBLANK_FLAG_THROTTLE |
			   VBLANK_FLAG_SYNC)) == 0 ||
	(priv->vblFlags & VBLANK_FLAG_NO_IRQ) != 0 ) {
      return 0;
   }


   /* VBLANK_FLAG_SYNC means to wait for at least one vertical blank.  If
    * that flag is not set, do a fake wait for zero vertical blanking
    * periods so that we can get the current MSC.
    *
    * VBLANK_FLAG_INTERVAL and VBLANK_FLAG_THROTTLE mean to wait for at
    * least one vertical blank since the last wait.  Since do_wait modifies
    * priv->vblSeq, we have to save the original value of priv->vblSeq for the
    * VBLANK_FLAG_INTERVAL / VBLANK_FLAG_THROTTLE calculation later.
    */

   original_seq = priv->vblSeq;
   interval = driGetVBlankInterval(priv);
   deadline = original_seq + interval;

   vbl.request.type = DRM_VBLANK_RELATIVE;
   if ( priv->vblFlags & VBLANK_FLAG_SECONDARY ) {
      vbl.request.type |= DRM_VBLANK_SECONDARY;
   }
   vbl.request.sequence = ((priv->vblFlags & VBLANK_FLAG_SYNC) != 0) ? 1 : 0;

   if ( do_wait( & vbl, &priv->vblSeq, priv->driScreenPriv->fd ) != 0 ) {
      return -1;
   }

   diff = priv->vblSeq - deadline;

   /* No need to wait again if we've already reached the target */
   if (diff <= (1 << 23)) {
      *missed_deadline = (priv->vblFlags & VBLANK_FLAG_SYNC) ? (diff > 0) :
			 GL_TRUE;
      return 0;
   }

   /* Wait until the target vertical blank. */
   vbl.request.type = DRM_VBLANK_ABSOLUTE;
   if ( priv->vblFlags & VBLANK_FLAG_SECONDARY ) {
      vbl.request.type |= DRM_VBLANK_SECONDARY;
   }
   vbl.request.sequence = deadline;

   if ( do_wait( & vbl, &priv->vblSeq, priv->driScreenPriv->fd ) != 0 ) {
      return -1;
   }

   diff = priv->vblSeq - deadline;
   *missed_deadline = diff > 0 && diff <= (1 << 23);

   return 0;
}