2 files changed, 54 insertions, 7 deletions

diff --git a/drivers/char/drm/via_dma.c b/drivers/char/drm/via_dma.c
index 94baec692b57..7a339dba6a69 100644
--- a/drivers/char/drm/via_dma.c
+++ b/drivers/char/drm/via_dma.c
@@ -126,6 +126,8 @@ via_cmdbuf_wait(drm_via_private_t * dev_priv, unsigned int size)
                              hw_addr, cur_addr, next_addr);
                         return -1;
                 }
+                if  ((cur_addr < hw_addr) && (next_addr >= hw_addr))
+                        msleep(1);
         } while ((cur_addr < hw_addr) && (next_addr >= hw_addr));
         return 0;
 }
@@ -416,27 +418,50 @@ static int via_hook_segment(drm_via_private_t * dev_priv,
         int paused, count;
         volatile uint32_t *paused_at = dev_priv->last_pause_ptr;
         uint32_t reader,ptr;
+        uint32_t diff;
 
         paused = 0;
         via_flush_write_combine();
         (void) *(volatile uint32_t *)(via_get_dma(dev_priv) -1);
+
         *paused_at = pause_addr_lo;
         via_flush_write_combine();
         (void) *paused_at;
+
         reader = *(dev_priv->hw_addr_ptr);
         ptr = ((volatile char *)paused_at - dev_priv->dma_ptr) +
                 dev_priv->dma_offset + (uint32_t) dev_priv->agpAddr + 4;
+
         dev_priv->last_pause_ptr = via_get_dma(dev_priv) - 1;
 
-        if ((ptr - reader) <= dev_priv->dma_diff ) {
-                count = 10000000;
-                while (!(paused = (VIA_READ(0x41c) & 0x80000000)) && count--);
+        /*
+         * If there is a possibility that the command reader will 
+         * miss the new pause address and pause on the old one,
+         * In that case we need to program the new start address
+         * using PCI.
+         */
+
+        diff = (uint32_t) (ptr - reader) - dev_priv->dma_diff;
+        count = 10000000;
+        while(diff == 0 && count--) {
+                paused = (VIA_READ(0x41c) & 0x80000000);
+                if (paused) 
+                        break;
+                reader = *(dev_priv->hw_addr_ptr);
+                diff = (uint32_t) (ptr - reader) - dev_priv->dma_diff;
         }
 
+        paused = VIA_READ(0x41c) & 0x80000000;
+
         if (paused && !no_pci_fire) {
                 reader = *(dev_priv->hw_addr_ptr);
-                if ((ptr - reader) == dev_priv->dma_diff) {
-
+                diff = (uint32_t) (ptr - reader) - dev_priv->dma_diff;
+                diff &= (dev_priv->dma_high - 1);
+                if (diff != 0 && diff < (dev_priv->dma_high >> 1)) {
+                        DRM_ERROR("Paused at incorrect address. "
+                                  "0x%08x, 0x%08x 0x%08x\n",
+                                  ptr, reader, dev_priv->dma_diff);
+                } else if (diff == 0) {
                         /*
                          * There is a concern that these writes may stall the PCI bus
                          * if the GPU is not idle. However, idling the GPU first
@@ -577,6 +602,7 @@ static void via_cmdbuf_jump(drm_via_private_t * dev_priv)
         uint32_t pause_addr_lo, pause_addr_hi;
         uint32_t jump_addr_lo, jump_addr_hi;
         volatile uint32_t *last_pause_ptr;
+        uint32_t dma_low_save1, dma_low_save2;
 
         agp_base = dev_priv->dma_offset + (uint32_t) dev_priv->agpAddr;
         via_align_cmd(dev_priv, HC_HAGPBpID_JUMP, 0, &jump_addr_hi,
@@ -603,8 +629,29 @@ static void via_cmdbuf_jump(drm_via_private_t * dev_priv)
                       &pause_addr_lo, 0);
 
         *last_pause_ptr = pause_addr_lo;
+        dma_low_save1 = dev_priv->dma_low;
 
-        via_hook_segment( dev_priv, jump_addr_hi, jump_addr_lo, 0);
+        /*
+         * Now, set a trap that will pause the regulator if it tries to rerun the old
+         * command buffer. (Which may happen if via_hook_segment detecs a command regulator pause
+         * and reissues the jump command over PCI, while the regulator has already taken the jump
+         * and actually paused at the current buffer end).
+         * There appears to be no other way to detect this condition, since the hw_addr_pointer
+         * does not seem to get updated immediately when a jump occurs.
+         */
+
+        last_pause_ptr =
+                via_align_cmd(dev_priv, HC_HAGPBpID_PAUSE, 0, &pause_addr_hi,
+                              &pause_addr_lo, 0) - 1;
+        via_align_cmd(dev_priv, HC_HAGPBpID_PAUSE, 0, &pause_addr_hi,
+                      &pause_addr_lo, 0);
+        *last_pause_ptr = pause_addr_lo;
+
+        dma_low_save2 = dev_priv->dma_low;
+        dev_priv->dma_low = dma_low_save1;
+        via_hook_segment(dev_priv, jump_addr_hi, jump_addr_lo, 0);
+        dev_priv->dma_low = dma_low_save2;
+        via_hook_segment(dev_priv, pause_addr_hi, pause_addr_lo, 0);
 }
 
 
diff --git a/drivers/char/drm/via_dmablit.c b/drivers/char/drm/via_dmablit.c
index 33c5197b73c4..409e00afdd07 100644
--- a/drivers/char/drm/via_dmablit.c
+++ b/drivers/char/drm/via_dmablit.c
@@ -603,7 +603,7 @@ via_build_sg_info(struct drm_device *dev, drm_via_sg_info_t *vsg, drm_via_dmabli
          * (Not a big limitation anyway.)
          */
 
-        if ((xfer->mem_stride - xfer->line_length) >= PAGE_SIZE) {
+        if ((xfer->mem_stride - xfer->line_length) > 2*PAGE_SIZE) {
                 DRM_ERROR("Too large system memory stride. Stride: %d, "
                           "Length: %d\n", xfer->mem_stride, xfer->line_length);
                 return -EINVAL;