[PATCH 1/2] drm/i915: Limit the ioremap of the PCI bar to the registers

[Chris Wilson <chris@chris-wilson.co.uk>]

In the future we may like to experiment with using a WC map of the GTT
portion. However, that will conflict with i915.ko mapping the entire bar
as UC in order to access the GPU registers. Instead we can shrink the
register ioremap to only map the register block.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_dma.c |   14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index ee9fe72..18bb48b 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -1460,7 +1460,7 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
 {
 	struct drm_i915_private *dev_priv;
 	struct intel_device_info *info;
-	int ret = 0, mmio_bar;
+	int ret = 0, mmio_bar, mmio_size;
 	uint32_t aperture_size;
 
 	info = (struct intel_device_info *) flags;
@@ -1524,8 +1524,18 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
 	if (IS_BROADWATER(dev) || IS_CRESTLINE(dev))
 		dma_set_coherent_mask(&dev->pdev->dev, DMA_BIT_MASK(32));
 
+	/* Restrict iomap to avoid clobbering the GTT which we want WC mapped.
+	 * Do not attempt to map the whole BAR!
+	 */
 	mmio_bar = IS_GEN2(dev) ? 1 : 0;
-	dev_priv->regs = pci_iomap(dev->pdev, mmio_bar, 0);
+	if (info->gen < 3)
+		mmio_size = 64*1024;
+	else if (info->gen < 5)
+		mmio_size = 512*1024;
+	else
+		mmio_size = 2*1024*1024;
+
+	dev_priv->regs = pci_iomap(dev->pdev, mmio_bar, mmio_size);
 	if (!dev_priv->regs) {
 		DRM_ERROR("failed to map registers\n");
 		ret = -EIO;
-- 
1.7.10.4