[PATCH 2/2] drm/i915: Add dependency on the intel agp module

[Chase Douglas]

On Wed, Apr 7, 2010 at 6:24 AM, Andy Whitcroft <apw at canonical.com> wrote:
> From: Zhenyu Wang <zhenyuw at linux.intel.com>
>
> See http://bugzilla.kernel.org/show_bug.cgi?id=15021
>
> Make sure that the appropriate AGP module is loaded and probed before
> trying to set up the DRM.  The DRM already depends on the AGP core,
> but in this case we know the specific AGP driver we need too, and can
> help users avoid the trap of loading the AGP driver after the DRM
> driver.
>
> Signed-off-by: Zhenyu Wang <zhenyuw at linux.intel.com>
> Signed-off-by: Eric Anholt <eric at anholt.net>
>
> (cherry picked from commit 1f7a6e372e9cb4d749f34c0738d832e6cadb4071 upstream)
> BugLink: http://bugs.launchpad.net/bugs/542251
>
> Signed-off-by: Andy Whitcroft <apw at canonical.com>
> ---
>  drivers/char/agp/intel-agp.c    |   10 ++++++++--
>  drivers/gpu/drm/i915/i915_drv.c |    6 ++++++
>  2 files changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/char/agp/intel-agp.c b/drivers/char/agp/intel-agp.c
> index 4dcfef0..89f5609 100644
> --- a/drivers/char/agp/intel-agp.c
> +++ b/drivers/char/agp/intel-agp.c
> @@ -10,6 +10,9 @@
>  #include <linux/agp_backend.h>
>  #include "agp.h"
>
> +int intel_agp_enabled;
> +EXPORT_SYMBOL(intel_agp_enabled);
> +
>  /*
>  * If we have Intel graphics, we're not going to have anything other than
>  * an Intel IOMMU. So make the correct use of the PCI DMA API contingent
> @@ -2378,7 +2381,7 @@ static int __devinit agp_intel_probe(struct pci_dev *pdev,
>        struct agp_bridge_data *bridge;
>        u8 cap_ptr = 0;
>        struct resource *r;
> -       int i;
> +       int i, err;
>
>        cap_ptr = pci_find_capability(pdev, PCI_CAP_ID_AGP);
>
> @@ -2466,7 +2469,10 @@ static int __devinit agp_intel_probe(struct pci_dev *pdev,
>                                "set gfx device dma mask 36bit failed!\n");
>
>        pci_set_drvdata(pdev, bridge);
> -       return agp_add_bridge(bridge);
> +       err = agp_add_bridge(bridge);
> +       if (!err)
> +               intel_agp_enabled = 1;
> +       return err;
>  }
>
>  static void __devexit agp_intel_remove(struct pci_dev *pdev)
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 4746bfe..f7d7c12 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -49,6 +49,7 @@ unsigned int i915_lvds_downclock = 0;
>  module_param_named(lvds_downclock, i915_lvds_downclock, int, 0400);
>
>  static struct drm_driver driver;
> +extern int intel_agp_enabled;
>
>  #define INTEL_VGA_DEVICE(id, info) {           \
>        .class = PCI_CLASS_DISPLAY_VGA << 8,    \
> @@ -546,6 +547,11 @@ static struct drm_driver driver = {
>
>  static int __init i915_init(void)
>  {
> +       if (!intel_agp_enabled) {
> +               DRM_ERROR("drm/i915 can't work without intel_agp module!\n");
> +               return -ENODEV;
> +       }
> +

What happens here if the agp isn't enabled yet? It seems like the
driver just gives up. How does this help?

>        driver.num_ioctls = i915_max_ioctl;
>
>        i915_gem_shrinker_init();
> --
> 1.7.0

-- Chase