Re: [PATCH] drm/i915: Provide a parameter to disable loading

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, Jan 16, 2014 at 04:33:26PM +0000, Damien Lespiau wrote:
> It can be handy at times to forbid i915 from loading at startup to
> modprobe it later.

modprobe.blacklist=i915

> 
> In particular, when trying to debug a problem that occurs at startup,
> it's usually easier to boot into a working machine and modprobe the
> driver at a more convenient time.
> 
> Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 61fb9fc..d80e47e 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -38,6 +38,12 @@
>  #include <linux/module.h>
>  #include <drm/drm_crtc_helper.h>
>  
> +static int i915_fail __read_mostly = 0;
> +module_param_named(fail, i915_fail, int, 0400);
> +MODULE_PARM_DESC(fail,
> +		"Allow a user to skip loading the i915 driver, "
> +		"0=load i915 as usual [default], 1=don't load");
> +
>  static int i915_modeset __read_mostly = -1;
>  module_param_named(modeset, i915_modeset, int, 0400);
>  MODULE_PARM_DESC(modeset,
> @@ -823,6 +829,11 @@ static int i915_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
>  	struct intel_device_info *intel_info =
>  		(struct intel_device_info *) ent->driver_data;
>  
> +	if (i915_fail) {
> +		DRM_INFO("i915 disabled by module parameter\n");
> +		return -ENODEV;
> +	}
> +
>  	if (IS_PRELIMINARY_HW(intel_info) && !i915_preliminary_hw_support) {
>  		DRM_INFO("This hardware requires preliminary hardware support.\n"
>  			 "See CONFIG_DRM_I915_PRELIMINARY_HW_SUPPORT, and/or modparam preliminary_hw_support\n");
> -- 
> 1.8.3.1
> 
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-- 
Ville Syrjälä
Intel OTC