[Intel-gfx] [PATCH v2] drm/i915: Handle PipeC fused off on GEN7+

[Damien Lespiau]

On Wed, Jan 13, 2016 at 04:46:43PM +0200, Gabriel Feceoru wrote:
> Starting with Gen7 (IVB) Display PipeC can be fused off on some production
> parts. When disabled, display hardware will prevent the pipe C register bit
> from being set to 1.
> 
> Fixed by adjusting pipe_count to reflect this.

The title is misleading, it's really just IVB/HSW/BDW not gen7+

You want to add the changelog of the patch in the commit message as
well, eg.

v2: Rename HSW_PIPE_C_DISABLE to IVB_PIPE_C_DISABLE as it already exists
    on ivybridge (Ville)

also, we can get rid of the MMIO access (see below)

-- 
Damien

> Signed-off-by: Gabriel Feceoru <gabriel.feceoru at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_dma.c | 3 +++
>  drivers/gpu/drm/i915/i915_reg.h | 1 +
>  2 files changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> index 44a896c..c3b93e7 100644
> --- a/drivers/gpu/drm/i915/i915_dma.c
> +++ b/drivers/gpu/drm/i915/i915_dma.c
> @@ -813,6 +813,9 @@ static void intel_device_info_runtime_init(struct drm_device *dev)
>  		     !(sfuse_strap & SFUSE_STRAP_FUSE_LOCK))) {
>  			DRM_INFO("Display fused off, disabling\n");
>  			info->num_pipes = 0;
> +		} else if (I915_READ(FUSE_STRAP) & IVB_PIPE_C_DISABLE) {
> +			DRM_INFO("PipeC fused off\n");
> +			info->num_pipes -= 1;


FUSE_STRAP is alreay read above, it's in the fuse_trap variable.

HTH,

-- 
Damien