On Wed, 08 Aug 2018, José Roberto de Souza <jose.souza@xxxxxxxxx> wrote:
> num_pipes is set to 0 if disable_display is set inside
> intel_device_info_runtime_init() but when that happen PCH will
> already be set in intel_detect_pch().
>
> i915_driver_load()
> i915_driver_init_early()
> ...
> intel_detect_pch()
> ...
> ...
> i915_driver_init_hw()
> intel_device_info_runtime_init()
>
> So now setting num_pipes = 0 earlier to avoid this problem.
Okay, this gets confusing. There are other paths in
intel_device_info_runtime_init() that set num_pipes = 0 and depend on
PCH having been detected. :(
>
> Cc: Jani Nikula <jani.nikula@xxxxxxxxx>
> Signed-off-by: José Roberto de Souza <jose.souza@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_drv.c | 5 +++++
> drivers/gpu/drm/i915/intel_device_info.c | 8 ++------
> 2 files changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 9dce55182c3a..7952f5877402 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -917,6 +917,11 @@ static int i915_driver_init_early(struct drm_i915_private *dev_priv,
> if (ret < 0)
> goto err_workqueues;
>
> + if (i915_modparams.disable_display) {
> + DRM_INFO("Display disabled (module parameter)\n");
> + device_info->num_pipes = 0;
> + }
> +
Please look at the function as a whole, and note that this feels like a
random thing to add in the middle. Needs to be stowed away somewhere
deeper.
Overall, I think we need to be more accurate about the relationship of
num_pipes = 0 and PCH_NOP.
BR,
Jani.
> /* This must be called before any calls to HAS_PCH_* */
> intel_detect_pch(dev_priv);
>
> diff --git a/drivers/gpu/drm/i915/intel_device_info.c b/drivers/gpu/drm/i915/intel_device_info.c
> index 0ef0c6448d53..67102b481c8f 100644
> --- a/drivers/gpu/drm/i915/intel_device_info.c
> +++ b/drivers/gpu/drm/i915/intel_device_info.c
> @@ -776,12 +776,8 @@ void intel_device_info_runtime_init(struct intel_device_info *info)
> info->num_sprites[pipe] = 1;
> }
>
> - if (i915_modparams.disable_display) {
> - DRM_INFO("Display disabled (module parameter)\n");
> - info->num_pipes = 0;
> - } else if (info->num_pipes > 0 &&
> - (IS_GEN7(dev_priv) || IS_GEN8(dev_priv)) &&
> - HAS_PCH_SPLIT(dev_priv)) {
> + if (info->num_pipes > 0 && (IS_GEN7(dev_priv) || IS_GEN8(dev_priv)) &&
> + HAS_PCH_SPLIT(dev_priv)) {
> u32 fuse_strap = I915_READ(FUSE_STRAP);
> u32 sfuse_strap = I915_READ(SFUSE_STRAP);
--
Jani Nikula, Intel Open Source Graphics Center
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