[PATCH 2/2] drm/xe: Init MCR before any mcr register read

[Lucas De Marchi]

On Thu, Aug 08, 2024 at 11:32:51AM GMT, Tejas Upadhyay wrote:
>enable host l2 RAM is example where MCR register is
>getting read before fully MCR init is done. Lets move
>MCR init early and merge early mcr init into main MCR
>init.
>
>Cc: Lucas De Marchi <lucas.demarchi at intel.com>
>Signed-off-by: Tejas Upadhyay <tejas.upadhyay at intel.com>
>---
> drivers/gpu/drm/xe/xe_gt.c     |  3 +--
> drivers/gpu/drm/xe/xe_gt_mcr.c | 21 +++++----------------
> drivers/gpu/drm/xe/xe_gt_mcr.h |  1 -
> 3 files changed, 6 insertions(+), 19 deletions(-)
>
>diff --git a/drivers/gpu/drm/xe/xe_gt.c b/drivers/gpu/drm/xe/xe_gt.c
>index c6296dc8897f..e2e3a1eabde8 100644
>--- a/drivers/gpu/drm/xe/xe_gt.c
>+++ b/drivers/gpu/drm/xe/xe_gt.c
>@@ -555,7 +555,7 @@ int xe_gt_init_hwconfig(struct xe_gt *gt)
> 	if (err)
> 		goto out;
>
>-	xe_gt_mcr_init_early(gt);
>+	xe_gt_mcr_init(gt);
> 	xe_pat_init(gt);
> 	xe_gt_enable_host_l2_vram(gt);
>
>@@ -568,7 +568,6 @@ int xe_gt_init_hwconfig(struct xe_gt *gt)
> 		goto out_fw;
>
> 	xe_gt_topology_init(gt);
>-	xe_gt_mcr_init(gt);

how are you going to init mcr without topology being initialized? That
won't work. I was actually thinking the opposite move:
xe_gt_enable_host_l2_vram() should be after xe_gt_mcr_init()... didn't
realize we had the whole guc load in between, I think that that would
still work for WA 16023588340, but CC Matt Auld.

Lucas De Marchi

>
> out_fw:
> 	xe_force_wake_put(gt_to_fw(gt), XE_FW_GT);
>diff --git a/drivers/gpu/drm/xe/xe_gt_mcr.c b/drivers/gpu/drm/xe/xe_gt_mcr.c
>index 6d948a469126..9c4c4a627bc4 100644
>--- a/drivers/gpu/drm/xe/xe_gt_mcr.c
>+++ b/drivers/gpu/drm/xe/xe_gt_mcr.c
>@@ -375,22 +375,6 @@ static const struct {
> 	[IMPLICIT_STEERING] = { "IMPLICIT", NULL },
> };
>
>-/**
>- * xe_gt_mcr_init_early - Early initialization of the MCR support
>- * @gt: GT structure
>- *
>- * Perform early software only initialization of the MCR lock to allow
>- * the synchronization on accessing the STEER_SEMAPHORE register and
>- * use the xe_gt_mcr_multicast_write() function.
>- */
>-void xe_gt_mcr_init_early(struct xe_gt *gt)
>-{
>-	BUILD_BUG_ON(IMPLICIT_STEERING + 1 != NUM_STEERING_TYPES);
>-	BUILD_BUG_ON(ARRAY_SIZE(xe_steering_types) != NUM_STEERING_TYPES);
>-
>-	spin_lock_init(&gt->mcr_lock);
>-}
>-
> /**
>  * xe_gt_mcr_init - Normal initialization of the MCR support
>  * @gt: GT structure
>@@ -401,9 +385,14 @@ void xe_gt_mcr_init(struct xe_gt *gt)
> {
> 	struct xe_device *xe = gt_to_xe(gt);
>
>+	BUILD_BUG_ON(IMPLICIT_STEERING + 1 != NUM_STEERING_TYPES);
>+	BUILD_BUG_ON(ARRAY_SIZE(xe_steering_types) != NUM_STEERING_TYPES);
>+
> 	if (IS_SRIOV_VF(xe))
> 		return;
>
>+	spin_lock_init(&gt->mcr_lock);
>+
> 	if (gt->info.type == XE_GT_TYPE_MEDIA) {
> 		drm_WARN_ON(&xe->drm, MEDIA_VER(xe) < 13);
>
>diff --git a/drivers/gpu/drm/xe/xe_gt_mcr.h b/drivers/gpu/drm/xe/xe_gt_mcr.h
>index 8d119a0d5493..e7d03e001a49 100644
>--- a/drivers/gpu/drm/xe/xe_gt_mcr.h
>+++ b/drivers/gpu/drm/xe/xe_gt_mcr.h
>@@ -12,7 +12,6 @@
> struct drm_printer;
> struct xe_gt;
>
>-void xe_gt_mcr_init_early(struct xe_gt *gt);
> void xe_gt_mcr_init(struct xe_gt *gt);
>
> void xe_gt_mcr_set_implicit_defaults(struct xe_gt *gt);
>-- 
>2.25.1
>