Hi Wilson,
Thanks for bring up this. This is a necessary step during the booting to allow the ME communicate with display but we don't need turn off for unload actually.
Best regards,
Sean
-----Original Message-----
From: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Sent: Thursday, December 10, 2020 12:45 AM
To: Huang, Sean Z <sean.z.huang@xxxxxxxxx>; Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
Subject: Re: [RFC-v4 02/21] drm/i915/pxp: set KCR reg init during the boot time
Quoting Huang, Sean Z (2020-12-10 07:24:16)
> Set the KCR init during the boot time, which is required by hardware,
> to allow us doing further protection operation such as sending
> commands to GPU or TEE.
>
> Signed-off-by: Huang, Sean Z <sean.z.huang@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/pxp/intel_pxp.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/pxp/intel_pxp.c
> b/drivers/gpu/drm/i915/pxp/intel_pxp.c
> index ba43b2c923c7..c4815950567d 100644
> --- a/drivers/gpu/drm/i915/pxp/intel_pxp.c
> +++ b/drivers/gpu/drm/i915/pxp/intel_pxp.c
> @@ -6,6 +6,12 @@
> #include "intel_pxp.h"
> #include "intel_pxp_context.h"
>
> +/* KCR register definitions */
> +#define KCR_INIT _MMIO(0x320f0)
> +#define KCR_INIT_MASK_SHIFT (16)
> +/* Setting KCR Init bit is required after system boot */ #define
> +KCR_INIT_ALLOW_DISPLAY_ME_WRITES (BIT(14) | (BIT(14) <<
> +KCR_INIT_MASK_SHIFT))
> +
> int intel_pxp_init(struct intel_pxp *pxp) {
> struct intel_gt *gt = container_of(pxp, struct intel_gt, pxp);
> @@ -16,6 +22,8 @@ int intel_pxp_init(struct intel_pxp *pxp)
>
> intel_pxp_ctx_init(&pxp->ctx);
>
> + intel_uncore_write(gt->uncore, KCR_INIT,
> + KCR_INIT_ALLOW_DISPLAY_ME_WRITES);
So this looks dangerous to leave enabled after driver unload?
-Chris
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