[Intel-xe] [PATCH 1/2] RFC drm/xe: Disable ctb communication

[Ceraolo Spurio, Daniele]

On 8/22/2023 10:09 PM, Riana Tauro wrote:
> During Runtime suspend, GuC is reset for both D0->D3hot/D3Cold
> transistions. It is not necessary for GuC to reset for D0 -> D3hot,
> only enable/disable ctb communication.
>
> Modify the existing ct disable function to send a request
> to disable ct communication if firmware is running.
> Add a function to disable guc communication.
>
> Signed-off-by: Riana Tauro <riana.tauro at intel.com>
> ---
>   drivers/gpu/drm/xe/xe_guc.c    | 15 +++++++++++++++
>   drivers/gpu/drm/xe/xe_guc.h    |  1 +
>   drivers/gpu/drm/xe/xe_guc_ct.c | 11 ++++++++++-
>   drivers/gpu/drm/xe/xe_guc_ct.h |  2 +-
>   4 files changed, 27 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/xe/xe_guc.c b/drivers/gpu/drm/xe/xe_guc.c
> index 2493c5859948..3e4c00bee6bf 100644
> --- a/drivers/gpu/drm/xe/xe_guc.c
> +++ b/drivers/gpu/drm/xe/xe_guc.c
> @@ -557,6 +557,21 @@ int xe_guc_enable_communication(struct xe_guc *guc)
>   	return 0;
>   }
>   
> +int xe_guc_disable_communication(struct xe_guc *guc)
> +{
> +	int err;
> +	struct xe_guc_ct *ct = &guc->ct;
> +
> +	err = xe_guc_ct_disable(ct);
> +	if (err)
> +		return err;
> +
> +	/* Check for messages received during/after the CT disable */
> +	guc_handle_mmio_msg(guc);
> +
> +	return 0;
> +}
> +
>   int xe_guc_suspend(struct xe_guc *guc)
>   {
>   	int ret;
> diff --git a/drivers/gpu/drm/xe/xe_guc.h b/drivers/gpu/drm/xe/xe_guc.h
> index 3addd8fc674a..18cf5d02eea7 100644
> --- a/drivers/gpu/drm/xe/xe_guc.h
> +++ b/drivers/gpu/drm/xe/xe_guc.h
> @@ -18,6 +18,7 @@ int xe_guc_post_load_init(struct xe_guc *guc);
>   int xe_guc_reset(struct xe_guc *guc);
>   int xe_guc_upload(struct xe_guc *guc);
>   int xe_guc_min_load_for_hwconfig(struct xe_guc *guc);
> +int xe_guc_disable_communication(struct xe_guc *guc);
>   int xe_guc_enable_communication(struct xe_guc *guc);
>   int xe_guc_suspend(struct xe_guc *guc);
>   void xe_guc_notify(struct xe_guc *guc);
> diff --git a/drivers/gpu/drm/xe/xe_guc_ct.c b/drivers/gpu/drm/xe/xe_guc_ct.c
> index 59136b6a7c6f..64c2029b2752 100644
> --- a/drivers/gpu/drm/xe/xe_guc_ct.c
> +++ b/drivers/gpu/drm/xe/xe_guc_ct.c
> @@ -21,6 +21,7 @@
>   #include "xe_map.h"
>   #include "xe_pm.h"
>   #include "xe_trace.h"
> +#include "xe_uc_fw.h"
>   
>   /* Used when a CT send wants to block and / or receive data */
>   struct g2h_fence {
> @@ -319,15 +320,23 @@ int xe_guc_ct_enable(struct xe_guc_ct *ct)
>   	return err;
>   }
>   
> -void xe_guc_ct_disable(struct xe_guc_ct *ct)
> +int xe_guc_ct_disable(struct xe_guc_ct *ct)
>   {
> +	struct xe_guc *guc = ct_to_guc(ct);
> +	int ret = 0;
> +
>   	mutex_lock(&ct->lock); /* Serialise dequeue_one_g2h() */
>   	spin_lock_irq(&ct->fast_lock); /* Serialise CT fast-path */
>   	ct->enabled = false; /* Finally disable CT communication */
>   	spin_unlock_irq(&ct->fast_lock);
>   	mutex_unlock(&ct->lock);
>   
> +	if (xe_uc_fw_is_running(&guc->fw))
> +		ret = guc_ct_control_toggle(ct, false);

Note that if we're not killing the GuC there isn't really a need to 
unregister and re-register the CTBs, we could just set ct->enabled = 
false on suspend and flip it back to ct->enabled = true on resume.

Daniele

> +
>   	xa_destroy(&ct->fence_lookup);
> +
> +	return ret;
>   }
>   
>   static bool h2g_has_room(struct xe_guc_ct *ct, u32 cmd_len)
> diff --git a/drivers/gpu/drm/xe/xe_guc_ct.h b/drivers/gpu/drm/xe/xe_guc_ct.h
> index f15f8a4857e0..1ad150c19ae3 100644
> --- a/drivers/gpu/drm/xe/xe_guc_ct.h
> +++ b/drivers/gpu/drm/xe/xe_guc_ct.h
> @@ -12,7 +12,7 @@ struct drm_printer;
>   
>   int xe_guc_ct_init(struct xe_guc_ct *ct);
>   int xe_guc_ct_enable(struct xe_guc_ct *ct);
> -void xe_guc_ct_disable(struct xe_guc_ct *ct);
> +int xe_guc_ct_disable(struct xe_guc_ct *ct);
>   void xe_guc_ct_fast_path(struct xe_guc_ct *ct);
>   
>   struct xe_guc_ct_snapshot *