Re: [PATCH v3 6/8] drm/panthor: Support GLB_REQ.STATE field for Mali-G1 GPUs

[Steven Price <steven.price@arm.com>]

On 27/10/2025 16:13, Karunika Choo wrote:
> Add support for the GLB_REQ.STATE field introduced in CSF v4.1+, which
> replaces the HALT bit to provide finer control over the MCU state. This
> change implements basic handling for transitioning the MCU between
> ACTIVE and HALT states on Mali-G1 GPUs.
> 
> The update introduces new helpers to issue the state change requests,
> poll for MCU halt completion, and restore the MCU to an active state
> after halting.
> 
> Signed-off-by: Karunika Choo <karunika.choo@arm.com>

Reviewed-by: Steven Price <steven.price@arm.com>

> ---
> v3:
>  * Fixed missed CSF_IFACE_VERSION check with pathor_fw_has_glb_state().
> v2:
>  * Reduced MCU_HALT_TIMEOUT_US to 1 second.
>  * Wrap the CSG_IFACE_VERSION checks for v4.1.0 with
>    panthor_fw_has_glb_state().
>  * Removed use of undefined panthor_fw_csf_version() MACRO.
> ---
>  drivers/gpu/drm/panthor/panthor_fw.c | 89 +++++++++++++++++++++++-----
>  drivers/gpu/drm/panthor/panthor_fw.h |  7 +++
>  2 files changed, 80 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panthor/panthor_fw.c b/drivers/gpu/drm/panthor/panthor_fw.c
> index e6c39c70d348..fb1f69ef76fb 100644
> --- a/drivers/gpu/drm/panthor/panthor_fw.c
> +++ b/drivers/gpu/drm/panthor/panthor_fw.c
> @@ -33,6 +33,7 @@
>  #define PROGRESS_TIMEOUT_SCALE_SHIFT		10
>  #define IDLE_HYSTERESIS_US			800
>  #define PWROFF_HYSTERESIS_US			10000
> +#define MCU_HALT_TIMEOUT_US			(1ULL * USEC_PER_SEC)
> 
>  /**
>   * struct panthor_fw_binary_hdr - Firmware binary header.
> @@ -317,6 +318,13 @@ panthor_fw_get_cs_iface(struct panthor_device *ptdev, u32 csg_slot, u32 cs_slot)
>  	return &ptdev->fw->iface.streams[csg_slot][cs_slot];
>  }
> 
> +static bool panthor_fw_has_glb_state(struct panthor_device *ptdev)
> +{
> +	struct panthor_fw_global_iface *glb_iface = panthor_fw_get_glb_iface(ptdev);
> +
> +	return glb_iface->control->version >= CSF_IFACE_VERSION(4, 1, 0);
> +}
> +
>  /**
>   * panthor_fw_conv_timeout() - Convert a timeout into a cycle-count
>   * @ptdev: Device.
> @@ -996,6 +1004,9 @@ static void panthor_fw_init_global_iface(struct panthor_device *ptdev)
>  					 GLB_IDLE_EN |
>  					 GLB_IDLE;
> 
> +	if (panthor_fw_has_glb_state(ptdev))
> +		glb_iface->input->ack_irq_mask |= GLB_STATE_MASK;
> +
>  	panthor_fw_update_reqs(glb_iface, req, GLB_IDLE_EN, GLB_IDLE_EN);
>  	panthor_fw_toggle_reqs(glb_iface, req, ack,
>  			       GLB_CFG_ALLOC_EN |
> @@ -1069,6 +1080,54 @@ static void panthor_fw_stop(struct panthor_device *ptdev)
>  		drm_err(&ptdev->base, "Failed to stop MCU");
>  }
> 
> +static bool panthor_fw_mcu_halted(struct panthor_device *ptdev)
> +{
> +	struct panthor_fw_global_iface *glb_iface = panthor_fw_get_glb_iface(ptdev);
> +	bool halted;
> +
> +	halted = gpu_read(ptdev, MCU_STATUS) == MCU_STATUS_HALT;
> +
> +	if (panthor_fw_has_glb_state(ptdev))
> +		halted &= (GLB_STATE_GET(glb_iface->output->ack) == GLB_STATE_HALT);
> +
> +	return halted;
> +}
> +
> +static void panthor_fw_halt_mcu(struct panthor_device *ptdev)
> +{
> +	struct panthor_fw_global_iface *glb_iface = panthor_fw_get_glb_iface(ptdev);
> +
> +	if (panthor_fw_has_glb_state(ptdev))
> +		panthor_fw_update_reqs(glb_iface, req, GLB_STATE(GLB_STATE_HALT), GLB_STATE_MASK);
> +	else
> +		panthor_fw_update_reqs(glb_iface, req, GLB_HALT, GLB_HALT);
> +
> +	gpu_write(ptdev, CSF_DOORBELL(CSF_GLB_DOORBELL_ID), 1);
> +}
> +
> +static bool panthor_fw_wait_mcu_halted(struct panthor_device *ptdev)
> +{
> +	bool halted = false;
> +
> +	if (read_poll_timeout_atomic(panthor_fw_mcu_halted, halted, halted, 10,
> +				     MCU_HALT_TIMEOUT_US, 0, ptdev)) {
> +		drm_warn(&ptdev->base, "Timed out waiting for MCU to halt");
> +		return false;
> +	}
> +
> +	return true;
> +}
> +
> +static void panthor_fw_mcu_set_active(struct panthor_device *ptdev)
> +{
> +	struct panthor_fw_global_iface *glb_iface = panthor_fw_get_glb_iface(ptdev);
> +
> +	if (panthor_fw_has_glb_state(ptdev))
> +		panthor_fw_update_reqs(glb_iface, req, GLB_STATE(GLB_STATE_ACTIVE), GLB_STATE_MASK);
> +	else
> +		panthor_fw_update_reqs(glb_iface, req, 0, GLB_HALT);
> +}
> +
>  /**
>   * panthor_fw_pre_reset() - Call before a reset.
>   * @ptdev: Device.
> @@ -1085,19 +1144,13 @@ void panthor_fw_pre_reset(struct panthor_device *ptdev, bool on_hang)
>  	ptdev->reset.fast = false;
> 
>  	if (!on_hang) {
> -		struct panthor_fw_global_iface *glb_iface = panthor_fw_get_glb_iface(ptdev);
> -		u32 status;
> -
> -		panthor_fw_update_reqs(glb_iface, req, GLB_HALT, GLB_HALT);
> -		gpu_write(ptdev, CSF_DOORBELL(CSF_GLB_DOORBELL_ID), 1);
> -		if (!gpu_read_poll_timeout(ptdev, MCU_STATUS, status,
> -					   status == MCU_STATUS_HALT, 10,
> -					   100000)) {
> -			ptdev->reset.fast = true;
> -		} else {
> +		panthor_fw_halt_mcu(ptdev);
> +		if (!panthor_fw_wait_mcu_halted(ptdev))
>  			drm_warn(&ptdev->base, "Failed to cleanly suspend MCU");
> -		}
> +		else
> +			ptdev->reset.fast = true;
>  	}
> +	panthor_fw_stop(ptdev);
> 
>  	panthor_job_irq_suspend(&ptdev->fw->irq);
>  }
> @@ -1125,14 +1178,14 @@ int panthor_fw_post_reset(struct panthor_device *ptdev)
>  		 */
>  		panthor_reload_fw_sections(ptdev, true);
>  	} else {
> -		/* The FW detects 0 -> 1 transitions. Make sure we reset
> -		 * the HALT bit before the FW is rebooted.
> +		/*
> +		 * If the FW was previously successfully halted in the pre-reset
> +		 * operation, we need to transition it to active again before
> +		 * the FW is rebooted.
>  		 * This is not needed on a slow reset because FW sections are
>  		 * re-initialized.
>  		 */
> -		struct panthor_fw_global_iface *glb_iface = panthor_fw_get_glb_iface(ptdev);
> -
> -		panthor_fw_update_reqs(glb_iface, req, 0, GLB_HALT);
> +		panthor_fw_mcu_set_active(ptdev);
>  	}
> 
>  	ret = panthor_fw_start(ptdev);
> @@ -1170,6 +1223,10 @@ void panthor_fw_unplug(struct panthor_device *ptdev)
>  		if (ptdev->fw->irq.irq)
>  			panthor_job_irq_suspend(&ptdev->fw->irq);
> 
> +		panthor_fw_halt_mcu(ptdev);
> +		if (!panthor_fw_wait_mcu_halted(ptdev))
> +			drm_warn(&ptdev->base, "Failed to halt MCU on unplug");
> +
>  		panthor_fw_stop(ptdev);
>  	}
> 
> diff --git a/drivers/gpu/drm/panthor/panthor_fw.h b/drivers/gpu/drm/panthor/panthor_fw.h
> index 6598d96c6d2a..a19ed48b2d0b 100644
> --- a/drivers/gpu/drm/panthor/panthor_fw.h
> +++ b/drivers/gpu/drm/panthor/panthor_fw.h
> @@ -214,6 +214,13 @@ struct panthor_fw_global_input_iface {
>  #define GLB_FWCFG_UPDATE			BIT(9)
>  #define GLB_IDLE_EN				BIT(10)
>  #define GLB_SLEEP				BIT(12)
> +#define GLB_STATE_MASK				GENMASK(14, 12)
> +#define   GLB_STATE_ACTIVE			0
> +#define   GLB_STATE_HALT			1
> +#define   GLB_STATE_SLEEP			2
> +#define   GLB_STATE_SUSPEND			3
> +#define   GLB_STATE(x)				(((x) << 12) & GLB_STATE_MASK)
> +#define   GLB_STATE_GET(x)			(((x) & GLB_STATE_MASK) >> 12)
>  #define GLB_INACTIVE_COMPUTE			BIT(20)
>  #define GLB_INACTIVE_FRAGMENT			BIT(21)
>  #define GLB_INACTIVE_TILER			BIT(22)
> --
> 2.49.0
>