Re: [PATCH 7/8] drm/panthor: Use a local iomem base for firmware control registers

[Boris Brezillon <boris.brezillon@collabora.com>]

On Fri, 10 Apr 2026 17:46:36 +0100
Karunika Choo <karunika.choo@arm.com> wrote:

> Add an MCU_CONTROL-local iomem pointer to struct panthor_fw and use it
> for firmware control and status register accesses.
> 
> Job interrupt accesses continue to go through the IRQ-local base, while
> doorbell writes stay on the device-wide mapping because they live
> outside the MCU control window. This keeps firmware register accesses
> scoped to the component that owns them.
> 
> No functional change intended.
> 
> Signed-off-by: Karunika Choo <karunika.choo@arm.com>

Acked-by: Boris Brezillon <boris.brezillon@collabora.com>

> ---
>  drivers/gpu/drm/panthor/panthor_fw.c      | 20 +++++++++++++-------
>  drivers/gpu/drm/panthor/panthor_fw_regs.h | 11 ++++-------
>  2 files changed, 17 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panthor/panthor_fw.c b/drivers/gpu/drm/panthor/panthor_fw.c
> index 20747f42759f..bf7c2baefb79 100644
> --- a/drivers/gpu/drm/panthor/panthor_fw.c
> +++ b/drivers/gpu/drm/panthor/panthor_fw.c
> @@ -234,6 +234,9 @@ struct panthor_fw_iface {
>   * struct panthor_fw - Firmware management
>   */
>  struct panthor_fw {
> +	/** @iomem: CPU mapping of MCU_CONTROL iomem region */
> +	void __iomem *iomem;
> +
>  	/** @vm: MCU VM. */
>  	struct panthor_vm *vm;
>  
> @@ -1069,7 +1072,7 @@ static void panthor_job_irq_handler(struct panthor_device *ptdev, u32 status)
>  	if (tracepoint_enabled(gpu_job_irq))
>  		start = ktime_get_ns();
>  
> -	gpu_write(ptdev->iomem, JOB_INT_CLEAR, status);
> +	gpu_write(ptdev->fw->irq.iomem, INT_CLEAR, status);
>  
>  	if (!ptdev->fw->booted && (status & JOB_INT_GLOBAL_IF))
>  		ptdev->fw->booted = true;
> @@ -1092,18 +1095,19 @@ PANTHOR_IRQ_HANDLER(job, panthor_job_irq_handler);
>  
>  static int panthor_fw_start(struct panthor_device *ptdev)
>  {
> +	struct panthor_fw *fw = ptdev->fw;
>  	bool timedout = false;
>  
>  	ptdev->fw->booted = false;
>  	panthor_job_irq_enable_events(&ptdev->fw->irq, ~0);
>  	panthor_job_irq_resume(&ptdev->fw->irq);
> -	gpu_write(ptdev->iomem, MCU_CONTROL, MCU_CONTROL_AUTO);
> +	gpu_write(fw->iomem, MCU_CONTROL, MCU_CONTROL_AUTO);
>  
>  	if (!wait_event_timeout(ptdev->fw->req_waitqueue,
>  				ptdev->fw->booted,
>  				msecs_to_jiffies(1000))) {
>  		if (!ptdev->fw->booted &&
> -		    !(gpu_read(ptdev->iomem, JOB_INT_STAT) & JOB_INT_GLOBAL_IF))
> +		    !(gpu_read(fw->irq.iomem, INT_STAT) & JOB_INT_GLOBAL_IF))
>  			timedout = true;
>  	}
>  
> @@ -1114,7 +1118,7 @@ static int panthor_fw_start(struct panthor_device *ptdev)
>  			[MCU_STATUS_HALT] = "halt",
>  			[MCU_STATUS_FATAL] = "fatal",
>  		};
> -		u32 status = gpu_read(ptdev->iomem, MCU_STATUS);
> +		u32 status = gpu_read(fw->iomem, MCU_STATUS);
>  
>  		drm_err(&ptdev->base, "Failed to boot MCU (status=%s)",
>  			status < ARRAY_SIZE(status_str) ? status_str[status] : "unknown");
> @@ -1126,10 +1130,11 @@ static int panthor_fw_start(struct panthor_device *ptdev)
>  
>  static void panthor_fw_stop(struct panthor_device *ptdev)
>  {
> +	struct panthor_fw *fw = ptdev->fw;
>  	u32 status;
>  
> -	gpu_write(ptdev->iomem, MCU_CONTROL, MCU_CONTROL_DISABLE);
> -	if (gpu_read_poll_timeout(ptdev->iomem, MCU_STATUS, status,
> +	gpu_write(fw->iomem, MCU_CONTROL, MCU_CONTROL_DISABLE);
> +	if (gpu_read_poll_timeout(fw->iomem, MCU_STATUS, status,
>  				  status == MCU_STATUS_DISABLED, 10, 100000))
>  		drm_err(&ptdev->base, "Failed to stop MCU");
>  }
> @@ -1139,7 +1144,7 @@ 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->iomem, MCU_STATUS) == MCU_STATUS_HALT;
> +	halted = gpu_read(ptdev->fw->iomem, MCU_STATUS) == MCU_STATUS_HALT;
>  
>  	if (panthor_fw_has_glb_state(ptdev))
>  		halted &= (GLB_STATE_GET(glb_iface->output->ack) == GLB_STATE_HALT);
> @@ -1461,6 +1466,7 @@ int panthor_fw_init(struct panthor_device *ptdev)
>  	if (!fw)
>  		return -ENOMEM;
>  
> +	fw->iomem = ptdev->iomem + MCU_CONTROL_BASE;
>  	ptdev->fw = fw;
>  	init_waitqueue_head(&fw->req_waitqueue);
>  	INIT_LIST_HEAD(&fw->sections);
> diff --git a/drivers/gpu/drm/panthor/panthor_fw_regs.h b/drivers/gpu/drm/panthor/panthor_fw_regs.h
> index eeb41aff249b..b2e59cfc22b0 100644
> --- a/drivers/gpu/drm/panthor/panthor_fw_regs.h
> +++ b/drivers/gpu/drm/panthor/panthor_fw_regs.h
> @@ -4,23 +4,20 @@
>  #ifndef __PANTHOR_FW_REGS_H__
>  #define __PANTHOR_FW_REGS_H__
>  
> -#define MCU_CONTROL					0x700
> +#define MCU_CONTROL_BASE				0x700
> +
> +#define MCU_CONTROL					0x0
>  #define   MCU_CONTROL_ENABLE				1
>  #define   MCU_CONTROL_AUTO				2
>  #define   MCU_CONTROL_DISABLE				0
>  
> -#define MCU_STATUS					0x704
> +#define MCU_STATUS					0x4
>  #define   MCU_STATUS_DISABLED				0
>  #define   MCU_STATUS_ENABLED				1
>  #define   MCU_STATUS_HALT				2
>  #define   MCU_STATUS_FATAL				3
>  
>  #define JOB_INT_BASE					0x1000
> -
> -#define JOB_INT_RAWSTAT					0x1000
> -#define JOB_INT_CLEAR					0x1004
> -#define JOB_INT_MASK					0x1008
> -#define JOB_INT_STAT					0x100c
>  #define   JOB_INT_GLOBAL_IF				BIT(31)
>  #define   JOB_INT_CSG_IF(x)				BIT(x)
>