Re: [PATCH v3 7/8] drm/panthor: Use a local iomem base for firmware control registers

Boris Brezillon
2026-04-30T10:44:28Z

On Mon, 27 Apr 2026 16:59:33 +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.
>
> v3:
> - Pick up R-bs from Liviu and Steve
> v2:
> - Pick up Ack from Boris.
>
> Reviewed-by: Steven Price <steven.price@arm.com>
> Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
> Acked-by: Boris Brezillon <boris.brezillon@collabora.com>
> Signed-off-by: Karunika Choo <karunika.choo@arm.com>

Tested-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 73ef07a37e22..986151681b24 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)
>