From: Chia-I Wu <olvaffe@gmail.com>
To: Boris Brezillon <boris.brezillon@collabora.com>
Cc: Steven Price <steven.price@arm.com>,
Liviu Dudau <liviu.dudau@arm.com>,
Sumit Semwal <sumit.semwal@linaro.org>,
Christian König <christian.koenig@amd.com>,
Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
Maxime Ripard <mripard@kernel.org>,
Thomas Zimmermann <tzimmermann@suse.de>,
David Airlie <airlied@gmail.com>, Simona Vetter <simona@ffwll.ch>,
linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org,
linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 5/6] drm/panthor: Use the drm_dev_access guard
Date: Thu, 14 May 2026 11:36:40 -0700 [thread overview]
Message-ID: <CAPaKu7TPe3ohss2=4S=jL=egsbNWxOvu7KW+6mN3arvVmo3r-w@mail.gmail.com> (raw)
In-Reply-To: <20260513-panthor-guard-refactor-v1-5-f2d8c15a97ce@collabora.com>
On Wed, May 13, 2026 at 10:09 AM Boris Brezillon
<boris.brezillon@collabora.com> wrote:
>
> It simplifies the code in a few places, allowing direct returns instead
> of gotos. It also helps identifying the sections under the dev_access
> guard when scoped_cond_guard() is used.
>
> Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Chia-I Wu <olvaffe@gmail.com>
> ---
> drivers/gpu/drm/panthor/panthor_device.c | 127 ++++++++++++++-----------------
> drivers/gpu/drm/panthor/panthor_drv.c | 58 ++++++--------
> drivers/gpu/drm/panthor/panthor_mmu.c | 29 +++----
> drivers/gpu/drm/panthor/panthor_sched.c | 10 +--
> 4 files changed, 95 insertions(+), 129 deletions(-)
>
> diff --git a/drivers/gpu/drm/panthor/panthor_device.c b/drivers/gpu/drm/panthor/panthor_device.c
> index cb9cd8d0448b..988a9a34f753 100644
> --- a/drivers/gpu/drm/panthor/panthor_device.c
> +++ b/drivers/gpu/drm/panthor/panthor_device.c
> @@ -123,7 +123,7 @@ static void panthor_device_reset_cleanup(struct drm_device *ddev, void *data)
> static void panthor_device_reset_work(struct work_struct *work)
> {
> struct panthor_device *ptdev = container_of(work, struct panthor_device, reset.work);
> - int ret = 0, cookie;
> + int ret = 0;
>
> /* If the device is entering suspend, we don't reset. A slow reset will
> * be forced at resume time instead.
> @@ -131,19 +131,17 @@ static void panthor_device_reset_work(struct work_struct *work)
> if (atomic_read(&ptdev->pm.state) != PANTHOR_DEVICE_PM_STATE_ACTIVE)
> return;
>
> - if (!drm_dev_enter(&ptdev->base, &cookie))
> - return;
> -
> - panthor_sched_pre_reset(ptdev);
> - panthor_fw_pre_reset(ptdev, true);
> - panthor_mmu_pre_reset(ptdev);
> - panthor_hw_soft_reset(ptdev);
> - panthor_hw_l2_power_on(ptdev);
> - panthor_mmu_post_reset(ptdev);
> - ret = panthor_fw_post_reset(ptdev);
> - atomic_set(&ptdev->reset.pending, 0);
> - panthor_sched_post_reset(ptdev, ret != 0);
> - drm_dev_exit(cookie);
> + scoped_cond_guard(drm_dev_access, return, &ptdev->base) {
> + panthor_sched_pre_reset(ptdev);
> + panthor_fw_pre_reset(ptdev, true);
> + panthor_mmu_pre_reset(ptdev);
> + panthor_hw_soft_reset(ptdev);
> + panthor_hw_l2_power_on(ptdev);
> + panthor_mmu_post_reset(ptdev);
> + ret = panthor_fw_post_reset(ptdev);
> + atomic_set(&ptdev->reset.pending, 0);
> + panthor_sched_post_reset(ptdev, ret != 0);
> + }
>
> if (ret) {
> panthor_device_unplug(ptdev);
> @@ -394,38 +392,31 @@ static vm_fault_t panthor_mmio_vm_fault(struct vm_fault *vmf)
> u64 offset = (u64)vma->vm_pgoff << PAGE_SHIFT;
> unsigned long pfn;
> pgprot_t pgprot;
> - vm_fault_t ret;
> bool active;
> - int cookie;
>
> - if (!drm_dev_enter(&ptdev->base, &cookie))
> + ACQUIRE(drm_dev_access, dev_guard)(&ptdev->base);
> + if (ACQUIRE_ERR(drm_dev_access, &dev_guard))
> return VM_FAULT_SIGBUS;
>
> - scoped_guard(mutex, &ptdev->pm.mmio_lock) {
> - active = atomic_read(&ptdev->pm.state) == PANTHOR_DEVICE_PM_STATE_ACTIVE;
> + guard(mutex)(&ptdev->pm.mmio_lock);
> + active = atomic_read(&ptdev->pm.state) == PANTHOR_DEVICE_PM_STATE_ACTIVE;
>
> - switch (offset) {
> - case DRM_PANTHOR_USER_FLUSH_ID_MMIO_OFFSET:
> - if (active)
> - pfn = __phys_to_pfn(ptdev->phys_addr + CSF_GPU_LATEST_FLUSH_ID);
> - else
> - pfn = page_to_pfn(ptdev->pm.dummy_latest_flush);
> + switch (offset) {
> + case DRM_PANTHOR_USER_FLUSH_ID_MMIO_OFFSET:
> + if (active)
> + pfn = __phys_to_pfn(ptdev->phys_addr + CSF_GPU_LATEST_FLUSH_ID);
> + else
> + pfn = page_to_pfn(ptdev->pm.dummy_latest_flush);
>
> - pgprot = vma->vm_page_prot;
> - if (active)
> - pgprot = pgprot_noncached(pgprot);
> + pgprot = vma->vm_page_prot;
> + if (active)
> + pgprot = pgprot_noncached(pgprot);
>
> - ret = vmf_insert_pfn_prot(vma, vmf->address, pfn, pgprot);
> - break;
> + return vmf_insert_pfn_prot(vma, vmf->address, pfn, pgprot);
>
> - default:
> - ret = VM_FAULT_SIGBUS;
> - break;
> - }
> + default:
> + return VM_FAULT_SIGBUS;
> }
> -
> - drm_dev_exit(cookie);
> - return ret;
> }
>
> static const struct vm_operations_struct panthor_mmio_vm_ops = {
> @@ -482,7 +473,7 @@ static int panthor_device_resume_hw_components(struct panthor_device *ptdev)
> int panthor_device_resume(struct device *dev)
> {
> struct panthor_device *ptdev = dev_get_drvdata(dev);
> - int ret, cookie;
> + int ret;
>
> if (atomic_read(&ptdev->pm.state) != PANTHOR_DEVICE_PM_STATE_SUSPENDED)
> return -EINVAL;
> @@ -503,28 +494,27 @@ int panthor_device_resume(struct device *dev)
>
> panthor_devfreq_resume(ptdev);
>
> - if (panthor_device_is_initialized(ptdev) &&
> - drm_dev_enter(&ptdev->base, &cookie)) {
> - /* If there was a reset pending at the time we suspended the
> - * device, we force a slow reset.
> - */
> - if (atomic_read(&ptdev->reset.pending)) {
> - ptdev->reset.fast = false;
> - atomic_set(&ptdev->reset.pending, 0);
> - }
> + if (panthor_device_is_initialized(ptdev)) {
> + scoped_cond_guard(drm_dev_access, ret = 0, &ptdev->base) {
> + /* If there was a reset pending at the time we suspended the
> + * device, we force a slow reset.
> + */
> + if (atomic_read(&ptdev->reset.pending)) {
> + ptdev->reset.fast = false;
> + atomic_set(&ptdev->reset.pending, 0);
> + }
>
> - ret = panthor_device_resume_hw_components(ptdev);
> - if (ret && ptdev->reset.fast) {
> - drm_err(&ptdev->base, "Fast reset failed, trying a slow reset");
> - ptdev->reset.fast = false;
> ret = panthor_device_resume_hw_components(ptdev);
> + if (ret && ptdev->reset.fast) {
> + drm_err(&ptdev->base, "Fast reset failed, trying a slow reset");
> + ptdev->reset.fast = false;
> + ret = panthor_device_resume_hw_components(ptdev);
> + }
> +
> + if (!ret)
> + panthor_sched_resume(ptdev);
> }
>
> - if (!ret)
> - panthor_sched_resume(ptdev);
> -
> - drm_dev_exit(cookie);
> -
> if (ret)
> goto err_suspend_devfreq;
> }
> @@ -559,7 +549,6 @@ int panthor_device_resume(struct device *dev)
> int panthor_device_suspend(struct device *dev)
> {
> struct panthor_device *ptdev = dev_get_drvdata(dev);
> - int cookie;
>
> if (atomic_read(&ptdev->pm.state) != PANTHOR_DEVICE_PM_STATE_ACTIVE)
> return -EINVAL;
> @@ -577,19 +566,19 @@ int panthor_device_suspend(struct device *dev)
> DRM_PANTHOR_USER_MMIO_OFFSET, 0, 1);
> }
>
> - if (panthor_device_is_initialized(ptdev) &&
> - drm_dev_enter(&ptdev->base, &cookie)) {
> - cancel_work_sync(&ptdev->reset.work);
> + if (panthor_device_is_initialized(ptdev)) {
> + scoped_guard(drm_dev_access, &ptdev->base) {
> + cancel_work_sync(&ptdev->reset.work);
>
> - /* We prepare everything as if we were resetting the GPU.
> - * The end of the reset will happen in the resume path though.
> - */
> - panthor_sched_suspend(ptdev);
> - panthor_fw_suspend(ptdev);
> - panthor_mmu_suspend(ptdev);
> - panthor_gpu_suspend(ptdev);
> - panthor_pwr_suspend(ptdev);
> - drm_dev_exit(cookie);
> + /* We prepare everything as if we were resetting the GPU.
> + * The end of the reset will happen in the resume path though.
> + */
> + panthor_sched_suspend(ptdev);
> + panthor_fw_suspend(ptdev);
> + panthor_mmu_suspend(ptdev);
> + panthor_gpu_suspend(ptdev);
> + panthor_pwr_suspend(ptdev);
> + }
> }
>
> panthor_devfreq_suspend(ptdev);
> diff --git a/drivers/gpu/drm/panthor/panthor_drv.c b/drivers/gpu/drm/panthor/panthor_drv.c
> index e8dc4096c1d2..789ddc0ff7ef 100644
> --- a/drivers/gpu/drm/panthor/panthor_drv.c
> +++ b/drivers/gpu/drm/panthor/panthor_drv.c
> @@ -997,9 +997,10 @@ static int panthor_ioctl_vm_create(struct drm_device *ddev, void *data,
> struct panthor_device *ptdev = container_of(ddev, struct panthor_device, base);
> struct panthor_file *pfile = file->driver_priv;
> struct drm_panthor_vm_create *args = data;
> - int cookie, ret;
> + int ret;
>
> - if (!drm_dev_enter(ddev, &cookie))
> + ACQUIRE(drm_dev_access, dev_guard)(ddev);
> + if (ACQUIRE_ERR(drm_dev_access, &dev_guard))
> return -ENODEV;
>
> ret = panthor_vm_pool_create_vm(ptdev, pfile->vms, args);
> @@ -1008,7 +1009,6 @@ static int panthor_ioctl_vm_create(struct drm_device *ddev, void *data,
> ret = 0;
> }
>
> - drm_dev_exit(cookie);
> return ret;
> }
>
> @@ -1033,38 +1033,30 @@ static int panthor_ioctl_bo_create(struct drm_device *ddev, void *data,
> struct panthor_file *pfile = file->driver_priv;
> struct drm_panthor_bo_create *args = data;
> struct panthor_vm *vm = NULL;
> - int cookie, ret;
> + int ret;
>
> - if (!drm_dev_enter(ddev, &cookie))
> + ACQUIRE(drm_dev_access, dev_guard)(ddev);
> + if (ACQUIRE_ERR(drm_dev_access, &dev_guard))
> return -ENODEV;
>
> if (!args->size || args->pad ||
> - (args->flags & ~PANTHOR_BO_FLAGS)) {
> - ret = -EINVAL;
> - goto out_dev_exit;
> - }
> + (args->flags & ~PANTHOR_BO_FLAGS))
> + return -EINVAL;
>
> if ((args->flags & DRM_PANTHOR_BO_NO_MMAP) &&
> - (args->flags & DRM_PANTHOR_BO_WB_MMAP)) {
> - ret = -EINVAL;
> - goto out_dev_exit;
> - }
> + (args->flags & DRM_PANTHOR_BO_WB_MMAP))
> + return -EINVAL;
>
> if (args->exclusive_vm_id) {
> vm = panthor_vm_pool_get_vm(pfile->vms, args->exclusive_vm_id);
> - if (!vm) {
> - ret = -EINVAL;
> - goto out_dev_exit;
> - }
> + if (!vm)
> + return -EINVAL;
> }
>
> ret = panthor_gem_create_with_handle(file, ddev, vm, &args->size,
> args->flags, &args->handle);
>
> panthor_vm_put(vm);
> -
> -out_dev_exit:
> - drm_dev_exit(cookie);
> return ret;
> }
>
> @@ -1107,17 +1099,18 @@ static int panthor_ioctl_group_submit(struct drm_device *ddev, void *data,
> struct drm_panthor_group_submit *args = data;
> struct drm_panthor_queue_submit *jobs_args;
> struct panthor_submit_ctx ctx;
> - int ret = 0, cookie;
> + int ret = 0;
>
> if (args->pad)
> return -EINVAL;
>
> - if (!drm_dev_enter(ddev, &cookie))
> + ACQUIRE(drm_dev_access, dev_guard)(ddev);
> + if (ACQUIRE_ERR(drm_dev_access, &dev_guard))
> return -ENODEV;
>
> ret = PANTHOR_UOBJ_GET_ARRAY(jobs_args, &args->queue_submits);
> if (ret)
> - goto out_dev_exit;
> + return ret;
>
> ret = panthor_submit_ctx_init(&ctx, file, args->queue_submits.count);
> if (ret)
> @@ -1201,8 +1194,6 @@ static int panthor_ioctl_group_submit(struct drm_device *ddev, void *data,
> out_free_jobs_args:
> kvfree(jobs_args);
>
> -out_dev_exit:
> - drm_dev_exit(cookie);
> return ret;
> }
>
> @@ -1438,18 +1429,15 @@ static int panthor_ioctl_vm_bind(struct drm_device *ddev, void *data,
> struct drm_file *file)
> {
> struct drm_panthor_vm_bind *args = data;
> - int cookie, ret;
>
> - if (!drm_dev_enter(ddev, &cookie))
> + ACQUIRE(drm_dev_access, dev_guard)(ddev);
> + if (ACQUIRE_ERR(drm_dev_access, &dev_guard))
> return -ENODEV;
>
> if (args->flags & DRM_PANTHOR_VM_BIND_ASYNC)
> - ret = panthor_ioctl_vm_bind_async(ddev, args, file);
> - else
> - ret = panthor_ioctl_vm_bind_sync(ddev, args, file);
> + return panthor_ioctl_vm_bind_async(ddev, args, file);
>
> - drm_dev_exit(cookie);
> - return ret;
> + return panthor_ioctl_vm_bind_sync(ddev, args, file);
> }
>
> static int panthor_ioctl_vm_get_state(struct drm_device *ddev, void *data,
> @@ -1671,9 +1659,10 @@ static int panthor_mmap(struct file *filp, struct vm_area_struct *vma)
> struct panthor_device *ptdev = pfile->ptdev;
> u64 offset = (u64)vma->vm_pgoff << PAGE_SHIFT;
> u64 user_mmio_offset;
> - int ret, cookie;
> + int ret;
>
> - if (!drm_dev_enter(file->minor->dev, &cookie))
> + ACQUIRE(drm_dev_access, dev_guard)(file->minor->dev);
> + if (ACQUIRE_ERR(drm_dev_access, &dev_guard))
> return -ENODEV;
>
> /* Adjust the user MMIO offset to match the offset used kernel side.
> @@ -1691,7 +1680,6 @@ static int panthor_mmap(struct file *filp, struct vm_area_struct *vma)
> ret = drm_gem_mmap(filp, vma);
> }
>
> - drm_dev_exit(cookie);
> return ret;
> }
>
> diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
> index ab9a77e6a145..ff3beb9147e8 100644
> --- a/drivers/gpu/drm/panthor/panthor_mmu.c
> +++ b/drivers/gpu/drm/panthor/panthor_mmu.c
> @@ -788,13 +788,13 @@ static int panthor_vm_active_locked(struct panthor_vm *vm)
> int panthor_vm_active(struct panthor_vm *vm)
> {
> struct panthor_device *ptdev = vm->ptdev;
> - int ret = 0, cookie;
>
> - if (!drm_dev_enter(&ptdev->base, &cookie))
> + ACQUIRE(drm_dev_access, dev_guard)(&ptdev->base);
> + if (ACQUIRE_ERR(drm_dev_access, &dev_guard))
> return -ENODEV;
>
> if (refcount_inc_not_zero(&vm->as.active_cnt))
> - goto out_dev_exit;
> + return 0;
>
> /* As soon as active is called, we place the VM at the end of the VM LRU.
> * If something fails after that, the only downside is that this VM that
> @@ -809,14 +809,10 @@ int panthor_vm_active(struct panthor_vm *vm)
> /* Make sure we don't race with lock/unlock_region() calls
> * happening around VM bind operations.
> */
> - scoped_guard(mutex, &vm->op_lock) {
> - guard(mutex)(&ptdev->mmu->as.slots_lock);
> - ret = panthor_vm_active_locked(vm);
> - }
> + guard(mutex)(&vm->op_lock);
> + guard(mutex)(&ptdev->mmu->as.slots_lock);
>
> -out_dev_exit:
> - drm_dev_exit(cookie);
> - return ret;
> + return panthor_vm_active_locked(vm);
> }
>
> /**
> @@ -902,16 +898,15 @@ static size_t get_pgsize(u64 addr, size_t size, size_t *count)
> static void panthor_vm_declare_unusable(struct panthor_vm *vm)
> {
> struct panthor_device *ptdev = vm->ptdev;
> - int cookie;
>
> if (vm->unusable)
> return;
>
> vm->unusable = true;
> guard(mutex)(&ptdev->mmu->as.slots_lock);
> - if (vm->as.id >= 0 && drm_dev_enter(&ptdev->base, &cookie)) {
> - panthor_mmu_as_disable(ptdev, vm->as.id, false);
> - drm_dev_exit(cookie);
> + if (vm->as.id >= 0) {
> + scoped_guard(drm_dev_access, &ptdev->base)
> + panthor_mmu_as_disable(ptdev, vm->as.id, false);
> }
> }
>
> @@ -1983,12 +1978,8 @@ static void panthor_vm_free(struct drm_gpuvm *gpuvm)
> scoped_guard(mutex, &vm->op_lock) {
> guard(mutex)(&ptdev->mmu->as.slots_lock);
> if (vm->as.id >= 0) {
> - int cookie;
> -
> - if (drm_dev_enter(&ptdev->base, &cookie)) {
> + scoped_guard(drm_dev_access, &ptdev->base)
> panthor_mmu_as_disable(ptdev, vm->as.id, false);
> - drm_dev_exit(cookie);
> - }
>
> ptdev->mmu->as.slots[vm->as.id].vm = NULL;
> clear_bit(vm->as.id, &ptdev->mmu->as.alloc_mask);
> diff --git a/drivers/gpu/drm/panthor/panthor_sched.c b/drivers/gpu/drm/panthor/panthor_sched.c
> index d8cadd393fbe..9aa9941d2309 100644
> --- a/drivers/gpu/drm/panthor/panthor_sched.c
> +++ b/drivers/gpu/drm/panthor/panthor_sched.c
> @@ -2624,21 +2624,19 @@ static void tick_work(struct work_struct *work)
> struct panthor_scheduler *sched = container_of(work, struct panthor_scheduler,
> tick_work.work);
> struct panthor_device *ptdev = sched->ptdev;
> - int ret, cookie;
> + int ret;
>
> - if (!drm_dev_enter(&ptdev->base, &cookie))
> + ACQUIRE(drm_dev_access, dev_guard)(&ptdev->base);
> + if (ACQUIRE_ERR(drm_dev_access, &dev_guard))
> return;
>
> ret = panthor_device_resume_and_get(ptdev);
> if (drm_WARN_ON(&ptdev->base, ret))
> - goto out_dev_exit;
> + return;
>
> tick(sched);
> pm_runtime_mark_last_busy(ptdev->base.dev);
> pm_runtime_put_autosuspend(ptdev->base.dev);
> -
> -out_dev_exit:
> - drm_dev_exit(cookie);
> }
>
> static int panthor_queue_eval_syncwait(struct panthor_group *group, u8 queue_idx)
>
> --
> 2.54.0
>
next prev parent reply other threads:[~2026-05-14 18:36 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-13 16:58 [PATCH 0/6] drm/panthor: Use guards Boris Brezillon
2026-05-13 16:58 ` [PATCH 1/6] drm/panthor: Driver-wide xxx_[un]lock -> [scoped_]guard replacement Boris Brezillon
2026-05-14 13:16 ` Steven Price
2026-05-14 17:09 ` Chia-I Wu
2026-05-16 1:40 ` Claude review: " Claude Code Review Bot
2026-05-13 16:58 ` [PATCH 2/6] dma-resv: Define guards for context-less dma_resv locks Boris Brezillon
2026-05-14 18:23 ` Chia-I Wu
2026-05-16 1:40 ` Claude review: " Claude Code Review Bot
2026-05-13 16:58 ` [PATCH 3/6] drm: Define a conditional guard for drm_dev_{enter,exit}() Boris Brezillon
2026-05-14 18:34 ` [PATCH 3/6] drm: Define a conditional guard for drm_dev_{enter, exit}() Chia-I Wu
2026-05-16 1:40 ` Claude review: drm: Define a conditional guard for drm_dev_{enter,exit}() Claude Code Review Bot
2026-05-13 16:58 ` [PATCH 4/6] drm/panthor: Use guards for resv locking Boris Brezillon
2026-05-14 18:35 ` Chia-I Wu
2026-05-16 1:40 ` Claude review: " Claude Code Review Bot
2026-05-13 16:58 ` [PATCH 5/6] drm/panthor: Use the drm_dev_access guard Boris Brezillon
2026-05-14 18:36 ` Chia-I Wu [this message]
2026-05-16 1:40 ` Claude review: " Claude Code Review Bot
2026-05-13 16:58 ` [PATCH 6/6] drm/panthor: Add a new guard for our custom resume_and_get() PM helper Boris Brezillon
2026-05-14 18:39 ` Chia-I Wu
2026-05-16 1:40 ` Claude review: " Claude Code Review Bot
2026-05-16 1:40 ` Claude review: drm/panthor: Use guards Claude Code Review Bot
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