Re: [Freedreno] [RESEND PATCH v2 4/5] drm/msm: add DRM_MSM_GEM_SYNC_CACHE for non-coherent cache maintenance

From: Jordan Crouse
Date: Mon Nov 16 2020 - 12:26:03 EST

On Sat, Nov 14, 2020 at 10:17:12AM -0500, Jonathan Marek wrote:
> This makes it possible to use the non-coherent cached MSM_BO_CACHED mode,
> which otherwise doesn't provide any method for cleaning/invalidating the
> cache to sync with the device.
>
> Signed-off-by: Jonathan Marek <jonathan@xxxxxxxx>
> ---
> drivers/gpu/drm/msm/msm_drv.c | 21 +++++++++++++++++++++
> drivers/gpu/drm/msm/msm_drv.h | 2 ++
> drivers/gpu/drm/msm/msm_gem.c | 23 +++++++++++++++++++++++
> include/uapi/drm/msm_drm.h | 20 ++++++++++++++++++++
> 4 files changed, 66 insertions(+)
>
> diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
> index bae48afca82e..3f17acdf6594 100644
> --- a/drivers/gpu/drm/msm/msm_drv.c
> +++ b/drivers/gpu/drm/msm/msm_drv.c
> @@ -959,6 +959,26 @@ static int msm_ioctl_submitqueue_close(struct drm_device *dev, void *data,
> return msm_submitqueue_remove(file->driver_priv, id);
> }
>
> +static int msm_ioctl_gem_sync_cache(struct drm_device *dev, void *data,
> + struct drm_file *file)
> +{
> + struct drm_msm_gem_sync_cache *args = data;
> + struct drm_gem_object *obj;
> +
> + if (args->flags & ~MSM_GEM_SYNC_CACHE_FLAGS)
> + return -EINVAL;
> +
> + obj = drm_gem_object_lookup(file, args->handle);
> + if (!obj)
> + return -ENOENT;
> +
> + msm_gem_sync_cache(obj, args->flags, args->offset, args->end);
> +
> + drm_gem_object_put(obj);
> +
> + return 0;
> +}
> +
> static const struct drm_ioctl_desc msm_ioctls[] = {
> DRM_IOCTL_DEF_DRV(MSM_GET_PARAM, msm_ioctl_get_param, DRM_RENDER_ALLOW),
> DRM_IOCTL_DEF_DRV(MSM_GEM_NEW, msm_ioctl_gem_new, DRM_RENDER_ALLOW),
> @@ -971,6 +991,7 @@ static const struct drm_ioctl_desc msm_ioctls[] = {
> DRM_IOCTL_DEF_DRV(MSM_SUBMITQUEUE_NEW, msm_ioctl_submitqueue_new, DRM_RENDER_ALLOW),
> DRM_IOCTL_DEF_DRV(MSM_SUBMITQUEUE_CLOSE, msm_ioctl_submitqueue_close, DRM_RENDER_ALLOW),
> DRM_IOCTL_DEF_DRV(MSM_SUBMITQUEUE_QUERY, msm_ioctl_submitqueue_query, DRM_RENDER_ALLOW),
> + DRM_IOCTL_DEF_DRV(MSM_GEM_SYNC_CACHE, msm_ioctl_gem_sync_cache, DRM_RENDER_ALLOW),
> };
>
> static const struct vm_operations_struct vm_ops = {
> diff --git a/drivers/gpu/drm/msm/msm_drv.h b/drivers/gpu/drm/msm/msm_drv.h
> index 22ebecb28349..f170f843010e 100644
> --- a/drivers/gpu/drm/msm/msm_drv.h
> +++ b/drivers/gpu/drm/msm/msm_drv.h
> @@ -318,6 +318,8 @@ void msm_gem_active_get(struct drm_gem_object *obj, struct msm_gpu *gpu);
> void msm_gem_active_put(struct drm_gem_object *obj);
> int msm_gem_cpu_prep(struct drm_gem_object *obj, uint32_t op, ktime_t *timeout);
> int msm_gem_cpu_fini(struct drm_gem_object *obj);
> +void msm_gem_sync_cache(struct drm_gem_object *obj, uint32_t flags,
> + size_t range_start, size_t range_end);
> void msm_gem_free_object(struct drm_gem_object *obj);
> int msm_gem_new_handle(struct drm_device *dev, struct drm_file *file,
> uint32_t size, uint32_t flags, uint32_t *handle, char *name);
> diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
> index 3d8254b5de16..039738696f9a 100644
> --- a/drivers/gpu/drm/msm/msm_gem.c
> +++ b/drivers/gpu/drm/msm/msm_gem.c
> @@ -797,6 +797,29 @@ int msm_gem_cpu_fini(struct drm_gem_object *obj)
> return 0;
> }
>
> +void msm_gem_sync_cache(struct drm_gem_object *obj, uint32_t flags,
> + size_t range_start, size_t range_end)
> +{
> + struct msm_gem_object *msm_obj = to_msm_bo(obj);
> + struct device *dev = msm_obj->base.dev->dev;
> +

On a6xx targets with I/O coherency you can skip this (assuming that the IOMMU
flag has been set for this buffer). I'm not sure if one of the other patches
already does the bypass but I mention it here since this is the point of
no-return.

Jordan

> + /* exit early if get_pages() hasn't been called yet */
> + if (!msm_obj->pages)
> + return;
> +
> + /* TODO: sync only the specified range */
> +
> + if (flags & MSM_GEM_SYNC_FOR_DEVICE) {
> + dma_sync_sg_for_device(dev, msm_obj->sgt->sgl,
> + msm_obj->sgt->nents, DMA_TO_DEVICE);
> + }
> +
> + if (flags & MSM_GEM_SYNC_FOR_CPU) {
> + dma_sync_sg_for_cpu(dev, msm_obj->sgt->sgl,
> + msm_obj->sgt->nents, DMA_FROM_DEVICE);
> + }
> +}
> +
> #ifdef CONFIG_DEBUG_FS
> static void describe_fence(struct dma_fence *fence, const char *type,
> struct seq_file *m)
> diff --git a/include/uapi/drm/msm_drm.h b/include/uapi/drm/msm_drm.h
> index 474497e8743a..c8288f328528 100644
> --- a/include/uapi/drm/msm_drm.h
> +++ b/include/uapi/drm/msm_drm.h
> @@ -319,6 +319,24 @@ struct drm_msm_submitqueue_query {
> __u32 pad;
> };
>
> +/*
> + * Host cache maintenance (relevant for MSM_BO_CACHED)
> + * driver may both clean/invalidate (flush) for clean
> + */
> +
> +#define MSM_GEM_SYNC_FOR_DEVICE 0x1
> +#define MSM_GEM_SYNC_FOR_CPU 0x2
> +
> +#define MSM_GEM_SYNC_CACHE_FLAGS (MSM_GEM_SYNC_FOR_DEVICE | \
> + MSM_GEM_SYNC_FOR_CPU)
> +
> +struct drm_msm_gem_sync_cache {
> + __u32 handle;
> + __u32 flags;
> + __u64 offset;
> + __u64 end; /* offset + size */
> +};
> +
> #define DRM_MSM_GET_PARAM 0x00
> /* placeholder:
> #define DRM_MSM_SET_PARAM 0x01
> @@ -336,6 +354,7 @@ struct drm_msm_submitqueue_query {
> #define DRM_MSM_SUBMITQUEUE_NEW 0x0A
> #define DRM_MSM_SUBMITQUEUE_CLOSE 0x0B
> #define DRM_MSM_SUBMITQUEUE_QUERY 0x0C
> +#define DRM_MSM_GEM_SYNC_CACHE 0x0D
>
> #define DRM_IOCTL_MSM_GET_PARAM DRM_IOWR(DRM_COMMAND_BASE + DRM_MSM_GET_PARAM, struct drm_msm_param)
> #define DRM_IOCTL_MSM_GEM_NEW DRM_IOWR(DRM_COMMAND_BASE + DRM_MSM_GEM_NEW, struct drm_msm_gem_new)
> @@ -348,6 +367,7 @@ struct drm_msm_submitqueue_query {
> #define DRM_IOCTL_MSM_SUBMITQUEUE_NEW DRM_IOWR(DRM_COMMAND_BASE + DRM_MSM_SUBMITQUEUE_NEW, struct drm_msm_submitqueue)
> #define DRM_IOCTL_MSM_SUBMITQUEUE_CLOSE DRM_IOW (DRM_COMMAND_BASE + DRM_MSM_SUBMITQUEUE_CLOSE, __u32)
> #define DRM_IOCTL_MSM_SUBMITQUEUE_QUERY DRM_IOW (DRM_COMMAND_BASE + DRM_MSM_SUBMITQUEUE_QUERY, struct drm_msm_submitqueue_query)
> +#define DRM_IOCTL_MSM_GEM_SYNC_CACHE DRM_IOW (DRM_COMMAND_BASE + DRM_MSM_GEM_SYNC_CACHE, struct drm_msm_gem_sync_cache)
>
> #if defined(__cplusplus)
> }
> --
> 2.26.1
>
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