Re: [Freedreno] [PATCH 2/3] drm/msm: add DRM_MSM_GEM_SYNC_CACHE for non-coherent cache maintenance

From: Jordan Crouse <jcrouse@codeaurora.org>
To: Jonathan Marek <jonathan@marek.ca>
Cc: freedreno@lists.freedesktop.org, David Airlie <airlied@linux.ie>,
	"open list:DRM DRIVER FOR MSM ADRENO GPU" 
	<linux-arm-msm@vger.kernel.org>,
	open list <linux-kernel@vger.kernel.org>,
	"open list:DRM DRIVER FOR MSM ADRENO GPU" 
	<dri-devel@lists.freedesktop.org>,
	Rob Clark <robdclark@gmail.com>, Daniel Vetter <daniel@ffwll.ch>,
	Sean Paul <sean@poorly.run>
Subject: Re: [Freedreno] [PATCH 2/3] drm/msm: add DRM_MSM_GEM_SYNC_CACHE for non-coherent cache maintenance
Date: Thu, 1 Oct 2020 17:29:07 -0600	[thread overview]
Message-ID: <20201001232907.GG29832@jcrouse1-lnx.qualcomm.com> (raw)
In-Reply-To: <20201001002709.21361-3-jonathan@marek.ca>

On Wed, Sep 30, 2020 at 08:27:05PM -0400, 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@marek.ca>
> ---
>  drivers/gpu/drm/msm/msm_drv.c | 21 +++++++++++++++++++++
>  drivers/gpu/drm/msm/msm_drv.h |  2 ++
>  drivers/gpu/drm/msm/msm_gem.c | 15 +++++++++++++++
>  include/uapi/drm/msm_drm.h    | 20 ++++++++++++++++++++
>  4 files changed, 58 insertions(+)
> 
> diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
> index 9716210495fc..305db1db1064 100644
> --- a/drivers/gpu/drm/msm/msm_drv.c
> +++ b/drivers/gpu/drm/msm/msm_drv.c
> @@ -964,6 +964,26 @@ 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),
> @@ -976,6 +996,7 @@ 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 6384844b1696..5e932dae453f 100644
> --- a/drivers/gpu/drm/msm/msm_drv.h
> +++ b/drivers/gpu/drm/msm/msm_drv.h
> @@ -314,6 +314,8 @@ void msm_gem_move_to_active(struct drm_gem_object *obj,
>  void msm_gem_move_to_inactive(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 ad9a627493ae..93da88b3fc50 100644
> --- a/drivers/gpu/drm/msm/msm_gem.c
> +++ b/drivers/gpu/drm/msm/msm_gem.c
> @@ -8,6 +8,7 @@
>  #include <linux/shmem_fs.h>
>  #include <linux/dma-buf.h>
>  #include <linux/pfn_t.h>
> +#include <linux/dma-noncoherent.h>
>  
>  #include <drm/drm_prime.h>
>  
> @@ -808,6 +809,20 @@ 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);
> +
> +	/* TODO: sync only the required range, and don't invalidate on clean */
> +
> +	if (flags & MSM_GEM_SYNC_CACHE_CLEAN)

Curious why you would rename these - I feel like the to_device / to_cpu model is
pretty well baked into our thought process. I know from personal experience that
I have to stop and think to remember which direction is which.

Jordan

> +		sync_for_device(msm_obj);
> +
> +	if (flags & MSM_GEM_SYNC_CACHE_INVALIDATE)
> +		sync_for_cpu(msm_obj);
> +}
> +
>  #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..1dfafa71fc94 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_CACHE_CLEAN	0x1
> +#define MSM_GEM_SYNC_CACHE_INVALIDATE	0x2
> +
> +#define MSM_GEM_SYNC_CACHE_FLAGS	(MSM_GEM_SYNC_CACHE_CLEAN | \
> +					 MSM_GEM_SYNC_CACHE_INVALIDATE)
> +
> +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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> Freedreno@lists.freedesktop.org
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