diff mbox series

[v14,02/56] media: videobuf2: Rework offset 'cookie' encoding pattern

Message ID 20231031163104.112469-3-benjamin.gaignard@collabora.com
State New
Headers
Series Add DELETE_BUF ioctl |

Commit Message

Benjamin Gaignard Oct. 31, 2023, 4:30 p.m. UTC 
  Change how offset 'cookie' field value is computed to make possible
to use more buffers.
The maximum number of buffers depends of PAGE_SHIFT value and can
go up to 0x7fff when PAGE_SHIFT = 12.
With this encoding pattern we know the maximum number that a queue
could store so we can check it at  queue init time.
It also make easier and faster to find buffer and plane from using
the offset field.
Change __find_plane_by_offset() prototype to return the video buffer
itself rather than it index.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
---
 .../media/common/videobuf2/videobuf2-core.c   | 73 +++++++++----------
 1 file changed, 35 insertions(+), 38 deletions(-)

Comments

Tomasz Figa Nov. 8, 2023, 6:23 a.m. UTC | #1 
Hi Benjamin,

On Tue, Oct 31, 2023 at 05:30:10PM +0100, Benjamin Gaignard wrote:
> Change how offset 'cookie' field value is computed to make possible
> to use more buffers.
> The maximum number of buffers depends of PAGE_SHIFT value and can
> go up to 0x7fff when PAGE_SHIFT = 12.
> With this encoding pattern we know the maximum number that a queue
> could store so we can check it at  queue init time.
> It also make easier and faster to find buffer and plane from using
> the offset field.
> Change __find_plane_by_offset() prototype to return the video buffer
> itself rather than it index.
> 
> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
> ---
>  .../media/common/videobuf2/videobuf2-core.c   | 73 +++++++++----------
>  1 file changed, 35 insertions(+), 38 deletions(-)
> 

Thanks a lot for working on this series. Just one comment inline.

> diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
> index a5e57affeb30..09be8e026044 100644
> --- a/drivers/media/common/videobuf2/videobuf2-core.c
> +++ b/drivers/media/common/videobuf2/videobuf2-core.c
> @@ -31,6 +31,11 @@
>  
>  #include <trace/events/vb2.h>
>  
> +#define PLANE_INDEX_SHIFT	(PAGE_SHIFT + 3)
> +#define PLANE_INDEX_MASK	0x7

Could we somehow ensure that it indeed matches VIDEO_MAX_PLANES?

One thing that comes to my mind would be

#define PLANE_INDEX_BITS	3
#define PLANE_INDEX_SHIFT	(PAGE_SHIFT + PLANE_INDEX_BITS)
#define PLANE_INDEX_MASK	BIT_MASK(PLANE_INDEX_BITS)

BUILD_BUG_ON(BIT(PLANE_INDEX_BITS) != VIDEO_MAX_PLANES);

Alternatively we could change the videodev2.h, so that we have

#define VIDEO_MAX_PLANES_BITS	3
#define VIDEO_MAX_PLANES	(1U < VIDEO_MAX_PLANES_BITS)

and then we can just VIDEO_MAX_PLANES_BITS in our definitions in this file
and no checks would be necessary.

Best regards,
Tomasz

> +#define MAX_BUFFER_INDEX	BIT_MASK(30 - PLANE_INDEX_SHIFT)
> +#define BUFFER_INDEX_MASK	(MAX_BUFFER_INDEX - 1)
> +
>  static int debug;
>  module_param(debug, int, 0644);
>  
> @@ -358,21 +363,27 @@ static void __setup_offsets(struct vb2_buffer *vb)
>  	unsigned int plane;
>  	unsigned long offset = 0;
>  
> -	if (vb->index) {
> -		struct vb2_buffer *prev = q->bufs[vb->index - 1];
> -		struct vb2_plane *p = &prev->planes[prev->num_planes - 1];
> -
> -		offset = PAGE_ALIGN(p->m.offset + p->length);
> -	}
> +	/*
> +	 * The offset "cookie" value has the following constraints:
> +	 * - a buffer can have up to 8 planes.
> +	 * - v4l2 mem2mem uses bit 30 to distinguish between
> +	 *   OUTPUT (aka "source", bit 30 is 0) and
> +	 *   CAPTURE (aka "destination", bit 30 is 1) buffers.
> +	 * - must be page aligned
> +	 * That led to this bit mapping when PAGE_SHIFT = 12:
> +	 * |30                |29        15|14       12|11 0|
> +	 * |DST_QUEUE_OFF_BASE|buffer index|plane index| 0  |
> +	 * where there are 15 bits to store the buffer index.
> +	 * Depending on PAGE_SHIFT value we can have fewer bits
> +	 * to store the buffer index.
> +	 */
> +	offset = vb->index << PLANE_INDEX_SHIFT;
>  
>  	for (plane = 0; plane < vb->num_planes; ++plane) {
> -		vb->planes[plane].m.offset = offset;
> +		vb->planes[plane].m.offset = offset + (plane << PAGE_SHIFT);
>  
>  		dprintk(q, 3, "buffer %d, plane %d offset 0x%08lx\n",
>  				vb->index, plane, offset);
> -
> -		offset += vb->planes[plane].length;
> -		offset = PAGE_ALIGN(offset);
>  	}
>  }
>  
> @@ -2188,10 +2199,9 @@ EXPORT_SYMBOL_GPL(vb2_core_streamoff);
>   * __find_plane_by_offset() - find plane associated with the given offset
>   */
>  static int __find_plane_by_offset(struct vb2_queue *q, unsigned long offset,
> -			unsigned int *_buffer, unsigned int *_plane)
> +			struct vb2_buffer **vb, unsigned int *plane)
>  {
> -	struct vb2_buffer *vb;
> -	unsigned int buffer, plane;
> +	unsigned int buffer;
>  
>  	/*
>  	 * Sanity checks to ensure the lock is held, MEMORY_MMAP is
> @@ -2209,24 +2219,15 @@ static int __find_plane_by_offset(struct vb2_queue *q, unsigned long offset,
>  		return -EBUSY;
>  	}
>  
> -	/*
> -	 * Go over all buffers and their planes, comparing the given offset
> -	 * with an offset assigned to each plane. If a match is found,
> -	 * return its buffer and plane numbers.
> -	 */
> -	for (buffer = 0; buffer < q->num_buffers; ++buffer) {
> -		vb = q->bufs[buffer];
> +	/* Get buffer and plane from the offset */
> +	buffer = (offset >> PLANE_INDEX_SHIFT) & BUFFER_INDEX_MASK;
> +	*plane = (offset >> PAGE_SHIFT) & PLANE_INDEX_MASK;
>  
> -		for (plane = 0; plane < vb->num_planes; ++plane) {
> -			if (vb->planes[plane].m.offset == offset) {
> -				*_buffer = buffer;
> -				*_plane = plane;
> -				return 0;
> -			}
> -		}
> -	}
> +	if (buffer >= q->num_buffers || *plane >= q->bufs[buffer]->num_planes)
> +		return -EINVAL;
>  
> -	return -EINVAL;
> +	*vb = q->bufs[buffer];
> +	return 0;
>  }
>  
>  int vb2_core_expbuf(struct vb2_queue *q, int *fd, unsigned int type,
> @@ -2306,7 +2307,7 @@ int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma)
>  {
>  	unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
>  	struct vb2_buffer *vb;
> -	unsigned int buffer = 0, plane = 0;
> +	unsigned int plane = 0;
>  	int ret;
>  	unsigned long length;
>  
> @@ -2335,12 +2336,10 @@ int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma)
>  	 * Find the plane corresponding to the offset passed by userspace. This
>  	 * will return an error if not MEMORY_MMAP or file I/O is in progress.
>  	 */
> -	ret = __find_plane_by_offset(q, offset, &buffer, &plane);
> +	ret = __find_plane_by_offset(q, offset, &vb, &plane);
>  	if (ret)
>  		goto unlock;
>  
> -	vb = q->bufs[buffer];
> -
>  	/*
>  	 * MMAP requires page_aligned buffers.
>  	 * The buffer length was page_aligned at __vb2_buf_mem_alloc(),
> @@ -2368,7 +2367,7 @@ int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma)
>  	if (ret)
>  		return ret;
>  
> -	dprintk(q, 3, "buffer %d, plane %d successfully mapped\n", buffer, plane);
> +	dprintk(q, 3, "buffer %u, plane %d successfully mapped\n", vb->index, plane);
>  	return 0;
>  }
>  EXPORT_SYMBOL_GPL(vb2_mmap);
> @@ -2382,7 +2381,7 @@ unsigned long vb2_get_unmapped_area(struct vb2_queue *q,
>  {
>  	unsigned long offset = pgoff << PAGE_SHIFT;
>  	struct vb2_buffer *vb;
> -	unsigned int buffer, plane;
> +	unsigned int plane;
>  	void *vaddr;
>  	int ret;
>  
> @@ -2392,12 +2391,10 @@ unsigned long vb2_get_unmapped_area(struct vb2_queue *q,
>  	 * Find the plane corresponding to the offset passed by userspace. This
>  	 * will return an error if not MEMORY_MMAP or file I/O is in progress.
>  	 */
> -	ret = __find_plane_by_offset(q, offset, &buffer, &plane);
> +	ret = __find_plane_by_offset(q, offset, &vb, &plane);
>  	if (ret)
>  		goto unlock;
>  
> -	vb = q->bufs[buffer];
> -
>  	vaddr = vb2_plane_vaddr(vb, plane);
>  	mutex_unlock(&q->mmap_lock);
>  	return vaddr ? (unsigned long)vaddr : -EINVAL;
> -- 
> 2.39.2
>
Benjamin Gaignard Nov. 8, 2023, 10:14 a.m. UTC | #2 
Le 08/11/2023 à 07:23, Tomasz Figa a écrit :
> Hi Benjamin,
>
> On Tue, Oct 31, 2023 at 05:30:10PM +0100, Benjamin Gaignard wrote:
>> Change how offset 'cookie' field value is computed to make possible
>> to use more buffers.
>> The maximum number of buffers depends of PAGE_SHIFT value and can
>> go up to 0x7fff when PAGE_SHIFT = 12.
>> With this encoding pattern we know the maximum number that a queue
>> could store so we can check it at  queue init time.
>> It also make easier and faster to find buffer and plane from using
>> the offset field.
>> Change __find_plane_by_offset() prototype to return the video buffer
>> itself rather than it index.
>>
>> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
>> ---
>>   .../media/common/videobuf2/videobuf2-core.c   | 73 +++++++++----------
>>   1 file changed, 35 insertions(+), 38 deletions(-)
>>
> Thanks a lot for working on this series. Just one comment inline.
>
>> diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
>> index a5e57affeb30..09be8e026044 100644
>> --- a/drivers/media/common/videobuf2/videobuf2-core.c
>> +++ b/drivers/media/common/videobuf2/videobuf2-core.c
>> @@ -31,6 +31,11 @@
>>   
>>   #include <trace/events/vb2.h>
>>   
>> +#define PLANE_INDEX_SHIFT	(PAGE_SHIFT + 3)
>> +#define PLANE_INDEX_MASK	0x7
> Could we somehow ensure that it indeed matches VIDEO_MAX_PLANES?
>
> One thing that comes to my mind would be
>
> #define PLANE_INDEX_BITS	3
> #define PLANE_INDEX_SHIFT	(PAGE_SHIFT + PLANE_INDEX_BITS)
> #define PLANE_INDEX_MASK	BIT_MASK(PLANE_INDEX_BITS)
>
> BUILD_BUG_ON(BIT(PLANE_INDEX_BITS) != VIDEO_MAX_PLANES);
>
> Alternatively we could change the videodev2.h, so that we have
>
> #define VIDEO_MAX_PLANES_BITS	3
> #define VIDEO_MAX_PLANES	(1U < VIDEO_MAX_PLANES_BITS)
>
> and then we can just VIDEO_MAX_PLANES_BITS in our definitions in this file
> and no checks would be necessary.

I would prefer this solution.
Hans should I do that in an other patch ?

Regards,
Benjamin

>
> Best regards,
> Tomasz
>
>> +#define MAX_BUFFER_INDEX	BIT_MASK(30 - PLANE_INDEX_SHIFT)
>> +#define BUFFER_INDEX_MASK	(MAX_BUFFER_INDEX - 1)
>> +
>>   static int debug;
>>   module_param(debug, int, 0644);
>>   
>> @@ -358,21 +363,27 @@ static void __setup_offsets(struct vb2_buffer *vb)
>>   	unsigned int plane;
>>   	unsigned long offset = 0;
>>   
>> -	if (vb->index) {
>> -		struct vb2_buffer *prev = q->bufs[vb->index - 1];
>> -		struct vb2_plane *p = &prev->planes[prev->num_planes - 1];
>> -
>> -		offset = PAGE_ALIGN(p->m.offset + p->length);
>> -	}
>> +	/*
>> +	 * The offset "cookie" value has the following constraints:
>> +	 * - a buffer can have up to 8 planes.
>> +	 * - v4l2 mem2mem uses bit 30 to distinguish between
>> +	 *   OUTPUT (aka "source", bit 30 is 0) and
>> +	 *   CAPTURE (aka "destination", bit 30 is 1) buffers.
>> +	 * - must be page aligned
>> +	 * That led to this bit mapping when PAGE_SHIFT = 12:
>> +	 * |30                |29        15|14       12|11 0|
>> +	 * |DST_QUEUE_OFF_BASE|buffer index|plane index| 0  |
>> +	 * where there are 15 bits to store the buffer index.
>> +	 * Depending on PAGE_SHIFT value we can have fewer bits
>> +	 * to store the buffer index.
>> +	 */
>> +	offset = vb->index << PLANE_INDEX_SHIFT;
>>   
>>   	for (plane = 0; plane < vb->num_planes; ++plane) {
>> -		vb->planes[plane].m.offset = offset;
>> +		vb->planes[plane].m.offset = offset + (plane << PAGE_SHIFT);
>>   
>>   		dprintk(q, 3, "buffer %d, plane %d offset 0x%08lx\n",
>>   				vb->index, plane, offset);
>> -
>> -		offset += vb->planes[plane].length;
>> -		offset = PAGE_ALIGN(offset);
>>   	}
>>   }
>>   
>> @@ -2188,10 +2199,9 @@ EXPORT_SYMBOL_GPL(vb2_core_streamoff);
>>    * __find_plane_by_offset() - find plane associated with the given offset
>>    */
>>   static int __find_plane_by_offset(struct vb2_queue *q, unsigned long offset,
>> -			unsigned int *_buffer, unsigned int *_plane)
>> +			struct vb2_buffer **vb, unsigned int *plane)
>>   {
>> -	struct vb2_buffer *vb;
>> -	unsigned int buffer, plane;
>> +	unsigned int buffer;
>>   
>>   	/*
>>   	 * Sanity checks to ensure the lock is held, MEMORY_MMAP is
>> @@ -2209,24 +2219,15 @@ static int __find_plane_by_offset(struct vb2_queue *q, unsigned long offset,
>>   		return -EBUSY;
>>   	}
>>   
>> -	/*
>> -	 * Go over all buffers and their planes, comparing the given offset
>> -	 * with an offset assigned to each plane. If a match is found,
>> -	 * return its buffer and plane numbers.
>> -	 */
>> -	for (buffer = 0; buffer < q->num_buffers; ++buffer) {
>> -		vb = q->bufs[buffer];
>> +	/* Get buffer and plane from the offset */
>> +	buffer = (offset >> PLANE_INDEX_SHIFT) & BUFFER_INDEX_MASK;
>> +	*plane = (offset >> PAGE_SHIFT) & PLANE_INDEX_MASK;
>>   
>> -		for (plane = 0; plane < vb->num_planes; ++plane) {
>> -			if (vb->planes[plane].m.offset == offset) {
>> -				*_buffer = buffer;
>> -				*_plane = plane;
>> -				return 0;
>> -			}
>> -		}
>> -	}
>> +	if (buffer >= q->num_buffers || *plane >= q->bufs[buffer]->num_planes)
>> +		return -EINVAL;
>>   
>> -	return -EINVAL;
>> +	*vb = q->bufs[buffer];
>> +	return 0;
>>   }
>>   
>>   int vb2_core_expbuf(struct vb2_queue *q, int *fd, unsigned int type,
>> @@ -2306,7 +2307,7 @@ int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma)
>>   {
>>   	unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
>>   	struct vb2_buffer *vb;
>> -	unsigned int buffer = 0, plane = 0;
>> +	unsigned int plane = 0;
>>   	int ret;
>>   	unsigned long length;
>>   
>> @@ -2335,12 +2336,10 @@ int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma)
>>   	 * Find the plane corresponding to the offset passed by userspace. This
>>   	 * will return an error if not MEMORY_MMAP or file I/O is in progress.
>>   	 */
>> -	ret = __find_plane_by_offset(q, offset, &buffer, &plane);
>> +	ret = __find_plane_by_offset(q, offset, &vb, &plane);
>>   	if (ret)
>>   		goto unlock;
>>   
>> -	vb = q->bufs[buffer];
>> -
>>   	/*
>>   	 * MMAP requires page_aligned buffers.
>>   	 * The buffer length was page_aligned at __vb2_buf_mem_alloc(),
>> @@ -2368,7 +2367,7 @@ int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma)
>>   	if (ret)
>>   		return ret;
>>   
>> -	dprintk(q, 3, "buffer %d, plane %d successfully mapped\n", buffer, plane);
>> +	dprintk(q, 3, "buffer %u, plane %d successfully mapped\n", vb->index, plane);
>>   	return 0;
>>   }
>>   EXPORT_SYMBOL_GPL(vb2_mmap);
>> @@ -2382,7 +2381,7 @@ unsigned long vb2_get_unmapped_area(struct vb2_queue *q,
>>   {
>>   	unsigned long offset = pgoff << PAGE_SHIFT;
>>   	struct vb2_buffer *vb;
>> -	unsigned int buffer, plane;
>> +	unsigned int plane;
>>   	void *vaddr;
>>   	int ret;
>>   
>> @@ -2392,12 +2391,10 @@ unsigned long vb2_get_unmapped_area(struct vb2_queue *q,
>>   	 * Find the plane corresponding to the offset passed by userspace. This
>>   	 * will return an error if not MEMORY_MMAP or file I/O is in progress.
>>   	 */
>> -	ret = __find_plane_by_offset(q, offset, &buffer, &plane);
>> +	ret = __find_plane_by_offset(q, offset, &vb, &plane);
>>   	if (ret)
>>   		goto unlock;
>>   
>> -	vb = q->bufs[buffer];
>> -
>>   	vaddr = vb2_plane_vaddr(vb, plane);
>>   	mutex_unlock(&q->mmap_lock);
>>   	return vaddr ? (unsigned long)vaddr : -EINVAL;
>> -- 
>> 2.39.2
>>
Hans Verkuil Nov. 8, 2023, 10:31 a.m. UTC | #3 
On 08/11/2023 11:14, Benjamin Gaignard wrote:
> 
> Le 08/11/2023 à 07:23, Tomasz Figa a écrit :
>> Hi Benjamin,
>>
>> On Tue, Oct 31, 2023 at 05:30:10PM +0100, Benjamin Gaignard wrote:
>>> Change how offset 'cookie' field value is computed to make possible
>>> to use more buffers.
>>> The maximum number of buffers depends of PAGE_SHIFT value and can
>>> go up to 0x7fff when PAGE_SHIFT = 12.
>>> With this encoding pattern we know the maximum number that a queue
>>> could store so we can check it at  queue init time.
>>> It also make easier and faster to find buffer and plane from using
>>> the offset field.
>>> Change __find_plane_by_offset() prototype to return the video buffer
>>> itself rather than it index.
>>>
>>> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
>>> ---
>>>   .../media/common/videobuf2/videobuf2-core.c   | 73 +++++++++----------
>>>   1 file changed, 35 insertions(+), 38 deletions(-)
>>>
>> Thanks a lot for working on this series. Just one comment inline.
>>
>>> diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
>>> index a5e57affeb30..09be8e026044 100644
>>> --- a/drivers/media/common/videobuf2/videobuf2-core.c
>>> +++ b/drivers/media/common/videobuf2/videobuf2-core.c
>>> @@ -31,6 +31,11 @@
>>>     #include <trace/events/vb2.h>
>>>   +#define PLANE_INDEX_SHIFT    (PAGE_SHIFT + 3)
>>> +#define PLANE_INDEX_MASK    0x7
>> Could we somehow ensure that it indeed matches VIDEO_MAX_PLANES?
>>
>> One thing that comes to my mind would be
>>
>> #define PLANE_INDEX_BITS    3
>> #define PLANE_INDEX_SHIFT    (PAGE_SHIFT + PLANE_INDEX_BITS)
>> #define PLANE_INDEX_MASK    BIT_MASK(PLANE_INDEX_BITS)
>>
>> BUILD_BUG_ON(BIT(PLANE_INDEX_BITS) != VIDEO_MAX_PLANES);
>>
>> Alternatively we could change the videodev2.h, so that we have
>>
>> #define VIDEO_MAX_PLANES_BITS    3
>> #define VIDEO_MAX_PLANES    (1U < VIDEO_MAX_PLANES_BITS)
>>
>> and then we can just VIDEO_MAX_PLANES_BITS in our definitions in this file
>> and no checks would be necessary.
> 
> I would prefer this solution.
> Hans should I do that in an other patch ?

I prefer to not make changes in videodev2.h, to be honest. I think it is fine to
just add a check in videobuf2-core.c.

Regards,

	Hans

> 
> Regards,
> Benjamin
> 
>>
>> Best regards,
>> Tomasz
>>
>>> +#define MAX_BUFFER_INDEX    BIT_MASK(30 - PLANE_INDEX_SHIFT)
>>> +#define BUFFER_INDEX_MASK    (MAX_BUFFER_INDEX - 1)
>>> +
>>>   static int debug;
>>>   module_param(debug, int, 0644);
>>>   @@ -358,21 +363,27 @@ static void __setup_offsets(struct vb2_buffer *vb)
>>>       unsigned int plane;
>>>       unsigned long offset = 0;
>>>   -    if (vb->index) {
>>> -        struct vb2_buffer *prev = q->bufs[vb->index - 1];
>>> -        struct vb2_plane *p = &prev->planes[prev->num_planes - 1];
>>> -
>>> -        offset = PAGE_ALIGN(p->m.offset + p->length);
>>> -    }
>>> +    /*
>>> +     * The offset "cookie" value has the following constraints:
>>> +     * - a buffer can have up to 8 planes.
>>> +     * - v4l2 mem2mem uses bit 30 to distinguish between
>>> +     *   OUTPUT (aka "source", bit 30 is 0) and
>>> +     *   CAPTURE (aka "destination", bit 30 is 1) buffers.
>>> +     * - must be page aligned
>>> +     * That led to this bit mapping when PAGE_SHIFT = 12:
>>> +     * |30                |29        15|14       12|11 0|
>>> +     * |DST_QUEUE_OFF_BASE|buffer index|plane index| 0  |
>>> +     * where there are 15 bits to store the buffer index.
>>> +     * Depending on PAGE_SHIFT value we can have fewer bits
>>> +     * to store the buffer index.
>>> +     */
>>> +    offset = vb->index << PLANE_INDEX_SHIFT;
>>>         for (plane = 0; plane < vb->num_planes; ++plane) {
>>> -        vb->planes[plane].m.offset = offset;
>>> +        vb->planes[plane].m.offset = offset + (plane << PAGE_SHIFT);
>>>             dprintk(q, 3, "buffer %d, plane %d offset 0x%08lx\n",
>>>                   vb->index, plane, offset);
>>> -
>>> -        offset += vb->planes[plane].length;
>>> -        offset = PAGE_ALIGN(offset);
>>>       }
>>>   }
>>>   @@ -2188,10 +2199,9 @@ EXPORT_SYMBOL_GPL(vb2_core_streamoff);
>>>    * __find_plane_by_offset() - find plane associated with the given offset
>>>    */
>>>   static int __find_plane_by_offset(struct vb2_queue *q, unsigned long offset,
>>> -            unsigned int *_buffer, unsigned int *_plane)
>>> +            struct vb2_buffer **vb, unsigned int *plane)
>>>   {
>>> -    struct vb2_buffer *vb;
>>> -    unsigned int buffer, plane;
>>> +    unsigned int buffer;
>>>         /*
>>>        * Sanity checks to ensure the lock is held, MEMORY_MMAP is
>>> @@ -2209,24 +2219,15 @@ static int __find_plane_by_offset(struct vb2_queue *q, unsigned long offset,
>>>           return -EBUSY;
>>>       }
>>>   -    /*
>>> -     * Go over all buffers and their planes, comparing the given offset
>>> -     * with an offset assigned to each plane. If a match is found,
>>> -     * return its buffer and plane numbers.
>>> -     */
>>> -    for (buffer = 0; buffer < q->num_buffers; ++buffer) {
>>> -        vb = q->bufs[buffer];
>>> +    /* Get buffer and plane from the offset */
>>> +    buffer = (offset >> PLANE_INDEX_SHIFT) & BUFFER_INDEX_MASK;
>>> +    *plane = (offset >> PAGE_SHIFT) & PLANE_INDEX_MASK;
>>>   -        for (plane = 0; plane < vb->num_planes; ++plane) {
>>> -            if (vb->planes[plane].m.offset == offset) {
>>> -                *_buffer = buffer;
>>> -                *_plane = plane;
>>> -                return 0;
>>> -            }
>>> -        }
>>> -    }
>>> +    if (buffer >= q->num_buffers || *plane >= q->bufs[buffer]->num_planes)
>>> +        return -EINVAL;
>>>   -    return -EINVAL;
>>> +    *vb = q->bufs[buffer];
>>> +    return 0;
>>>   }
>>>     int vb2_core_expbuf(struct vb2_queue *q, int *fd, unsigned int type,
>>> @@ -2306,7 +2307,7 @@ int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma)
>>>   {
>>>       unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
>>>       struct vb2_buffer *vb;
>>> -    unsigned int buffer = 0, plane = 0;
>>> +    unsigned int plane = 0;
>>>       int ret;
>>>       unsigned long length;
>>>   @@ -2335,12 +2336,10 @@ int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma)
>>>        * Find the plane corresponding to the offset passed by userspace. This
>>>        * will return an error if not MEMORY_MMAP or file I/O is in progress.
>>>        */
>>> -    ret = __find_plane_by_offset(q, offset, &buffer, &plane);
>>> +    ret = __find_plane_by_offset(q, offset, &vb, &plane);
>>>       if (ret)
>>>           goto unlock;
>>>   -    vb = q->bufs[buffer];
>>> -
>>>       /*
>>>        * MMAP requires page_aligned buffers.
>>>        * The buffer length was page_aligned at __vb2_buf_mem_alloc(),
>>> @@ -2368,7 +2367,7 @@ int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma)
>>>       if (ret)
>>>           return ret;
>>>   -    dprintk(q, 3, "buffer %d, plane %d successfully mapped\n", buffer, plane);
>>> +    dprintk(q, 3, "buffer %u, plane %d successfully mapped\n", vb->index, plane);
>>>       return 0;
>>>   }
>>>   EXPORT_SYMBOL_GPL(vb2_mmap);
>>> @@ -2382,7 +2381,7 @@ unsigned long vb2_get_unmapped_area(struct vb2_queue *q,
>>>   {
>>>       unsigned long offset = pgoff << PAGE_SHIFT;
>>>       struct vb2_buffer *vb;
>>> -    unsigned int buffer, plane;
>>> +    unsigned int plane;
>>>       void *vaddr;
>>>       int ret;
>>>   @@ -2392,12 +2391,10 @@ unsigned long vb2_get_unmapped_area(struct vb2_queue *q,
>>>        * Find the plane corresponding to the offset passed by userspace. This
>>>        * will return an error if not MEMORY_MMAP or file I/O is in progress.
>>>        */
>>> -    ret = __find_plane_by_offset(q, offset, &buffer, &plane);
>>> +    ret = __find_plane_by_offset(q, offset, &vb, &plane);
>>>       if (ret)
>>>           goto unlock;
>>>   -    vb = q->bufs[buffer];
>>> -
>>>       vaddr = vb2_plane_vaddr(vb, plane);
>>>       mutex_unlock(&q->mmap_lock);
>>>       return vaddr ? (unsigned long)vaddr : -EINVAL;
>>> -- 
>>> 2.39.2
>>>
diff mbox series

Patch

diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
index a5e57affeb30..09be8e026044 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -31,6 +31,11 @@ 
 
 #include <trace/events/vb2.h>
 
+#define PLANE_INDEX_SHIFT	(PAGE_SHIFT + 3)
+#define PLANE_INDEX_MASK	0x7
+#define MAX_BUFFER_INDEX	BIT_MASK(30 - PLANE_INDEX_SHIFT)
+#define BUFFER_INDEX_MASK	(MAX_BUFFER_INDEX - 1)
+
 static int debug;
 module_param(debug, int, 0644);
 
@@ -358,21 +363,27 @@  static void __setup_offsets(struct vb2_buffer *vb)
 	unsigned int plane;
 	unsigned long offset = 0;
 
-	if (vb->index) {
-		struct vb2_buffer *prev = q->bufs[vb->index - 1];
-		struct vb2_plane *p = &prev->planes[prev->num_planes - 1];
-
-		offset = PAGE_ALIGN(p->m.offset + p->length);
-	}
+	/*
+	 * The offset "cookie" value has the following constraints:
+	 * - a buffer can have up to 8 planes.
+	 * - v4l2 mem2mem uses bit 30 to distinguish between
+	 *   OUTPUT (aka "source", bit 30 is 0) and
+	 *   CAPTURE (aka "destination", bit 30 is 1) buffers.
+	 * - must be page aligned
+	 * That led to this bit mapping when PAGE_SHIFT = 12:
+	 * |30                |29        15|14       12|11 0|
+	 * |DST_QUEUE_OFF_BASE|buffer index|plane index| 0  |
+	 * where there are 15 bits to store the buffer index.
+	 * Depending on PAGE_SHIFT value we can have fewer bits
+	 * to store the buffer index.
+	 */
+	offset = vb->index << PLANE_INDEX_SHIFT;
 
 	for (plane = 0; plane < vb->num_planes; ++plane) {
-		vb->planes[plane].m.offset = offset;
+		vb->planes[plane].m.offset = offset + (plane << PAGE_SHIFT);
 
 		dprintk(q, 3, "buffer %d, plane %d offset 0x%08lx\n",
 				vb->index, plane, offset);
-
-		offset += vb->planes[plane].length;
-		offset = PAGE_ALIGN(offset);
 	}
 }
 
@@ -2188,10 +2199,9 @@  EXPORT_SYMBOL_GPL(vb2_core_streamoff);
  * __find_plane_by_offset() - find plane associated with the given offset
  */
 static int __find_plane_by_offset(struct vb2_queue *q, unsigned long offset,
-			unsigned int *_buffer, unsigned int *_plane)
+			struct vb2_buffer **vb, unsigned int *plane)
 {
-	struct vb2_buffer *vb;
-	unsigned int buffer, plane;
+	unsigned int buffer;
 
 	/*
 	 * Sanity checks to ensure the lock is held, MEMORY_MMAP is
@@ -2209,24 +2219,15 @@  static int __find_plane_by_offset(struct vb2_queue *q, unsigned long offset,
 		return -EBUSY;
 	}
 
-	/*
-	 * Go over all buffers and their planes, comparing the given offset
-	 * with an offset assigned to each plane. If a match is found,
-	 * return its buffer and plane numbers.
-	 */
-	for (buffer = 0; buffer < q->num_buffers; ++buffer) {
-		vb = q->bufs[buffer];
+	/* Get buffer and plane from the offset */
+	buffer = (offset >> PLANE_INDEX_SHIFT) & BUFFER_INDEX_MASK;
+	*plane = (offset >> PAGE_SHIFT) & PLANE_INDEX_MASK;
 
-		for (plane = 0; plane < vb->num_planes; ++plane) {
-			if (vb->planes[plane].m.offset == offset) {
-				*_buffer = buffer;
-				*_plane = plane;
-				return 0;
-			}
-		}
-	}
+	if (buffer >= q->num_buffers || *plane >= q->bufs[buffer]->num_planes)
+		return -EINVAL;
 
-	return -EINVAL;
+	*vb = q->bufs[buffer];
+	return 0;
 }
 
 int vb2_core_expbuf(struct vb2_queue *q, int *fd, unsigned int type,
@@ -2306,7 +2307,7 @@  int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma)
 {
 	unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
 	struct vb2_buffer *vb;
-	unsigned int buffer = 0, plane = 0;
+	unsigned int plane = 0;
 	int ret;
 	unsigned long length;
 
@@ -2335,12 +2336,10 @@  int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma)
 	 * Find the plane corresponding to the offset passed by userspace. This
 	 * will return an error if not MEMORY_MMAP or file I/O is in progress.
 	 */
-	ret = __find_plane_by_offset(q, offset, &buffer, &plane);
+	ret = __find_plane_by_offset(q, offset, &vb, &plane);
 	if (ret)
 		goto unlock;
 
-	vb = q->bufs[buffer];
-
 	/*
 	 * MMAP requires page_aligned buffers.
 	 * The buffer length was page_aligned at __vb2_buf_mem_alloc(),
@@ -2368,7 +2367,7 @@  int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma)
 	if (ret)
 		return ret;
 
-	dprintk(q, 3, "buffer %d, plane %d successfully mapped\n", buffer, plane);
+	dprintk(q, 3, "buffer %u, plane %d successfully mapped\n", vb->index, plane);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(vb2_mmap);
@@ -2382,7 +2381,7 @@  unsigned long vb2_get_unmapped_area(struct vb2_queue *q,
 {
 	unsigned long offset = pgoff << PAGE_SHIFT;
 	struct vb2_buffer *vb;
-	unsigned int buffer, plane;
+	unsigned int plane;
 	void *vaddr;
 	int ret;
 
@@ -2392,12 +2391,10 @@  unsigned long vb2_get_unmapped_area(struct vb2_queue *q,
 	 * Find the plane corresponding to the offset passed by userspace. This
 	 * will return an error if not MEMORY_MMAP or file I/O is in progress.
 	 */
-	ret = __find_plane_by_offset(q, offset, &buffer, &plane);
+	ret = __find_plane_by_offset(q, offset, &vb, &plane);
 	if (ret)
 		goto unlock;
 
-	vb = q->bufs[buffer];
-
 	vaddr = vb2_plane_vaddr(vb, plane);
 	mutex_unlock(&q->mmap_lock);
 	return vaddr ? (unsigned long)vaddr : -EINVAL;