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Message-ID: <3175d41a-fc44-4741-91ac-005c8f21abb8@vivo.com>
Date: Sun, 7 Apr 2024 15:50:10 +0800
From: Rong Qianfeng <rongqianfeng@...o.com>
To: Christian König <christian.koenig@....com>,
Jianqun Xu <jay.xu@...k-chips.com>, sumit.semwal@...aro.org
Cc: pekka.paalanen@...labora.com, daniel.vetter@...ll.ch,
jason@...kstrand.net, linux-media@...r.kernel.org,
dri-devel@...ts.freedesktop.org, linaro-mm-sig@...ts.linaro.org,
linux-kernel@...r.kernel.org, linux-rockchip@...ts.infradead.org
Subject: Re: [PATCH] dma-buf: add DMA_BUF_IOCTL_SYNC_PARTIAL support
在 2021/11/15 19:42, Christian König 写道:
> Am 13.11.21 um 07:22 schrieb Jianqun Xu:
>> Add DMA_BUF_IOCTL_SYNC_PARTIAL support for user to sync dma-buf with
>> offset and len.
>
> You have not given an use case for this so it is a bit hard to review.
> And from the existing use cases I don't see why this should be necessary.
>
> Even worse from the existing backend implementation I don't even see
> how drivers should be able to fulfill this semantics.
>
> Please explain further,
> Christian.
>
>>
>> Change-Id: I03d2d2e10e48d32aa83c31abade57e0931e1be49
>> Signed-off-by: Jianqun Xu <jay.xu@...k-chips.com>
>> ---
>> drivers/dma-buf/dma-buf.c | 42 ++++++++++++++++++++++++++++++++++++
>> include/uapi/linux/dma-buf.h | 8 +++++++
>> 2 files changed, 50 insertions(+)
>>
>> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
>> index d9948d58b3f4..78f37f7c3462 100644
>> --- a/drivers/dma-buf/dma-buf.c
>> +++ b/drivers/dma-buf/dma-buf.c
>> @@ -392,6 +392,7 @@ static long dma_buf_ioctl(struct file *file,
>> {
>> struct dma_buf *dmabuf;
>> struct dma_buf_sync sync;
>> + struct dma_buf_sync_partial sync_p;
>> enum dma_data_direction direction;
>> int ret;
>> @@ -430,6 +431,47 @@ static long dma_buf_ioctl(struct file *file,
>> case DMA_BUF_SET_NAME_B:
>> return dma_buf_set_name(dmabuf, (const char __user *)arg);
>> + case DMA_BUF_IOCTL_SYNC_PARTIAL:
>> + if (copy_from_user(&sync_p, (void __user *) arg,
>> sizeof(sync_p)))
>> + return -EFAULT;
>> +
>> + if (sync_p.len == 0)
>> + return 0;
>> +
>> + if ((sync_p.offset % cache_line_size()) || (sync_p.len %
>> cache_line_size()))
>> + return -EINVAL;
>> +
>> + if (sync_p.len > dmabuf->size || sync_p.offset >
>> dmabuf->size - sync_p.len)
>> + return -EINVAL;
>> +
>> + if (sync_p.flags & ~DMA_BUF_SYNC_VALID_FLAGS_MASK)
>> + return -EINVAL;
>> +
>> + switch (sync_p.flags & DMA_BUF_SYNC_RW) {
>> + case DMA_BUF_SYNC_READ:
>> + direction = DMA_FROM_DEVICE;
>> + break;
>> + case DMA_BUF_SYNC_WRITE:
>> + direction = DMA_TO_DEVICE;
>> + break;
>> + case DMA_BUF_SYNC_RW:
>> + direction = DMA_BIDIRECTIONAL;
>> + break;
>> + default:
>> + return -EINVAL;
>> + }
>> +
>> + if (sync_p.flags & DMA_BUF_SYNC_END)
>> + ret = dma_buf_end_cpu_access_partial(dmabuf, direction,
>> + sync_p.offset,
>> + sync_p.len);
>> + else
>> + ret = dma_buf_begin_cpu_access_partial(dmabuf, direction,
>> + sync_p.offset,
>> + sync_p.len);
>> +
>> + return ret;
>> +
>> default:
>> return -ENOTTY;
>> }
>> diff --git a/include/uapi/linux/dma-buf.h b/include/uapi/linux/dma-buf.h
>> index 7f30393b92c3..6236c644624d 100644
>> --- a/include/uapi/linux/dma-buf.h
>> +++ b/include/uapi/linux/dma-buf.h
>> @@ -47,4 +47,12 @@ struct dma_buf_sync {
>> #define DMA_BUF_SET_NAME_A _IOW(DMA_BUF_BASE, 1, u32)
>> #define DMA_BUF_SET_NAME_B _IOW(DMA_BUF_BASE, 1, u64)
>> +struct dma_buf_sync_partial {
>> + __u64 flags;
>> + __u32 offset;
>> + __u32 len;
>> +};
>> +
>> +#define DMA_BUF_IOCTL_SYNC_PARTIAL _IOW(DMA_BUF_BASE, 2, struct
>> dma_buf_sync_partial)
>> +
>> #endif
>
>
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> Subject: Re: [PATCH] dma-buf: add DMA_BUF_IOCTL_SYNC_PARTIAL support
> To: Jianqun Xu <jay.xu@...k-chips.com>, sumit.semwal@...aro.org
> References: <20211113062222.3743909-1-jay.xu@...k-chips.com>
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> linaro-mm-sig@...ts.linaro.org, linux-rockchip@...ts.infradead.org,
> jason@...kstrand.net, linux-media@...r.kernel.org
> Errors-To: dri-devel-bounces@...ts.freedesktop.org
> Sender: "dri-devel" <dri-devel-bounces@...ts.freedesktop.org>
>
> Am 13.11.21 um 07:22 schrieb Jianqun Xu:
>> Add DMA_BUF_IOCTL_SYNC_PARTIAL support for user to sync dma-buf with
>> offset and len.
>
> You have not given an use case for this so it is a bit hard to review.
> And from the existing use cases I don't see why this should be necessary.
>
> Even worse from the existing backend implementation I don't even see
> how drivers should be able to fulfill this semantics.
>
> Please explain further,
> Christian.
>
>>
>> Change-Id: I03d2d2e10e48d32aa83c31abade57e0931e1be49
>> Signed-off-by: Jianqun Xu <jay.xu@...k-chips.com>
>> ---
>> drivers/dma-buf/dma-buf.c | 42 ++++++++++++++++++++++++++++++++++++
>> include/uapi/linux/dma-buf.h | 8 +++++++
>> 2 files changed, 50 insertions(+)
>>
>> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
>> index d9948d58b3f4..78f37f7c3462 100644
>> --- a/drivers/dma-buf/dma-buf.c
>> +++ b/drivers/dma-buf/dma-buf.c
>> @@ -392,6 +392,7 @@ static long dma_buf_ioctl(struct file *file,
>> {
>> struct dma_buf *dmabuf;
>> struct dma_buf_sync sync;
>> + struct dma_buf_sync_partial sync_p;
>> enum dma_data_direction direction;
>> int ret;
>> @@ -430,6 +431,47 @@ static long dma_buf_ioctl(struct file *file,
>> case DMA_BUF_SET_NAME_B:
>> return dma_buf_set_name(dmabuf, (const char __user *)arg);
>> + case DMA_BUF_IOCTL_SYNC_PARTIAL:
>> + if (copy_from_user(&sync_p, (void __user *) arg,
>> sizeof(sync_p)))
>> + return -EFAULT;
>> +
>> + if (sync_p.len == 0)
>> + return 0;
>> +
>> + if ((sync_p.offset % cache_line_size()) || (sync_p.len %
>> cache_line_size()))
>> + return -EINVAL;
>> +
>> + if (sync_p.len > dmabuf->size || sync_p.offset >
>> dmabuf->size - sync_p.len)
>> + return -EINVAL;
>> +
>> + if (sync_p.flags & ~DMA_BUF_SYNC_VALID_FLAGS_MASK)
>> + return -EINVAL;
>> +
>> + switch (sync_p.flags & DMA_BUF_SYNC_RW) {
>> + case DMA_BUF_SYNC_READ:
>> + direction = DMA_FROM_DEVICE;
>> + break;
>> + case DMA_BUF_SYNC_WRITE:
>> + direction = DMA_TO_DEVICE;
>> + break;
>> + case DMA_BUF_SYNC_RW:
>> + direction = DMA_BIDIRECTIONAL;
>> + break;
>> + default:
>> + return -EINVAL;
>> + }
>> +
>> + if (sync_p.flags & DMA_BUF_SYNC_END)
>> + ret = dma_buf_end_cpu_access_partial(dmabuf, direction,
>> + sync_p.offset,
>> + sync_p.len);
>> + else
>> + ret = dma_buf_begin_cpu_access_partial(dmabuf, direction,
>> + sync_p.offset,
>> + sync_p.len);
>> +
>> + return ret;
>> +
>> default:
>> return -ENOTTY;
>> }
>> diff --git a/include/uapi/linux/dma-buf.h b/include/uapi/linux/dma-buf.h
>> index 7f30393b92c3..6236c644624d 100644
>> --- a/include/uapi/linux/dma-buf.h
>> +++ b/include/uapi/linux/dma-buf.h
>> @@ -47,4 +47,12 @@ struct dma_buf_sync {
>> #define DMA_BUF_SET_NAME_A _IOW(DMA_BUF_BASE, 1, u32)
>> #define DMA_BUF_SET_NAME_B _IOW(DMA_BUF_BASE, 1, u64)
>> +struct dma_buf_sync_partial {
>> + __u64 flags;
>> + __u32 offset;
>> + __u32 len;
>> +};
>> +
>> +#define DMA_BUF_IOCTL_SYNC_PARTIAL _IOW(DMA_BUF_BASE, 2, struct
>> dma_buf_sync_partial)
>> +
>> #endif
>
>
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> Subject: Re: [PATCH] dma-buf: add DMA_BUF_IOCTL_SYNC_PARTIAL support
> To: Jianqun Xu <jay.xu@...k-chips.com>, sumit.semwal@...aro.org
> Cc: pekka.paalanen@...labora.com, daniel.vetter@...ll.ch,
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> References: <20211113062222.3743909-1-jay.xu@...k-chips.com>
> From: =?UTF-8?Q?Christian_K=c3=b6nig?= <christian.koenig@....com>
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> Am 13.11.21 um 07:22 schrieb Jianqun Xu:
>> Add DMA_BUF_IOCTL_SYNC_PARTIAL support for user to sync dma-buf with
>> offset and len.
>
> You have not given an use case for this so it is a bit hard to review.
> And from the existing use cases I don't see why this should be necessary.
>
> Even worse from the existing backend implementation I don't even see
> how drivers should be able to fulfill this semantics.
>
> Please explain further,
> Christian.
Here is a practical case:
The user space can allocate a large chunk of dma-buf for
self-management, used as a shared memory pool.
Small dma-buf can be allocated from this shared memory pool and released
back to it after use, thus improving the speed of dma-buf allocation and
release.
Additionally, custom functionalities such as memory statistics and
boundary checking can be implemented in the user space.
Of course, the above-mentioned functionalities require the
implementation of a partial cache sync interface.
Thanks
Rong Qianfeng.
>
>>
>> Change-Id: I03d2d2e10e48d32aa83c31abade57e0931e1be49
>> Signed-off-by: Jianqun Xu <jay.xu@...k-chips.com>
>> ---
>> drivers/dma-buf/dma-buf.c | 42 ++++++++++++++++++++++++++++++++++++
>> include/uapi/linux/dma-buf.h | 8 +++++++
>> 2 files changed, 50 insertions(+)
>>
>> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
>> index d9948d58b3f4..78f37f7c3462 100644
>> --- a/drivers/dma-buf/dma-buf.c
>> +++ b/drivers/dma-buf/dma-buf.c
>> @@ -392,6 +392,7 @@ static long dma_buf_ioctl(struct file *file,
>> {
>> struct dma_buf *dmabuf;
>> struct dma_buf_sync sync;
>> + struct dma_buf_sync_partial sync_p;
>> enum dma_data_direction direction;
>> int ret;
>> @@ -430,6 +431,47 @@ static long dma_buf_ioctl(struct file *file,
>> case DMA_BUF_SET_NAME_B:
>> return dma_buf_set_name(dmabuf, (const char __user *)arg);
>> + case DMA_BUF_IOCTL_SYNC_PARTIAL:
>> + if (copy_from_user(&sync_p, (void __user *) arg,
>> sizeof(sync_p)))
>> + return -EFAULT;
>> +
>> + if (sync_p.len == 0)
>> + return 0;
>> +
>> + if ((sync_p.offset % cache_line_size()) || (sync_p.len %
>> cache_line_size()))
>> + return -EINVAL;
>> +
>> + if (sync_p.len > dmabuf->size || sync_p.offset >
>> dmabuf->size - sync_p.len)
>> + return -EINVAL;
>> +
>> + if (sync_p.flags & ~DMA_BUF_SYNC_VALID_FLAGS_MASK)
>> + return -EINVAL;
>> +
>> + switch (sync_p.flags & DMA_BUF_SYNC_RW) {
>> + case DMA_BUF_SYNC_READ:
>> + direction = DMA_FROM_DEVICE;
>> + break;
>> + case DMA_BUF_SYNC_WRITE:
>> + direction = DMA_TO_DEVICE;
>> + break;
>> + case DMA_BUF_SYNC_RW:
>> + direction = DMA_BIDIRECTIONAL;
>> + break;
>> + default:
>> + return -EINVAL;
>> + }
>> +
>> + if (sync_p.flags & DMA_BUF_SYNC_END)
>> + ret = dma_buf_end_cpu_access_partial(dmabuf, direction,
>> + sync_p.offset,
>> + sync_p.len);
>> + else
>> + ret = dma_buf_begin_cpu_access_partial(dmabuf, direction,
>> + sync_p.offset,
>> + sync_p.len);
>> +
>> + return ret;
>> +
>> default:
>> return -ENOTTY;
>> }
>> diff --git a/include/uapi/linux/dma-buf.h b/include/uapi/linux/dma-buf.h
>> index 7f30393b92c3..6236c644624d 100644
>> --- a/include/uapi/linux/dma-buf.h
>> +++ b/include/uapi/linux/dma-buf.h
>> @@ -47,4 +47,12 @@ struct dma_buf_sync {
>> #define DMA_BUF_SET_NAME_A _IOW(DMA_BUF_BASE, 1, u32)
>> #define DMA_BUF_SET_NAME_B _IOW(DMA_BUF_BASE, 1, u64)
>> +struct dma_buf_sync_partial {
>> + __u64 flags;
>> + __u32 offset;
>> + __u32 len;
>> +};
>> +
>> +#define DMA_BUF_IOCTL_SYNC_PARTIAL _IOW(DMA_BUF_BASE, 2, struct
>> dma_buf_sync_partial)
>> +
>> #endif
>
>
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