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To: Thomas Monjalon <thomas@monjalon.net>
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References: <1625231891-2963-1-git-send-email-fengchengwen@huawei.com>
<20210924105357.15386-1-fengchengwen@huawei.com>
<20210924105357.15386-3-fengchengwen@huawei.com> <11425429.3DvE4F450j@thomas>
From: fengchengwen <fengchengwen@huawei.com>
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Subject: Re: [dpdk-dev] [PATCH v23 2/6] dmadev: add control plane function
support
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On 2021/10/6 18:46, Thomas Monjalon wrote:
> 24/09/2021 12:53, Chengwen Feng:
>> --- a/doc/guides/prog_guide/dmadev.rst
>> +++ b/doc/guides/prog_guide/dmadev.rst
>> @@ -62,3 +62,44 @@ identifiers:
>>
>> - A device name used to designate the DMA device in console messages, for
>> administration or debugging purposes.
[snip]
>
>> --- a/lib/dmadev/rte_dmadev.c
>> +++ b/lib/dmadev/rte_dmadev.c
>> @@ -218,6 +218,9 @@ rte_dma_pmd_release(const char *name)
>> if (dev == NULL)
>> return -EINVAL;
>>
>> + if (dev->state == RTE_DMA_DEV_READY)
>> + return rte_dma_close(dev->dev_id);
>
> What is the logic here?
> The only exposed function should be rte_dma_close()
> and it should call the freeing function.
> The API should use the dev_id. As you said somewhere else,
> the name is only for debugging.
> Please remove the function rte_dma_pmd_release(const char *name).
The rte_dma_pmd_release corresponding to pmd_allocate, so both use the 'const char *name' parameter.
The rte_dma_pmd_release is also used for error handling when PMD init. Therefore, a status variable
is used here. If the device is not ready, only resources need to be released. Otherwise, the close
interface of the driver is invoked.
For PMD, the rte_dma_pmd_release is only wrap for dev_close when remove device, it does not need to
implement two callbacks.
If we replace rte_dma_pmd_release with rte_dma_close, then we should invoke rte_dma_close in error
handling when PMD init, this can lead to conceptual inconsistencies because the initialization has
not been successful.
So I think it's better keep rte_dma_pmd_release.
>
> [...]
>> --- a/lib/dmadev/rte_dmadev.h
>> +++ b/lib/dmadev/rte_dmadev.h
>> + * The functions exported by the dmadev API to setup a device designated by its
>> + * device identifier must be invoked in the following order:
>> + * - rte_dma_configure()
>> + * - rte_dma_vchan_setup()
>> + * - rte_dma_start()
>> + *
>> + * If the application wants to change the configuration (i.e. invoke
>> + * rte_dma_configure() or rte_dma_vchan_setup()), it must invoke
>> + * rte_dma_stop() first to stop the device and then do the reconfiguration
>> + * before invoking rte_dma_start() again. The dataplane functions should not
>> + * be invoked when the device is stopped.
>> + *
>> + * Finally, an application can close a dmadev by invoking the rte_dma_close()
>> + * function.
>
> Yes rte_dma_close, not rte_dma_pmd_release.
>
>> + *
>> + * About MT-safe, all the functions of the dmadev API exported by a PMD are
>
> API is not exported by a PMD, but implemented.
>
>> + * lock-free functions which assume to not be invoked in parallel on different
>> + * logical cores to work on the same target dmadev object.
>> + * @note Different virtual DMA channels on the same dmadev *DO NOT* support
>> + * parallel invocation because these virtual DMA channels share the same
>> + * HW-DMA-channel.
>> + *
>> */
>
> No need of final blank line in a comment.
>
>> +/** DMA device support memory-to-memory transfer.
>> + *
>> + * @see struct rte_dma_info::dev_capa
>> + */
>> +#define RTE_DMA_CAPA_MEM_TO_MEM RTE_BIT64(0)
>> +/** DMA device support memory-to-device transfer.
>> + *
>> + * @see struct rte_dma_info::dev_capa
>> + */
>> +#define RTE_DMA_CAPA_MEM_TO_DEV RTE_BIT64(1)
>
> Same comment as in earlier version: please group the flags
> in a doxygen group. Example of doxygen group:
> https://patches.dpdk.org/project/dpdk/patch/20210830104232.598703-1-thomas@monjalon.net/
Tried, but found it didn't coexist well with multi-line comments.
>
> [...]
> You are using uint64_t bitfields and anonymous union in below struct,
> it may not compile if not using __extension__ from RTE_STD_C11.
>
>> +struct rte_dma_port_param {
>> + /** The device access port type.
>> + *
>> + * @see enum rte_dma_port_type
>> + */
>> + enum rte_dma_port_type port_type;
>> + union {
> [...]
>> + struct {
>> + uint64_t coreid : 4; /**< PCIe core id used. */
>> + uint64_t pfid : 8; /**< PF id used. */
>> + uint64_t vfen : 1; /**< VF enable bit. */
>> + uint64_t vfid : 16; /**< VF id used. */
>> + /** The pasid filed in TLP packet. */
>> + uint64_t pasid : 20;
>> + /** The attributes filed in TLP packet. */
>> + uint64_t attr : 3;
>> + /** The processing hint filed in TLP packet. */
>> + uint64_t ph : 2;
>> + /** The steering tag filed in TLP packet. */
>> + uint64_t st : 16;
>> + } pcie;
>> + };
>> + uint64_t reserved[2]; /**< Reserved for future fields. */
>> +};
>
>> --- a/lib/dmadev/rte_dmadev_core.h
>> +++ b/lib/dmadev/rte_dmadev_core.h
>> +/** @internal Used to get device information of a device. */
>> +typedef int (*rte_dma_info_get_t)(const struct rte_dma_dev *dev,
>> + struct rte_dma_info *dev_info,
>> + uint32_t info_sz);
>
> Please move all driver interfaces in a file dedicated to drivers.
There are three head file: rte_dmadev.h, rte_dmadev_core.h, rte_dmadev_pmd.h
And we build the following dependency:
rte_dmadev.h ---> rte_dmadev_core.h // mainly because dataplane inline API.
^
|
---------------------
| |
Application rte_dmadev_pmd.h
^
|
DMA PMD
If move all driver interfaces to rte_dmadev_pmd.h from rte_dmadev_core.h, bidirectional
dependency may exist, e.g.
rte_dmadev.h ---> rte_dmadev_core.h ---> rte_dmadev_pmd.h
^
|
---------------------
| |
Application rte_dmadev_pmd.h
^
|
DMA PMD
So I think it's better keep it that way.
>
> [...]
>> @@ -40,9 +96,13 @@ struct rte_dma_dev {
>> int16_t dev_id; /**< Device [external] identifier. */
>> int16_t numa_node; /**< Local NUMA memory ID. -1 if unknown. */
>> void *dev_private; /**< PMD-specific private data. */
>> + /** Functions exported by PMD. */
>
> s/exported/implemented/
>
>> + const struct rte_dma_dev_ops *dev_ops;
>> + struct rte_dma_conf dev_conf; /**< DMA device configuration. */
>> /** Device info which supplied during device initialization. */
>> struct rte_device *device;
>> enum rte_dma_dev_state state; /**< Flag indicating the device state. */
>> + uint8_t dev_started : 1; /**< Device state: STARTED(1)/STOPPED(0). */
>> uint64_t reserved[2]; /**< Reserved for future fields. */
>> } __rte_cache_aligned;
>
>
>
>
> .
>
Thanks