[PATCH] dmaengine: remove DMA_MEMCPY_SG once again
Adrian Larumbe
adrianml at alumnos.upm.es
Mon Jun 6 12:54:55 PDT 2022
>On 06.06.2022 23:23, Vinod Koul wrote:
>On 06-06-22, 09:47, Christoph Hellwig wrote:
>> This was removed before due to the complete lack of users, but
>> 3218910fd585 ("dmaengine: Add core function and capability check for
>> DMA_MEMCPY_SG") and 29cf37fa6dd9 ("dmaengine: Add consumer for the new
>> DMA_MEMCPY_SG API function.") added it back despite still not having
>> any users whatsoever.
>>
>> Fixes: 3218910fd585 ("dmaengine: Add core function and capability check for DMA_MEMCPY_SG")
>> Fixes: 29cf37fa6dd9 ("dmaengine: Add consumer for the new DMA_MEMCPY_SG API function.")
>
>This is consumer of the driver API and it was bought back with the
>premise that user will also come...
It's commit 29cf37fa6dd9 ("dmaengine: Add consumer for the new DMA_MEMCPY_SG API function.")
The two previous commits add the new driver API callback and document it.
>Adrianm, Michal any reason why user is not mainline yet..?
Just double checked the mainline, and all three commits are there.
>> Signed-off-by: Christoph Hellwig <hch at lst.de>
>> ---
>> .../driver-api/dmaengine/provider.rst | 10 --
>> drivers/dma/dmaengine.c | 7 -
>> drivers/dma/xilinx/xilinx_dma.c | 122 ------------------
>> include/linux/dmaengine.h | 20 ---
>> 4 files changed, 159 deletions(-)
>>
>> diff --git a/Documentation/driver-api/dmaengine/provider.rst b/Documentation/driver-api/dmaengine/provider.rst
>> index 1e0f1f85d10e5..ceac2a300e328 100644
>> --- a/Documentation/driver-api/dmaengine/provider.rst
>> +++ b/Documentation/driver-api/dmaengine/provider.rst
>> @@ -162,16 +162,6 @@ Currently, the types available are:
>>
>> - The device is able to do memory to memory copies
>>
>> -- - DMA_MEMCPY_SG
>> -
>> - - The device supports memory to memory scatter-gather transfers.
>> -
>> - - Even though a plain memcpy can look like a particular case of a
>> - scatter-gather transfer, with a single chunk to copy, it's a distinct
>> - transaction type in the mem2mem transfer case. This is because some very
>> - simple devices might be able to do contiguous single-chunk memory copies,
>> - but have no support for more complex SG transfers.
>> -
>> - No matter what the overall size of the combined chunks for source and
>> destination is, only as many bytes as the smallest of the two will be
>> transmitted. That means the number and size of the scatter-gather buffers in
>> diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
>> index e80feeea0e018..c741b6431958c 100644
>> --- a/drivers/dma/dmaengine.c
>> +++ b/drivers/dma/dmaengine.c
>> @@ -1153,13 +1153,6 @@ int dma_async_device_register(struct dma_device *device)
>> return -EIO;
>> }
>>
>> - if (dma_has_cap(DMA_MEMCPY_SG, device->cap_mask) && !device->device_prep_dma_memcpy_sg) {
>> - dev_err(device->dev,
>> - "Device claims capability %s, but op is not defined\n",
>> - "DMA_MEMCPY_SG");
>> - return -EIO;
>> - }
>> -
>> if (dma_has_cap(DMA_XOR, device->cap_mask) && !device->device_prep_dma_xor) {
>> dev_err(device->dev,
>> "Device claims capability %s, but op is not defined\n",
>> diff --git a/drivers/dma/xilinx/xilinx_dma.c b/drivers/dma/xilinx/xilinx_dma.c
>> index cd62bbb50e8b4..6276934d4d2be 100644
>> --- a/drivers/dma/xilinx/xilinx_dma.c
>> +++ b/drivers/dma/xilinx/xilinx_dma.c
>> @@ -2127,126 +2127,6 @@ xilinx_cdma_prep_memcpy(struct dma_chan *dchan, dma_addr_t dma_dst,
>> return NULL;
>> }
>>
>> -/**
>> - * xilinx_cdma_prep_memcpy_sg - prepare descriptors for a memcpy_sg transaction
>> - * @dchan: DMA channel
>> - * @dst_sg: Destination scatter list
>> - * @dst_sg_len: Number of entries in destination scatter list
>> - * @src_sg: Source scatter list
>> - * @src_sg_len: Number of entries in source scatter list
>> - * @flags: transfer ack flags
>> - *
>> - * Return: Async transaction descriptor on success and NULL on failure
>> - */
>> -static struct dma_async_tx_descriptor *xilinx_cdma_prep_memcpy_sg(
>> - struct dma_chan *dchan, struct scatterlist *dst_sg,
>> - unsigned int dst_sg_len, struct scatterlist *src_sg,
>> - unsigned int src_sg_len, unsigned long flags)
>> -{
>> - struct xilinx_dma_chan *chan = to_xilinx_chan(dchan);
>> - struct xilinx_dma_tx_descriptor *desc;
>> - struct xilinx_cdma_tx_segment *segment, *prev = NULL;
>> - struct xilinx_cdma_desc_hw *hw;
>> - size_t len, dst_avail, src_avail;
>> - dma_addr_t dma_dst, dma_src;
>> -
>> - if (unlikely(dst_sg_len == 0 || src_sg_len == 0))
>> - return NULL;
>> -
>> - if (unlikely(!dst_sg || !src_sg))
>> - return NULL;
>> -
>> - desc = xilinx_dma_alloc_tx_descriptor(chan);
>> - if (!desc)
>> - return NULL;
>> -
>> - dma_async_tx_descriptor_init(&desc->async_tx, &chan->common);
>> - desc->async_tx.tx_submit = xilinx_dma_tx_submit;
>> -
>> - dst_avail = sg_dma_len(dst_sg);
>> - src_avail = sg_dma_len(src_sg);
>> - /*
>> - * loop until there is either no more source or no more destination
>> - * scatterlist entry
>> - */
>> - while (true) {
>> - len = min_t(size_t, src_avail, dst_avail);
>> - len = min_t(size_t, len, chan->xdev->max_buffer_len);
>> - if (len == 0)
>> - goto fetch;
>> -
>> - /* Allocate the link descriptor from DMA pool */
>> - segment = xilinx_cdma_alloc_tx_segment(chan);
>> - if (!segment)
>> - goto error;
>> -
>> - dma_dst = sg_dma_address(dst_sg) + sg_dma_len(dst_sg) -
>> - dst_avail;
>> - dma_src = sg_dma_address(src_sg) + sg_dma_len(src_sg) -
>> - src_avail;
>> - hw = &segment->hw;
>> - hw->control = len;
>> - hw->src_addr = dma_src;
>> - hw->dest_addr = dma_dst;
>> - if (chan->ext_addr) {
>> - hw->src_addr_msb = upper_32_bits(dma_src);
>> - hw->dest_addr_msb = upper_32_bits(dma_dst);
>> - }
>> -
>> - if (prev) {
>> - prev->hw.next_desc = segment->phys;
>> - if (chan->ext_addr)
>> - prev->hw.next_desc_msb =
>> - upper_32_bits(segment->phys);
>> - }
>> -
>> - prev = segment;
>> - dst_avail -= len;
>> - src_avail -= len;
>> - list_add_tail(&segment->node, &desc->segments);
>> -
>> -fetch:
>> - /* Fetch the next dst scatterlist entry */
>> - if (dst_avail == 0) {
>> - if (dst_sg_len == 0)
>> - break;
>> - dst_sg = sg_next(dst_sg);
>> - if (dst_sg == NULL)
>> - break;
>> - dst_sg_len--;
>> - dst_avail = sg_dma_len(dst_sg);
>> - }
>> - /* Fetch the next src scatterlist entry */
>> - if (src_avail == 0) {
>> - if (src_sg_len == 0)
>> - break;
>> - src_sg = sg_next(src_sg);
>> - if (src_sg == NULL)
>> - break;
>> - src_sg_len--;
>> - src_avail = sg_dma_len(src_sg);
>> - }
>> - }
>> -
>> - if (list_empty(&desc->segments)) {
>> - dev_err(chan->xdev->dev,
>> - "%s: Zero-size SG transfer requested\n", __func__);
>> - goto error;
>> - }
>> -
>> - /* Link the last hardware descriptor with the first. */
>> - segment = list_first_entry(&desc->segments,
>> - struct xilinx_cdma_tx_segment, node);
>> - desc->async_tx.phys = segment->phys;
>> - prev->hw.next_desc = segment->phys;
>> -
>> - return &desc->async_tx;
>> -
>> -error:
>> - xilinx_dma_free_tx_descriptor(chan, desc);
>> - return NULL;
>> -}
>> -
>> /**
>> * xilinx_dma_prep_slave_sg - prepare descriptors for a DMA_SLAVE transaction
>> * @dchan: DMA channel
>> @@ -3240,9 +3120,7 @@ static int xilinx_dma_probe(struct platform_device *pdev)
>> DMA_RESIDUE_GRANULARITY_SEGMENT;
>> } else if (xdev->dma_config->dmatype == XDMA_TYPE_CDMA) {
>> dma_cap_set(DMA_MEMCPY, xdev->common.cap_mask);
>> - dma_cap_set(DMA_MEMCPY_SG, xdev->common.cap_mask);
>> xdev->common.device_prep_dma_memcpy = xilinx_cdma_prep_memcpy;
>> - xdev->common.device_prep_dma_memcpy_sg = xilinx_cdma_prep_memcpy_sg;
>> /* Residue calculation is supported by only AXI DMA and CDMA */
>> xdev->common.residue_granularity =
>> DMA_RESIDUE_GRANULARITY_SEGMENT;
>> diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
>> index b46b88e6aa0d1..c923f4e60f240 100644
>> --- a/include/linux/dmaengine.h
>> +++ b/include/linux/dmaengine.h
>> @@ -50,7 +50,6 @@ enum dma_status {
>> */
>> enum dma_transaction_type {
>> DMA_MEMCPY,
>> - DMA_MEMCPY_SG,
>> DMA_XOR,
>> DMA_PQ,
>> DMA_XOR_VAL,
>> @@ -887,11 +886,6 @@ struct dma_device {
>> struct dma_async_tx_descriptor *(*device_prep_dma_memcpy)(
>> struct dma_chan *chan, dma_addr_t dst, dma_addr_t src,
>> size_t len, unsigned long flags);
>> - struct dma_async_tx_descriptor *(*device_prep_dma_memcpy_sg)(
>> - struct dma_chan *chan,
>> - struct scatterlist *dst_sg, unsigned int dst_nents,
>> - struct scatterlist *src_sg, unsigned int src_nents,
>> - unsigned long flags);
>> struct dma_async_tx_descriptor *(*device_prep_dma_xor)(
>> struct dma_chan *chan, dma_addr_t dst, dma_addr_t *src,
>> unsigned int src_cnt, size_t len, unsigned long flags);
>> @@ -1060,20 +1054,6 @@ static inline struct dma_async_tx_descriptor *dmaengine_prep_dma_memcpy(
>> len, flags);
>> }
>>
>> -static inline struct dma_async_tx_descriptor *dmaengine_prep_dma_memcpy_sg(
>> - struct dma_chan *chan,
>> - struct scatterlist *dst_sg, unsigned int dst_nents,
>> - struct scatterlist *src_sg, unsigned int src_nents,
>> - unsigned long flags)
>> -{
>> - if (!chan || !chan->device || !chan->device->device_prep_dma_memcpy_sg)
>> - return NULL;
>> -
>> - return chan->device->device_prep_dma_memcpy_sg(chan, dst_sg, dst_nents,
>> - src_sg, src_nents,
>> - flags);
>> -}
>> -
>> static inline bool dmaengine_is_metadata_mode_supported(struct dma_chan *chan,
>> enum dma_desc_metadata_mode mode)
>> {
>> --
>> 2.30.2
>
>--
>~Vinod
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