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Subject: media: stm32: dcmi: create a dma scatterlist based on DMA max_sg_burst value Author: Alain Volmat <[email protected]> Date: Mon Jan 10 11:37:39 2022 +0100 Prior to submitting a transfer to the DMA, the client should first check the capabilities of the DMA channel in term of maximum of each segment. This is given by the max_sg_burst value reported by dma_get_slave_caps API. Based on that, if the transfer is larger than what can be handled by the DMA channel, we split the transfer into several scatterlist elements. [hverkuil: fix checkpatch parenthesis alignment warning] Signed-off-by: Alain Volmat <[email protected]> Signed-off-by: Hans Verkuil <[email protected]> Signed-off-by: Mauro Carvalho Chehab <[email protected]> drivers/media/platform/stm32/stm32-dcmi.c | 51 +++++++++++++++++++++++-------- 1 file changed, 39 insertions(+), 12 deletions(-) --- diff --git a/drivers/media/platform/stm32/stm32-dcmi.c b/drivers/media/platform/stm32/stm32-dcmi.c index e1b17c05229c..bf76b420352d 100644 --- a/drivers/media/platform/stm32/stm32-dcmi.c +++ b/drivers/media/platform/stm32/stm32-dcmi.c @@ -113,7 +113,7 @@ struct dcmi_framesize { struct dcmi_buf { struct vb2_v4l2_buffer vb; bool prepared; - dma_addr_t paddr; + struct sg_table sgt; size_t size; struct list_head list; }; @@ -157,6 +157,7 @@ struct stm32_dcmi { enum state state; struct dma_chan *dma_chan; dma_cookie_t dma_cookie; + u32 dma_max_burst; u32 misr; int errors_count; int overrun_count; @@ -326,13 +327,11 @@ static int dcmi_start_dma(struct stm32_dcmi *dcmi, mutex_lock(&dcmi->dma_lock); /* Prepare a DMA transaction */ - desc = dmaengine_prep_slave_single(dcmi->dma_chan, buf->paddr, - buf->size, - DMA_DEV_TO_MEM, - DMA_PREP_INTERRUPT); + desc = dmaengine_prep_slave_sg(dcmi->dma_chan, buf->sgt.sgl, buf->sgt.nents, + DMA_DEV_TO_MEM, + DMA_PREP_INTERRUPT); if (!desc) { - dev_err(dcmi->dev, "%s: DMA dmaengine_prep_slave_single failed for buffer phy=%pad size=%zu\n", - __func__, &buf->paddr, buf->size); + dev_err(dcmi->dev, "%s: DMA dmaengine_prep_slave_sg failed\n", __func__); mutex_unlock(&dcmi->dma_lock); return -EINVAL; } @@ -524,6 +523,10 @@ static int dcmi_buf_prepare(struct vb2_buffer *vb) struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb); struct dcmi_buf *buf = container_of(vbuf, struct dcmi_buf, vb); unsigned long size; + unsigned int num_sgs = 1; + dma_addr_t dma_buf; + struct scatterlist *sg; + int i, ret; size = dcmi->fmt.fmt.pix.sizeimage; @@ -537,15 +540,33 @@ static int dcmi_buf_prepare(struct vb2_buffer *vb) if (!buf->prepared) { /* Get memory addresses */ - buf->paddr = - vb2_dma_contig_plane_dma_addr(&buf->vb.vb2_buf, 0); buf->size = vb2_plane_size(&buf->vb.vb2_buf, 0); - buf->prepared = true; + if (buf->size > dcmi->dma_max_burst) + num_sgs = DIV_ROUND_UP(buf->size, dcmi->dma_max_burst); - vb2_set_plane_payload(&buf->vb.vb2_buf, 0, buf->size); + ret = sg_alloc_table(&buf->sgt, num_sgs, GFP_ATOMIC); + if (ret) { + dev_err(dcmi->dev, "sg table alloc failed\n"); + return ret; + } + + dma_buf = vb2_dma_contig_plane_dma_addr(&buf->vb.vb2_buf, 0); dev_dbg(dcmi->dev, "buffer[%d] phy=%pad size=%zu\n", - vb->index, &buf->paddr, buf->size); + vb->index, &dma_buf, buf->size); + + for_each_sg(buf->sgt.sgl, sg, num_sgs, i) { + size_t bytes = min_t(size_t, size, dcmi->dma_max_burst); + + sg_dma_address(sg) = dma_buf; + sg_dma_len(sg) = bytes; + dma_buf += bytes; + size -= bytes; + } + + buf->prepared = true; + + vb2_set_plane_payload(&buf->vb.vb2_buf, 0, buf->size); } return 0; @@ -1866,6 +1887,7 @@ static int dcmi_probe(struct platform_device *pdev) struct stm32_dcmi *dcmi; struct vb2_queue *q; struct dma_chan *chan; + struct dma_slave_caps caps; struct clk *mclk; int irq; int ret = 0; @@ -1953,6 +1975,11 @@ static int dcmi_probe(struct platform_device *pdev) return ret; } + dcmi->dma_max_burst = UINT_MAX; + ret = dma_get_slave_caps(chan, &caps); + if (!ret && caps.max_sg_burst) + dcmi->dma_max_burst = caps.max_sg_burst * DMA_SLAVE_BUSWIDTH_4_BYTES; + spin_lock_init(&dcmi->irqlock); mutex_init(&dcmi->lock); mutex_init(&dcmi->dma_lock); _______________________________________________ linuxtv-commits mailing list [email protected] https://www.linuxtv.org/cgi-bin/mailman/listinfo/linuxtv-commits
