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media: stm32: dcmi: create a dma scatterlist based on DMA max_sg_burst value 

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 <alain.volmat@foss.st.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
This commit is contained in:
Alain Volmat 2022-01-10 11:37:39 +01:00 committed by Mauro Carvalho Chehab
parent fc5004e5d4
commit c1b403352c
1 changed files with 39 additions and 12 deletions
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51
drivers/media/platform/stm32/stm32-dcmi.c
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@ -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);
if (buf->size > dcmi->dma_max_burst)
num_sgs = DIV_ROUND_UP(buf->size, dcmi->dma_max_burst);
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, &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);
dev_dbg(dcmi->dev, "buffer[%d] phy=%pad size=%zu\n",
vb->index, &buf->paddr, 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);