Tool/software: Linux
CPU：AM335x
Linux Kernel：4.4.10
I'm working on am335x's dma, my goal is to use a gpio interrupt to trigger a EDMA's mem to mem transfer, that copying 8 bytes from GPMC SRAM to ram.
The trigger gpio is GP2[29], which is a indirect mapped dma event.
I add the dma binding code in dts file:
dma_test {
compatible = "cet,am335x-dma-test";
status = "okay";
dmas = <&edma_xbar 32 0 32>;
dma-names = "dma_test";
};
My test code is listed below, I have tried two methods to request a dma channel, but have different result.
dma_cap_zero(mask);
dma_cap_set(DMA_MEMCPY, mask);
/* !!!!!!!!!!!!!!!!!!!!!! */
/* Method 1: dma_request_channel without any param */
dma_ch = dma_request_channel(mask, 0, NULL);
/* Methed 2: dma_request_chan, which can obtain dma channel info. specified in dts file */
dma_ch = dma_request_chan(&pdev->dev, "dma_test");/* no place to pass mask */
if (dma_ch == NULL)
{
printk("request_channel failed.\n");
goto err;
}
printk("got dma_ch = 0x%x\n", dma_ch);
rxconf.src_addr = ADC_ADDR;
rxconf.dst_addr = dma_buf_phys_addr;
rxconf.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
rxconf.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
rxconf.src_maxburst = 1;
rxconf.dst_maxburst = 1;
rxconf.device_fc = 0;
rxconf.slave_id = 0;
ret = dmaengine_slave_config(dma_ch, &rxconf);
if (ret)
goto err;
printk("dmaengine_slave_config pass.\n");
/* debug: print device struct info */
dma_ch_debug(dma_ch);
if (dma_ch->device->device_prep_dma_memcpy == NULL)
{
printk("device_prep_dma_memcpy = NULL\n");
goto err;
}
tx_desc = dma_ch->device->device_prep_dma_memcpy(dma_ch, dma_buf_phys_addr, ADC_ADDR,
8, DMA_CTRL_ACK | DMA_PREP_INTERRUPT);
if (!tx_desc)
goto err;
printk("device_prep_dma_memcpy pass.\n");
tx_desc->callback = dma_callback_func;
tx_desc->callback_param = NULL;
cookie = tx_desc->tx_submit(tx_desc); //submit the desc
if (dma_submit_error(cookie)){
printk(KERN_INFO "Failed to do DMA tx_submit");
goto err;
}
printk("tx_submit pass.\n");
dma_async_issue_pending(dma_ch);
When I use dma_request_channel() API, I get a memcpy only dma channel:
[ 1349.049411] Key get value 1 [ 1349.060336] read 8 bytes: [ 1349.063125] 00 05 c1 13 0b 60 f0 5b [ 1349.074218] got dma_buf = 0xf0ea8000 dma_buf_phys_addr = 0xbd042000 [ 1349.085953] got dma_ch = 0xee9715f0 [ 1349.092285] dmaengine_slave_config pass. [ 1349.096434] device = 0xee93dcd0 [ 1349.104284] device->chancnt = 2 [ 1349.110178] device->dev_id = 1 [ 1349.113406] device->dev = 0xee90fa10 [ 1349.121617] device->filter = 0x00000000 [ 1349.125670] device->cap_mask = 0x601 // !! [ 1349.133862] device->device_config = 0xc02598c4 [ 1349.141089] device->device_prep_dma_memcpy=0xc0259938 // !! [ 1349.146424] device->device_prep_slave_sg = 0x00000000 // !! [ 1349.156189] device->device_prep_slave_cyclic = 0x00000000 // !! [ 1349.164455] tx_submit pass. [ 1349.170017] 00 05 c1 13 0b 60 f0 5b
It can start a mem_to_mem transfer but without GPIO trigger.
The cap_mask is only DMA_MEMCPY, DMA_ASYNC_TX..
When I use dma_request_chanl() API, I get a hw triggered dma channel but it does not have device_prep_dma_memcpy() function registed.
The cap_mask is 0x1E00, which DMA_MEMCPY bit is not set.
[ 1373.798536] Key get value 1 [ 1373.810160] read 8 bytes: [ 1373.812952] 00 05 c1 13 0b 60 f0 5b [ 1373.824948] got dma_buf = 0xf0eca000 dma_buf_phys_addr = 0xbd042000 [ 1373.834724] got dma_ch = 0xee972310 [ 1373.841227] dmaengine_slave_config pass. [ 1373.845376] device = 0xee94f044 [ 1373.853261] device->chancnt = 62 [ 1373.859267] device->dev_id = 0 [ 1373.862495] device->dev = 0xee90fa10 [ 1373.866261] device->filter = 0xc025a2bc [ 1373.876557] device->cap_mask = 0x1e00 // !! [ 1373.883061] device->device_config = 0xc02598c4 [ 1373.890323] device->device_prep_dma_memcpy=0x00000000 // !! [ 1373.895657] device->device_prep_slave_sg = 0xc0259f8c // !! [ 1373.905423] device->device_prep_slave_cyclic = 0xc0259b90 // !! [ 1373.913609] device_prep_dma_memcpy = NULL
Question:
How can I get a event binded DMA_MEMCPY channel using dmaengine API?
