The Linux-3.0.35 distributrion supported sdma mem to mem transfers using the dmaengine api. The imx-sdma driver supported this using two scater gather lists. The imx-sdma would use the ap_2_ap script. This support is no longer in the Linux-3.10.9 distribution.
1. Is this supported in the Linux-3.10.9 or latter distributions?
2. If yes, how has the interface changed from Linux-3.0.35?
3. If no, was there a reason for this feature removal?
Here is a quote from the 3.0.35 imx-sdma driver.
* For SDMA M2M use, we need 2 scatterlists, the src addresses are
* stored in the first sg, and the dst addresses are stored in the
* second sg. In the former code, when the first sg entered 'sdma_
* prep_slave_sg', 'sdmac->status' would be set to 'DMA_IN_PROGRESS',
* and the second sg would return 'NULL' when entered 'sdma_prep_slave
* _sg'. To avoid this error, in the code, we check if for M2M use,
* the second sg will not return 'NULL' when enters 'sdma_prep_slave
Thanks to anyone for input on this issue!!