Hi Daniel, On Monday 07 April 2014 15:25:19 Daniel Mack wrote: > Hi Laurent, > > (copying some more people) > > On 04/07/2014 03:12 PM, Laurent Pinchart wrote: > > The MMP DMA (drivers/dma/mmap_pdma.c) driver supports the DMA engine found > > in PXA chips. However, PXA platforms still use a mix of custom platform > > code (arch/arm/plat-pxa/dma.c) and direct DMA controller access in > > various drivers (pata_pxa, spi-pxa2xx, pxa3xx_nand, pxaficp_ir, pxamci, > > smc91x, smc911x and pxa_camera). > > > > I'd like to use the MMP PDMA driver through the DMA engine API in a new > > driver I'm writing instead of the legacy PXA DMA code. However, this > > requires porting the platform to the MMP PDMA driver first, which > > involves porting all the above drivers to the DMA engine API. The > > spi-pxa2xx driver has already been ported and currently supports both the > > legacy PXA DMA API and the DMA engine API. All the other drivers seem to > > require the legacy PXA DMA API. > > > > I was wondering if any effort had been started in that direction. I could > > possibly help with the pxamci driver, but not with the other drivers as > > the corresponding peripherals are not used on my test platform (a custom > > PXA27x board). > > Yes, I've started working on this a long time ago, but got stuck because > of the lack of support from users, as I don't have hardware with all > possible DMA-capable components in use. Have a look here, the tree > should be easily rebasable onto newer versions: > > https://github.com/zonque/linux/tree/pxa-dma-v3 Thank you, that's helpful. > * I ported some drivers blindly, and Marek Vasut reported success on the > pxa-pata driver. > > * The spi-driver just works thanks to previous preparations. > > * The mmc driver seems to work, but people reported significant > performance loss in comparison to the current code. I'll try to test it. > * I ported over the ASoC drivers so the dma framework can be used as > drop-in replacement. One patch for mmp-pdma residue reporting is pending > though, I need to get back to Vinod on that. > > * One thing that was especially tricky to port was the camera driver, > and Robert wasn't sure whether the type of DMA hot-linking which his > driver does was at all doable with the DMA framework as it stands. > > > Which PXA based hardware can you get your hands on for testing? It would > be good to get some movement into this topic again :) I only have access to a custom pxa27x board. I'm working on a driver for an FPGA-based device that requires DMA in fly-by mode, so I'll need to implement support for that in the mmp_pdma driver. -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
