Hi Rob, On Tue, Nov 13, 2018 at 8:32 PM Rob Landley <rob@xxxxxxxxxxx> wrote: > On 11/12/18 9:30 AM, Geert Uytterhoeven wrote: > > CC SuperH > > > > On Mon, Nov 12, 2018 at 4:22 PM Geert Uytterhoeven > > <geert+renesas@xxxxxxxxx> wrote: > >> Renesas R-Mobile APE6 support is currently unused: > >> - DMA slaves were never enabled in r8a73a4.dtsi, > >> - The driver relies on legacy filter matching and describing all > >> slaves and MID/RIDs in a table, unlike modern DMA engine drivers for > >> similar hardware like rcar-dmac, > >> - The driver doesn't seem to work well. > >> > >> Remove the driver, it can be resurrected from git history when needed. > >> > >> As this was the last user of SH_DMAE_BASE on Renesas ARM SoCs, the > >> sh-dma-engine driver core is now used on SuperH only. > > I'm trying to add dma support to smc91x on an sh7760 board: > > https://www.spinics.net/lists/linux-sh/msg53400.html > > I missed the ship window for the previous iteration so we had to use PIO, but > DMA's a huge speedup and it's cycling back around on my todo list... > > Unfortunately due to a flash corruption bug we were stuck at 4.14 for that > release. I'm trying to track that down now, then need to redo this work on top > of 4.20 or 4.21. > > Kernel board support patches are at the lawyers being frowned at expensively > before release, but it won't include DMA this time because I only got the first > half of it working. (Board's hooked up and can do memory-to-memory, but the > ethernet card couldn't use it because the smc91x claims of using dmaengine are > lies, it's hardwired to a specific arm chip ("mainstone" I think?), and when I > got QEMU to emulate that ARM board and tried to enable DMA: packet timeouts. I > dunno if it's broken in the kernel or QEMU doesn't emulate the DMA...) > > >> Notes: > >> 1. As Renesas ARM SoCs no longer use drivers/dma/sh/shdma-base.c, the > >> task to remove use of the deprecated dma_slave_config.direction > >> field gets thrown into the SuperH maintainers' basket ;-) > > At least in 4.14 there were two DMA apis, once of which is obsolete and unused, > and the other is modern dmaengine support which at least passes its self-test. > > I left off boggling at the "slave API", I think... Yes, there's SH_DMA_API and the "new" DMA_ENGINE API. > >> 3. I tried to get SCIFA DMA to work by: > >> - Applying the DT and driver patches below, > >> - Reverting 219fb0c1436e4893 ("serial: sh-sci: Remove the > >> platform data dma slave rx/tx channel IDs"). > > The board I'm using is platform data, never got converted to device tree. (If I > can ever convince them to mail a board to Rich Felker I might try to hire him to > convert it _myself_. Or I could just get him an old board on ebay, current > cheapest one looks like > https://www.ebay.com/p/Johnson-Controls-Ms-nae3511-2-Metasys-Controller-NAE-and-2x-Unt1108/567230953?iid=283254042308 > at the moment? Dead battery's fine for a dev/test system...) > > But it's not happening this month. > > >> After that, serial console output using DMA seems to work, but the > >> system locks up when receiving any serial console input. > >> Probably it is easier to add r8a73a4 support to rcar-dmac. > > What _is_ the status of dmaengine? I thought it was the generic dma API the > kernel was moving towards? (The youtube videos suggested such...) Dmaengine is working on the Renesas R-Car Gen2 and Gen3 SoCs, using rcar-dmac and usb-dmac. But that's ARM (32/64-bit), not SuperH. I'm afraid you're on your own on SuperH... Good luck! Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
