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 field gets thrown into the SuperH maintainers' basket ;-) At least in 4.14 there were two DMA apis, once of which is obsolete and unused, and the other is modern dmaengine support which at least passes its self-test.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... >> 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...) Rob
