On 28.09.2017 17:06, Dmitry Osipenko wrote: > On 28.09.2017 12:29, Vinod Koul wrote: >>> + default: >>> + return -EINVAL; >>> + } >>> + >>> + ahb_seq = burst << TEGRA_AHBDMA_CHANNEL_AHB_BURST_SHIFT; >>> + ahb_seq |= TEGRA_AHBDMA_CHANNEL_ADDR_WRAP; >>> + ahb_seq |= TEGRA_AHBDMA_CHANNEL_INTR_ENB; >>> + >>> + writel_relaxed(ahb_seq, >>> + ahbdma_chan->regs + TEGRA_AHBDMA_CHANNEL_AHB_SEQ); >>> + >>> + writel_relaxed(ahb_addr, >>> + ahbdma_chan->regs + TEGRA_AHBDMA_CHANNEL_AHB_PTR); >> >> oh no, you don't write to HW here. This can be called anytime when you have >> txn running! You should save these and use them in prep_ calls. >> > > BTW, some of the DMA drivers have exactly the same problem. I now see that it > is > actually documented explicitly in provider.txt, but that's inconsistent across > the actual drivers. >
Also, shouldn't prep_ and dma_slave_config be protected with locking? I don't see DMA core doing any locking and seems none of the drivers too. -- Dmitry
