On Thu, Sep 28, 2017 at 05:35:59PM +0300, Dmitry Osipenko wrote: > 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. In prep when you modify the list yes (with vchan I suspect that maybe taken care), but in general yes driver needs to do that -- ~Vinod -- 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
