06.08.2020 10:30, Rajesh Gumasta пишет:
...
> +/*
> + * Save and restore csr and channel register on pm_suspend
> + * and pm_resume respectively
> + */
> +static int __maybe_unused tegra_dma_pm_suspend(struct device *dev)
> +{
> + struct tegra_dma *tdma = dev_get_drvdata(dev);
> + int i;
> +
> + for (i = 0; i < tdma->chip_data->nr_channels; i++) {
> + struct tegra_dma_channel *tdc = &tdma->channels[i];
> + struct tegra_dma_channel_regs *ch_reg = &tdc->channel_reg;
> +
> + ch_reg->csr = tdc_read(tdc, TEGRA_GPCDMA_CHAN_CSR);
> + ch_reg->src_ptr = tdc_read(tdc, TEGRA_GPCDMA_CHAN_SRC_PTR);
> + ch_reg->dst_ptr = tdc_read(tdc, TEGRA_GPCDMA_CHAN_DST_PTR);
> + ch_reg->high_addr_ptr = tdc_read(tdc,
> + TEGRA_GPCDMA_CHAN_HIGH_ADDR_PTR);
> + ch_reg->mc_seq = tdc_read(tdc, TEGRA_GPCDMA_CHAN_MCSEQ);
> + ch_reg->mmio_seq = tdc_read(tdc, TEGRA_GPCDMA_CHAN_MMIOSEQ);
> + ch_reg->wcount = tdc_read(tdc, TEGRA_GPCDMA_CHAN_WCOUNT);
> + }
> + return 0;
> +}
> +
> +static int __maybe_unused tegra_dma_pm_resume(struct device *dev)
> +{
> + struct tegra_dma *tdma = dev_get_drvdata(dev);
> + int i;
> +
> + for (i = 0; i < tdma->chip_data->nr_channels; i++) {
> + struct tegra_dma_channel *tdc = &tdma->channels[i];
> + struct tegra_dma_channel_regs *ch_reg = &tdc->channel_reg;
> +
> + tdc_write(tdc, TEGRA_GPCDMA_CHAN_WCOUNT, ch_reg->wcount);
> + tdc_write(tdc, TEGRA_GPCDMA_CHAN_DST_PTR, ch_reg->dst_ptr);
> + tdc_write(tdc, TEGRA_GPCDMA_CHAN_SRC_PTR, ch_reg->src_ptr);
> + tdc_write(tdc, TEGRA_GPCDMA_CHAN_HIGH_ADDR_PTR,
> + ch_reg->high_addr_ptr);
> + tdc_write(tdc, TEGRA_GPCDMA_CHAN_MMIOSEQ, ch_reg->mmio_seq);
> + tdc_write(tdc, TEGRA_GPCDMA_CHAN_MCSEQ, ch_reg->mc_seq);
> + tdc_write(tdc, TEGRA_GPCDMA_CHAN_CSR,
> + (ch_reg->csr & ~TEGRA_GPCDMA_CSR_ENB));
> + }
> + return 0;
> +}
> +
> +static const struct __maybe_unused dev_pm_ops tegra_dma_dev_pm_ops = {
> + SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(tegra_dma_pm_suspend, tegra_dma_pm_resume)
> +};
Please explain why this is needed. All DMA should be stopped (not
paused) on system's suspend, shouldn't it?
