Re: [PATCH V2 2/2] dmaengine: tegra-adma: Add support for Tegra210 ADMA

From: Jon Hunter
Date: Wed Oct 14 2015 - 09:34:33 EST



On 14/10/15 12:27, Vinod Koul wrote:
> On Mon, Oct 05, 2015 at 01:10:07PM +0100, Jon Hunter wrote:
>
>> +static enum dma_status tegra_adma_tx_status(struct dma_chan *dc,
>> + dma_cookie_t cookie,
>> + struct dma_tx_state *txstate)
>> +{
>> + struct tegra_adma_chan *tdc = to_tegra_adma_chan(dc);
>> + struct tegra_adma_desc *desc;
>> + struct virt_dma_desc *vd;
>> + enum dma_status ret;
>> + unsigned long flags;
>> + unsigned int residual;
>> +
>> + spin_lock_irqsave(&tdc->lock, flags);
>> +
>> + ret = dma_cookie_status(dc, cookie, txstate);
>> + if (ret == DMA_COMPLETE) {
>> + spin_unlock_irqrestore(&tdc->lock, flags);
>> + return ret;
>> + }
>
> txstate can be NULL, upon which below code doesn't help in getting executed
> so bailing here or above case is fine

Ok, will fix.

>> +static struct dma_async_tx_descriptor *tegra_adma_prep_dma_cyclic(
>> + struct dma_chan *dc, dma_addr_t buf_addr, size_t buf_len,
>> + size_t period_len, enum dma_transfer_direction direction,
>> + unsigned long flags)
>> +{
>> + struct tegra_adma_chan *tdc = to_tegra_adma_chan(dc);
>> + struct tegra_adma_desc *desc = NULL;
>> +
>> + if (!tdc->config_valid) {
>> + dev_err(tdc2dev(tdc), "ADMA slave configuration not set\n");
>> + return NULL;
>> + }
>> +
>> + if (!buf_len || !period_len || period_len > ADMA_CH_TC_COUNT_MASK) {
>> + dev_err(tdc2dev(tdc), "invalid buffer/period len\n");
>> + return NULL;
>> + }
>> +
>> + if (buf_len % period_len) {
>> + dev_err(tdc2dev(tdc), "buf_len not a multiple of period_len\n");
>> + return NULL;
>> + }
>> +
>> + if (!IS_ALIGNED(buf_addr, 4)) {
>> + dev_err(tdc2dev(tdc), "invalid buffer alignment\n");
>> + return NULL;
>> + }
>> +
>> + desc = kzalloc(sizeof(*desc), GFP_ATOMIC);
>
> we recommend GFP_NOWAIT for the subsystem

Ok, makes sense. I should probably fix up the tegra APB dma driver too.

>> +static int tegra_adma_remove(struct platform_device *pdev)
>> +{
>> + struct tegra_adma *tdma = platform_get_drvdata(pdev);
>> + struct tegra_adma_chan *tdc;
>> + int i;
>> +
>> + dma_async_device_unregister(&tdma->dma_dev);
>> +
>> + for (i = 0; i < tdma->nr_channels; ++i) {
>> + tdc = &tdma->channels[i];
>> + tasklet_kill(&tdc->vc.task);
>> + }
> this is good, but your irq is still active and can fire and thus trigger
> more tasklets!

Ah, yes. Will fix.

Thanks!
Jon

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