Re: [PATCH V2 3/3] dma: add Qualcomm Technologies HIDMA channel driver

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/*
* We are posting descriptors to the hardware as soon as
* they are ready, so this function does nothing.
*/

So, the Freescale driver was written before change went effective. I
guess in 2011 DMA Engine drivers should use issue pending.
Please, refactor since this behaviour is expected.


done

+/*
+ * Submit descriptor to hardware.
+ * Lock the PM for each descriptor we are sending.
+ */
+static dma_cookie_t hidma_tx_submit(struct dma_async_tx_descriptor *txd)
+{
+       struct hidma_chan *mchan = to_hidma_chan(txd->chan);
+       struct hidma_dev *dmadev = mchan->dmadev;
+       struct hidma_desc *mdesc;
+       unsigned long irqflags;
+       dma_cookie_t cookie;
+
+       if (!hidma_ll_isenabled(dmadev->lldev))
+               return -ENODEV;
+
+       pm_runtime_get_sync(dmadev->ddev.dev);


No point to do it here. It should be done on the function that
actually starts the transfer (see issue pending).

comment above

See above as well.

done


+static int hidma_probe(struct platform_device *pdev)
+{
+       struct hidma_dev *dmadev;
+       int rc = 0;
+       struct resource *trca_resource;
+       struct resource *evca_resource;
+       int chirq;
+       int current_channel_index = atomic_read(&channel_ref_count);
+

+       /* Set DMA mask to 64 bits. */
+       rc = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
+       if (rc) {
+               dev_warn(&pdev->dev, "unable to set coherent mask to
64");
+               rc = dma_set_mask_and_coherent(&pdev->dev,
DMA_BIT_MASK(32));
+       }
+       if (rc)
+               goto dmafree;

Maybe move these two lines inside previous condition?

ok


+
+       dmadev->lldev = hidma_ll_init(dmadev->ddev.dev,
+                               dmadev->nr_descriptors, dmadev->dev_trca,
+                               dmadev->dev_evca, dmadev->evridx);
+       if (!dmadev->lldev) {
+               rc = -EPROBE_DEFER;
+               goto dmafree;
+       }
+
+       rc = devm_request_irq(&pdev->dev, chirq, hidma_chirq_handler, 0,
+                             "qcom-hidma", &dmadev->lldev);


Better to use request_irq().


why? I thought we favored managed functions over standalone functions in
simplify the exit path.

IRQ is slightly different in workflow. In most cases, unfortunately,
there is no achievement by devm_ variant.
At least I know two for now. One of them is DMA Engine slave drivers,
though I didn't notice if you are using tasklet's here.
Otherwise it's okay.

I'm keeping it as it is for maintenance reasons.

--
Sinan Kaya
Qualcomm Technologies, Inc. on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project
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