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

[Sinan Kaya]

> > /*
> > * 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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