linux-kernel - Re: [PATCH 1/5] PCI: endpoint: functions/pci-epf-test: Add DMA support to transfer data

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Date:   Tue, 3 Mar 2020 15:57:13 -0800
From:   Alan Mikhak <alan.mikhak@...ive.com>
To:     Kishon Vijay Abraham I <kishon@...com>
Cc:     amurray@...goodpenguin.co.uk, arnd@...db.de,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
        linux-pci <linux-pci@...r.kernel.org>, lorenzo.pieralisi@....com
Subject: Re: [PATCH 1/5] PCI: endpoint: functions/pci-epf-test: Add DMA
 support to transfer data

On Wed, Feb 26, 2020 at 9:39 AM Alan Mikhak <alan.mikhak@...ive.com> wrote:
>
> On Tue, Feb 25, 2020 at 9:27 PM Kishon Vijay Abraham I <kishon@...com> wrote:
> >
> > Hi Alan,
> >
> > On 26/02/20 2:41 am, Alan Mikhak wrote:
> > > @@ -380,6 +572,7 @@ static void pci_epf_test_unbind(struct pci_epf *epf)
> > >         int bar;
> > >
> > >         cancel_delayed_work(&epf_test->cmd_handler);
> > > +       pci_epf_clean_dma_chan(epf_test);
> > >         pci_epc_stop(epc);
> > >         for (bar = 0; bar < PCI_STD_NUM_BARS; bar++) {
> > >                 epf_bar = &epf->bar[bar];
> > > @@ -550,6 +743,12 @@ static int pci_epf_test_bind(struct pci_epf *epf)
> > >                 }
> > >         }
> > >
> > > +       epf_test->dma_supported = true;
> > > +
> > > +       ret = pci_epf_init_dma_chan(epf_test);
> > > +       if (ret)
> > > +               epf_test->dma_supported = false;
> > > +
> > >         if (linkup_notifier) {
> > >                 epf->nb.notifier_call = pci_epf_test_notifier;
> > >                 pci_epc_register_notifier(epc, &epf->nb);
> > >
> > > Hi Kishon,
> > >
> > > Looking forward to building and trying this patch series on
> > > a platform I work on.

Hi Kishon,

I applied this v1 patch series to kernel.org linux 5.6-rc3 and built for
x86_64 Debian and riscv. I verified that when I execute the pcitest
command on the x86_64 host with -d flag, the riscv endpoint performs
the transfer by using an available dma channel.

Regards,
Alan

> > >
> > > Would you please point me to where I can find the patches
> > > which add pci_epf_init_dma_chan() and pci_epf_clean_dma_chan()
> > > to Linux PCI Endpoint Framework?
> >
> > I've added these functions in pci-epf-test itself instead of adding in
> > the core files. I realized adding it in core files may not be helpful if
> > the endpoint function decides to use more number of DMA channels etc.,
>
> Thanks Kishon,
>
> I now realize they are in [PATCH 1/5] of this series. May I suggest renaming
> them to pci_epf_test_init_dma_chan() and pci_epf_test_cleanup_dma_chan()?
> With just pci_epf in their name, I was looking for them in pci-epf-core.c.
>
> Regards,
> Alan
>
> >
> > Thanks
> > Kishon