linux-kernel - RE: [PATCH] dma-mapping: move dma configuration to bus infrastructure

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Message-ID: <HE1PR0401MB24250A8631823FB3108EA62CE6D20@HE1PR0401MB2425.eurprd04.prod.outlook.com>
Date:   Tue, 13 Mar 2018 04:22:53 +0000
From:   Nipun Gupta <nipun.gupta@....com>
To:     Sinan Kaya <okaya@...eaurora.org>, "hch@....de" <hch@....de>,
        "robin.murphy@....com" <robin.murphy@....com>,
        "linux@...linux.org.uk" <linux@...linux.org.uk>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "m.szyprowski@...sung.com" <m.szyprowski@...sung.com>,
        "bhelgaas@...gle.com" <bhelgaas@...gle.com>
CC:     "dmitry.torokhov@...il.com" <dmitry.torokhov@...il.com>,
        "rafael.j.wysocki@...el.com" <rafael.j.wysocki@...el.com>,
        "jarkko.sakkinen@...ux.intel.com" <jarkko.sakkinen@...ux.intel.com>,
        "linus.walleij@...aro.org" <linus.walleij@...aro.org>,
        "johan@...nel.org" <johan@...nel.org>,
        "msuchanek@...e.de" <msuchanek@...e.de>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        Bharat Bhushan <bharat.bhushan@....com>,
        Leo Li <leoyang.li@....com>
Subject: RE: [PATCH] dma-mapping: move dma configuration to bus infrastructure



> -----Original Message-----
> From: Sinan Kaya [mailto:okaya@...eaurora.org]
> Sent: Monday, March 12, 2018 22:14
> To: Nipun Gupta <nipun.gupta@....com>; hch@....de;
> robin.murphy@....com; linux@...linux.org.uk; gregkh@...uxfoundation.org;
> m.szyprowski@...sung.com; bhelgaas@...gle.com
> Cc: dmitry.torokhov@...il.com; rafael.j.wysocki@...el.com;
> jarkko.sakkinen@...ux.intel.com; linus.walleij@...aro.org; johan@...nel.org;
> msuchanek@...e.de; linux-kernel@...r.kernel.org; iommu@...ts.linux-
> foundation.org; linux-pci@...r.kernel.org
> Subject: Re: [PATCH] dma-mapping: move dma configuration to bus
> infrastructure
> 
> On 3/12/2018 11:24 AM, Nipun Gupta wrote:
> > +	if (dma_dev->of_node) {
> > +		ret = of_dma_configure(dev, dma_dev->of_node);
> > +	} else if (has_acpi_companion(dma_dev)) {
> > +		attr = acpi_get_dma_attr(to_acpi_device_node(dma_dev-
> >fwnode));
> > +		if (attr != DEV_DMA_NOT_SUPPORTED)
> > +			ret = acpi_dma_configure(dev, attr);
> > +	}
> > +
> > +	pci_put_host_bridge_device(bridge);
> > +
> > +	return ret;
> > +}
> > +
> > +void pci_dma_deconfigure(struct device *dev)
> > +{
> > +	of_dma_deconfigure(dev);
> > +	acpi_dma_deconfigure(dev);
> > +}
> 
> Isn't this one or the other one but not both?
> 
> Something like:
> 
> if (dev->of_node)
> 	of_dma_deconfigure(dev);
> else
> 	acpi_dma_deconfigure(dev);
> 
> should work.

I understand your point. Seems reasonable as we should not expect
the 'of/acpi DMA deconfigure' API to not fail when they are not configured.

But, here we would also need to get dma_device (just as we get in
'pci_dma_configure') and need a check on it as for PCI there 'of_node'
is present in the dma_dev.

Ill update this in v2, and also make similar changes for platform and AMBA bus.

Thanks,
Nipun

> 
> --
> Sinan Kaya
> Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm
> Technologies, Inc.
> Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux
> Foundation Collaborative Project.