LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Catalin Marinas <catalin.marinas@arm.com>
To: Robin Murphy <Robin.Murphy@arm.com>
Cc: Murali Karicheri <m-karicheri2@ti.com>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	Russell King <linux@arm.linux.org.uk>,
	Arnd Bergmann <arnd@arndb.de>,
	"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
	Joerg Roedel <joro@8bytes.org>, Will Deacon <Will.Deacon@arm.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"grant.likely@linaro.org" <grant.likely@linaro.org>,
	"iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>,
	Rob Herring <robh+dt@kernel.org>,
	"suravee.suthikulpanit@amd.com" <suravee.suthikulpanit@amd.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v4 3/6] of: fix size when dma-range is not used
Date: Wed, 28 Jan 2015 17:30:48 +0000	[thread overview]
Message-ID: <20150128173048.GE31752@e104818-lin.cambridge.arm.com> (raw)
In-Reply-To: <54C9068D.8050701@arm.com>

On Wed, Jan 28, 2015 at 03:55:57PM +0000, Robin Murphy wrote:
> On 28/01/15 11:05, Catalin Marinas wrote:
> > On Tue, Jan 27, 2015 at 06:55:15PM +0000, Murali Karicheri wrote:
> >> How about having the logic like this?
> >>
> >> 	ret = of_dma_get_range(np, &dma_addr, &paddr, &size);
> >> 	if (ret < 0) {
> >> 		dma_addr = offset = 0;
> >> 		size = dev->coherent_dma_mask + 1;
> >> 	} else {
> >> 		offset = PFN_DOWN(paddr - dma_addr);
> >> 		dev_dbg(dev, "dma_pfn_offset(%#08lx)\n", offset);
> >> 	}
> >>
> >> 	if (is_power_of_2(size + 1))
> >> 		size = size + 1;
> >> 	else if (!is_power_of_2(size))
> >> 	{
> >> 		dev_err(dev, "invalid size\n");
> >> 		return;
> >> 	}
> >
> > In of_dma_configure(), we currently assume that the default coherent
> > mask is 32-bit. In this thread:
> >
> > http://article.gmane.org/gmane.linux.kernel/1835096
> >
> > we talked about setting the coherent mask based on size automatically.
> > I'm not sure about the size but I think we can assume is 32-bit mask + 1
> > if it is not specified in the DT. Instead of just assuming a default
> > mask, let's assume a default size and create the mask based on this
> > (untested):
> >
> > diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> > index 5b33c6a21807..9ff8d1286b44 100644
> > --- a/drivers/of/platform.c
> > +++ b/drivers/of/platform.c
> > @@ -170,10 +170,10 @@ static void of_dma_configure(struct device *dev)
> >   	struct iommu_ops *iommu;
> >
> >   	/*
> > -	 * Set default dma-mask to 32 bit. Drivers are expected to setup
> > -	 * the correct supported dma_mask.
> > +	 * Set default size to cover the 32-bit. Drivers are expected to setup
> > +	 * the correct size and dma_mask.
> >   	 */
> > -	dev->coherent_dma_mask = DMA_BIT_MASK(32);
> > +	size = 1ULL << 32;
> >
> >   	/*
> >   	 * Set it to coherent_dma_mask by default if the architecture
> > @@ -185,13 +185,24 @@ static void of_dma_configure(struct device *dev)
> >   	ret = of_dma_get_range(dev->of_node, &dma_addr, &paddr, &size);
> >   	if (ret < 0) {
> >   		dma_addr = offset = 0;
> > -		size = dev->coherent_dma_mask;
> >   	} else {
> >   		offset = PFN_DOWN(paddr - dma_addr);
> >   		dev_dbg(dev, "dma_pfn_offset(%#08lx)\n", dev->dma_pfn_offset);
> >   	}
> >   	dev->dma_pfn_offset = offset;
> >
> > +	/*
> > +	 * Workaround for DTs setting the size to a mask or 0.
> > +	 */
> > +	if (is_power_of_2(size + 1))
> > +		size += 1;
> 
> In fact, since the ilog2 below ends up effectively rounding down, we 
> might as well do away with this check as well and just add 1 
> unconditionally. The only time it makes any difference is when we want 
> it to anyway!

Well, we could simply ignore the is_power_of_2() check but without
incrementing size as we don't know what arch_setup_dma_ops() does with
it.

I think we can remove this check altogether (we leaved without it for a
while) but we need to add 1 when calculating the mask:

	dev->coherent_dma_mask = min(DMA_BIT_MASK(32),
				     DMA_BIT_MASK(ilog2(size + 1)));

-- 
Catalin

  reply	other threads:[~2015-01-29  2:28 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-23 22:32 [PATCH v4 0/6] PCI: get DMA configuration from parent device Murali Karicheri
2015-01-23 22:32 ` [PATCH v4 1/6] of: iommu: add ptr to OF node arg to of_iommu_configure() Murali Karicheri
2015-01-25 13:32   ` Laurent Pinchart
2015-01-26 18:49     ` Murali Karicheri
2015-01-28 11:33       ` Will Deacon
2015-01-28 12:23         ` Laurent Pinchart
2015-01-28 12:29           ` Will Deacon
2015-01-28 13:15             ` Laurent Pinchart
2015-01-28 13:32               ` Will Deacon
2015-01-28 15:21                 ` Murali Karicheri
2015-01-28 23:32                 ` Laurent Pinchart
2015-01-29 14:59                   ` Murali Karicheri
2015-01-29 16:49                   ` Rob Herring
2015-01-30  0:24                     ` Laurent Pinchart
2015-01-30 15:23                       ` Murali Karicheri
2015-01-23 22:32 ` [PATCH v4 2/6] of: move of_dma_configure() to device.c to help re-use Murali Karicheri
2015-01-23 22:32 ` [PATCH v4 3/6] of: fix size when dma-range is not used Murali Karicheri
2015-01-27 11:27   ` Robin Murphy
2015-01-27 15:44     ` Murali Karicheri
2015-01-27 18:55     ` Murali Karicheri
2015-01-28 11:05       ` Catalin Marinas
2015-01-28 15:45         ` Rob Herring
2015-01-28 17:23           ` Catalin Marinas
2015-01-28 17:34           ` Murali Karicheri
2015-01-28 15:55         ` Robin Murphy
2015-01-28 17:30           ` Catalin Marinas [this message]
2015-01-30 18:06             ` Murali Karicheri
2015-02-02 12:18               ` Catalin Marinas
2015-02-02 16:10                 ` Murali Karicheri
2015-02-05 21:42                 ` Murali Karicheri
2015-02-05 22:44                   ` Catalin Marinas
2015-01-23 22:32 ` [PATCH v4 4/6] of/pci: add of_pci_dma_configure() update dma configuration Murali Karicheri
2015-01-23 23:41   ` Bjorn Helgaas
2015-01-26 23:25     ` Murali Karicheri
2015-01-26 23:59       ` Bjorn Helgaas
2015-01-27 18:14         ` Murali Karicheri
2015-01-27 18:42           ` Bjorn Helgaas
2015-01-27 18:45             ` Murali Karicheri
2015-01-23 22:32 ` [PATCH v4 5/6] PCI: update dma configuration from DT Murali Karicheri
2015-01-23 23:27   ` Bjorn Helgaas
2015-01-26 23:28     ` Murali Karicheri
2015-01-23 22:32 ` [PATCH v4 6/6] arm: dma-mapping: updates to limit dma_mask and iommu mapping size Murali Karicheri
2015-01-27 11:12   ` Robin Murphy
2015-01-27 11:34     ` Catalin Marinas
2015-01-27 15:19       ` Murali Karicheri

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20150128173048.GE31752@e104818-lin.cambridge.arm.com \
    --to=catalin.marinas@arm.com \
    --cc=Robin.Murphy@arm.com \
    --cc=Will.Deacon@arm.com \
    --cc=arnd@arndb.de \
    --cc=bhelgaas@google.com \
    --cc=devicetree@vger.kernel.org \
    --cc=grant.likely@linaro.org \
    --cc=iommu@lists.linux-foundation.org \
    --cc=joro@8bytes.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pci@vger.kernel.org \
    --cc=linux@arm.linux.org.uk \
    --cc=m-karicheri2@ti.com \
    --cc=robh+dt@kernel.org \
    --cc=suravee.suthikulpanit@amd.com \
    --subject='Re: [PATCH v4 3/6] of: fix size when dma-range is not used' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).