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From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: linux-pci@vger.kernel.org, linux-mediatek@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	"Ryder Lee" <ryder.lee@mediatek.com>,
	"Jianjun Wang" <jianjun.wang@mediatek.com>,
	"Lorenzo Pieralisi" <lpieralisi@kernel.org>,
	"Krzysztof Wilczyński" <kw@linux.com>,
	"Rob Herring" <robh@kernel.org>,
	"Bjorn Helgaas" <bhelgaas@google.com>,
	"Matthias Brugger" <matthias.bgg@gmail.com>,
	"AngeloGioacchino Del Regno"
	<angelogioacchino.delregno@collabora.com>,
	"Huacai Chen" <chenhuacai@kernel.org>,
	"kernel test robot" <lkp@intel.com>
Subject: Re: [PATCH v2 1/1] PCI: mediatek: Correct type for virt_to_phys()
Date: Sat, 16 Sep 2023 13:41:59 +0300	[thread overview]
Message-ID: <ZQWGd/RyKaUBRhUY@smile.fi.intel.com> (raw)
In-Reply-To: <20230914203146.GA77870@bhelgaas>

On Thu, Sep 14, 2023 at 03:31:46PM -0500, Bjorn Helgaas wrote:
> On Thu, Sep 14, 2023 at 10:23:24PM +0300, Andy Shevchenko wrote:

...

> > -	addr = virt_to_phys(port->base + PCIE_MSI_VECTOR);
> > +	addr = virt_to_phys((__force void *)port->base + PCIE_MSI_VECTOR);
> 
> Lots of these drivers use either virt_to_phys() or
> platform_get_resource_byname() to get a physical address that they
> then use as the MSI target.
> 
> But I don't think that's quite right -- the MSI is a DMA transaction
> on PCI, and in general there's no guarantee that bus addresses are
> identical to CPU physical addresses, so shouldn't we use a dma_addr_t
> obtained from the DMA API?
> 
> dw_pcie_msi_host_init() has a complicated version of this that uses
> dmam_alloc_coherent().

Fair enough. I leave it to you then to get it fixed properly.
Consider this as just a heads up for the old report.

-- 
With Best Regards,
Andy Shevchenko




WARNING: multiple messages have this Message-ID (diff)
From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: linux-pci@vger.kernel.org, linux-mediatek@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	"Ryder Lee" <ryder.lee@mediatek.com>,
	"Jianjun Wang" <jianjun.wang@mediatek.com>,
	"Lorenzo Pieralisi" <lpieralisi@kernel.org>,
	"Krzysztof Wilczyński" <kw@linux.com>,
	"Rob Herring" <robh@kernel.org>,
	"Bjorn Helgaas" <bhelgaas@google.com>,
	"Matthias Brugger" <matthias.bgg@gmail.com>,
	"AngeloGioacchino Del Regno"
	<angelogioacchino.delregno@collabora.com>,
	"Huacai Chen" <chenhuacai@kernel.org>,
	"kernel test robot" <lkp@intel.com>
Subject: Re: [PATCH v2 1/1] PCI: mediatek: Correct type for virt_to_phys()
Date: Sat, 16 Sep 2023 13:41:59 +0300	[thread overview]
Message-ID: <ZQWGd/RyKaUBRhUY@smile.fi.intel.com> (raw)
In-Reply-To: <20230914203146.GA77870@bhelgaas>

On Thu, Sep 14, 2023 at 03:31:46PM -0500, Bjorn Helgaas wrote:
> On Thu, Sep 14, 2023 at 10:23:24PM +0300, Andy Shevchenko wrote:

...

> > -	addr = virt_to_phys(port->base + PCIE_MSI_VECTOR);
> > +	addr = virt_to_phys((__force void *)port->base + PCIE_MSI_VECTOR);
> 
> Lots of these drivers use either virt_to_phys() or
> platform_get_resource_byname() to get a physical address that they
> then use as the MSI target.
> 
> But I don't think that's quite right -- the MSI is a DMA transaction
> on PCI, and in general there's no guarantee that bus addresses are
> identical to CPU physical addresses, so shouldn't we use a dma_addr_t
> obtained from the DMA API?
> 
> dw_pcie_msi_host_init() has a complicated version of this that uses
> dmam_alloc_coherent().

Fair enough. I leave it to you then to get it fixed properly.
Consider this as just a heads up for the old report.

-- 
With Best Regards,
Andy Shevchenko



_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2023-09-16 10:42 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-14 19:23 [PATCH v2 1/1] PCI: mediatek: Correct type for virt_to_phys() Andy Shevchenko
2023-09-14 19:23 ` Andy Shevchenko
2023-09-14 20:31 ` Bjorn Helgaas
2023-09-14 20:31   ` Bjorn Helgaas
2023-09-16 10:41   ` Andy Shevchenko [this message]
2023-09-16 10:41     ` Andy Shevchenko
2023-09-18 21:14     ` Bjorn Helgaas
2023-09-18 21:14       ` Bjorn Helgaas

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