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From: Marek Vasut <marek.vasut@gmail.com>
To: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: linux-pci@vger.kernel.org,
	Marek Vasut <marek.vasut+renesas@gmail.com>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Wolfram Sang <wsa@the-dreams.de>,
	linux-renesas-soc@vger.kernel.org
Subject: Re: [PATCH V3 2/3] PCI: rcar: Do not abort on too many inbound dma-ranges
Date: Wed, 16 Oct 2019 17:10:02 +0200
Message-ID: <c4353d63-6f78-92b3-91c9-acc9327e1d80@gmail.com> (raw)
In-Reply-To: <20191016150001.GA7457@e121166-lin.cambridge.arm.com>

On 10/16/19 5:00 PM, Lorenzo Pieralisi wrote:
> On Fri, Aug 09, 2019 at 07:57:40PM +0200, Marek Vasut wrote:
>> From: Marek Vasut <marek.vasut+renesas@gmail.com>
>>
>> In case the "dma-ranges" DT property contains either too many ranges
>> or the range start address is unaligned in such a way that populating
>> the range into the controller requires multiple entries, a situation
>> may occur where all ranges cannot be loaded into the controller.
>>
>> Currently, the driver refuses to probe in such a situation. Relax this
>> behavior, load as many ranges as possible and warn if some ranges do
>> not fit anymore.
> 
> Patches (1) and (3) are fine but I do not think this one is.
> 
> Firmware (DT) should provide dma-ranges according to what HW can handle,
> more so given that other subsystems (eg IOMMU) rely on the dma-ranges
> value to set-up eg DMA - if there is a mismatch between PCI host inbound
> regions and software structures describing DMA'able ranges all bets are
> off.

The firmware provides all the ranges which are available and usable,
that's the hardware description and that should be in the DT. The
firmware cannot decide the policy for the next stage (Linux in this
case) on which ranges are better to use for Linux and which are less
good. Linux can then decide which ranges are best suited for it and
ignore the other ones.

-- 
Best regards,
Marek Vasut

  reply index

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-09 17:57 [PATCH V3 1/3] PCI: rcar: Move the inbound index check marek.vasut
2019-08-09 17:57 ` [PATCH V3 2/3] PCI: rcar: Do not abort on too many inbound dma-ranges marek.vasut
2019-08-16 13:23   ` Simon Horman
2019-08-16 13:28     ` Marek Vasut
2019-08-16 13:38       ` Simon Horman
2019-08-16 17:41         ` Marek Vasut
2019-10-21 10:18       ` Andrew Murray
2019-10-26 18:03         ` Marek Vasut
2019-10-26 20:36           ` Andrew Murray
2019-10-26 21:06             ` Andrew Murray
2019-11-06 23:37             ` Marek Vasut
2019-11-07 14:19               ` Andrew Murray
2019-11-16 15:48                 ` Marek Vasut
2019-11-18 18:42                   ` Robin Murphy
2019-10-16 15:00   ` Lorenzo Pieralisi
2019-10-16 15:10     ` Marek Vasut [this message]
2019-10-16 15:26       ` Lorenzo Pieralisi
2019-10-16 15:29         ` Marek Vasut
2019-10-16 16:18           ` Lorenzo Pieralisi
2019-10-16 18:12             ` Rob Herring
2019-10-16 18:17               ` Marek Vasut
2019-10-16 20:25                 ` Rob Herring
2019-10-16 21:15                   ` Marek Vasut
2019-10-16 22:26                     ` Rob Herring
2019-10-16 22:33                       ` Marek Vasut
2019-10-17  7:06                         ` Geert Uytterhoeven
2019-10-17 10:55                           ` Marek Vasut
2019-10-17 13:06                             ` Robin Murphy
2019-10-17 14:00                               ` Marek Vasut
2019-10-17 14:36                                 ` Rob Herring
2019-10-17 15:01                                   ` Marek Vasut
2019-10-18  9:53                                     ` Lorenzo Pieralisi
2019-10-18 12:22                                       ` Marek Vasut
2019-10-18 12:53                                         ` Robin Murphy
2019-10-18 14:26                                           ` Marek Vasut
2019-10-18 15:44                                             ` Robin Murphy
2019-10-18 16:44                                               ` Marek Vasut
2019-10-18 17:35                                                 ` Robin Murphy
2019-10-18 18:44                                                   ` Marek Vasut
2019-10-21  8:32                                                     ` Geert Uytterhoeven
2019-11-19 12:10                                                     ` Robin Murphy
2019-10-18 10:06                         ` Andrew Murray
2019-10-18 10:17                           ` Geert Uytterhoeven
2019-10-18 11:40                             ` Andrew Murray
2019-08-09 17:57 ` [PATCH V3 3/3] PCI: rcar: Recalculate inbound range alignment for each controller entry marek.vasut
2019-10-21 10:39   ` Andrew Murray
2019-08-16 10:52 ` [PATCH V3 1/3] PCI: rcar: Move the inbound index check Lorenzo Pieralisi
2019-08-16 10:59   ` Marek Vasut
2019-08-16 11:10     ` Lorenzo Pieralisi
2019-10-15 20:14 ` Marek Vasut
2019-10-21 10:11 ` Andrew Murray

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