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Message-ID: <3d8ea578-2ecb-1126-3bf0-2dc695687245@ti.com>
Date: Wed, 26 Feb 2020 13:33:48 +0200
From: Roger Quadros <rogerq@...com>
To: Robin Murphy <robin.murphy@....com>,
Rob Herring <robh+dt@...nel.org>
CC: Christoph Hellwig <hch@....de>,
Péter Ujfalusi <peter.ujfalusi@...com>,
Murali Karicheri <m-karicheri2@...com>,
"Nori, Sekhar" <nsekhar@...com>, "Anna, Suman" <s-anna@...com>,
Stefan Wahren <stefan.wahren@...e.com>,
Andreas Färber <afaerber@...e.de>,
Hans Verkuil <hverkuil@...all.nl>,
<devicetree@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Nishanth Menon <nm@...com>,
"hdegoede@...hat.com" <hdegoede@...hat.com>,
Vignesh Raghavendra <vigneshr@...com>
Subject: Re: dma_mask limited to 32-bits with OF platform device
Hi,
On 19/02/2020 17:25, Robin Murphy wrote:
> On 19/02/2020 2:29 pm, Roger Quadros wrote:
>> Rob,
>>
>> On 18/02/2020 19:22, Rob Herring wrote:
>>> On Tue, Feb 18, 2020 at 2:28 AM Roger Quadros <rogerq@...com> wrote:
>>>>
>>>> Chrishtoph,
>>>>
>>>> The branch works fine for SATA on DRA7 with CONFIG_LPAE once I
>>>> have the below DT fix.
>>>>
>>>> Do you intend to send these fixes to -stable?
>>>>
>>>> ------------------------- arch/arm/boot/dts/dra7.dtsi -------------------------
>>>> index d78b684e7fca..853ecf3cfb37 100644
>>>> @@ -645,6 +645,8 @@
>>>> sata: sata@...41100 {
>>>> compatible = "snps,dwc-ahci";
>>>> reg = <0x4a140000 0x1100>, <0x4a141100 0x7>;
>>>> + #size-cells = <2>;
>>>> + dma-ranges = <0x00000000 0x00000000 0x1 0x00000000>;
>>>
>>> dma-ranges should be in the parent (bus) node, not the device node.
>>
>> I didn't understand why.
>>
>> There are many devices on the parent bus node and all devices might not have the 32-bit DMA limit
>> the SATA controller has.
>>
>> SATA controller is the bus master and the ATA devices are children of the SATA controller.
>
> But SATA is not a memory-mapped bus - in the context of MMIO, the AHCI is the bus-master device, not a bridge or level of interconnect. The DeviceTree spec[1] clearly defines dma-ranges as an address translation between a "parent bus" and a "child bus".
>
> If in the worst case this address-limited interconnect really only exists between the AHCI's master interface and everything else in the system, then you'll have to describe it explicitly to meet DT's expectation of a "bus" (e.g. [2]). Yes, it's a bit clunky, but any scheme has its edge cases.
>
>> From Documentation/devicetree/booting-without-of.txt
>>
>> * DMA Bus master
>> Optional property:
>> - dma-ranges: <prop-encoded-array> encoded as arbitrary number of triplets of
>> (child-bus-address, parent-bus-address, length). Each triplet specified
>> describes a contiguous DMA address range.
>> The dma-ranges property is used to describe the direct memory access (DMA)
>> structure of a memory-mapped bus whose device tree parent can be accessed
>> from DMA operations originating from the bus. It provides a means of
>> defining a mapping or translation between the physical address space of
>> the bus and the physical address space of the parent of the bus.
>> (for more information see the Devicetree Specification)
>>
>> * DMA Bus child
>> Optional property:
>> - dma-ranges: <empty> value. if present - It means that DMA addresses
>> translation has to be enabled for this device.
>
> Disregarding that this was apparently never in ePAPR, so not grandfathered in to DTSpec, and effectively nobody ever has actually followed it (oh, if only...), note "<empty>" - that still doesn't imply that a *non-empty* dma-ranges would be valid on device nodes.
>
> Robin.
>
> [1] https://www.devicetree.org/specifications/
> [2] https://lore.kernel.org/lkml/20181010120737.30300-20-laurentiu.tudor@nxp.com/
With the patch (in the end). dev->bus_dma_limit is still set to 0 and so is not being used.
from of_dma_configure()
ret = of_dma_get_range(np, &dma_addr, &paddr, &size);
...
/* ...but only set bus limit if we found valid dma-ranges earlier */
if (!ret)
dev->bus_dma_limit = end;
There is no other place bus_dma_limit is set. Looks like every device should inherit that
from it's parent right?
diff --git a/arch/arm/boot/dts/dra7.dtsi b/arch/arm/boot/dts/dra7.dtsi
index 64a0f90f5b52..5418c31d4da7 100644
--- a/arch/arm/boot/dts/dra7.dtsi
+++ b/arch/arm/boot/dts/dra7.dtsi
@@ -680,15 +680,22 @@
};
/* OCP2SCP3 */
- sata: sata@...41100 {
- compatible = "snps,dwc-ahci";
- reg = <0x4a140000 0x1100>, <0x4a141100 0x7>;
- interrupts = <GIC_SPI 49 IRQ_TYPE_LEVEL_HIGH>;
- phys = <&sata_phy>;
- phy-names = "sata-phy";
- clocks = <&l3init_clkctrl DRA7_L3INIT_SATA_CLKCTRL 8>;
- ti,hwmods = "sata";
- ports-implemented = <0x1>;
+ sata_aux_bus {
+ #address-cells = <2>;
+ #size-cells = <2>;
+ compatible = "simple-bus";
+ ranges = <0x0 0x0 0x4a140000 0x0 0x1200>;
+ dma-ranges = <0x0 0x0 0x0 0x0 0x1 0x00000000>;
+ sata: sata@...41100 {
+ compatible = "snps,dwc-ahci";
+ reg = <0x0 0x0 0x0 0x1100>, <0x0 0x1100 0x0 0x7>;
+ interrupts = <GIC_SPI 49 IRQ_TYPE_LEVEL_HIGH>;
+ phys = <&sata_phy>;
+ phy-names = "sata-phy";
+ clocks = <&l3init_clkctrl DRA7_L3INIT_SATA_CLKCTRL 8>;
+ ti,hwmods = "sata";
+ ports-implemented = <0x1>;
+ };
};
/* OCP2SCP1 */
--
cheers,
-roger
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
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