Re: dma_mask limited to 32-bits with OF platform device

Hi,

On 03/03/2020 21:26, Rob Herring wrote:

On Tue, Mar 3, 2020 at 8:06 AM Robin Murphy [off-list ref] wrote:

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On 03/03/2020 8:27 am, Roger Quadros wrote:
[...]

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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?

Any ideas how to expect this to work?

Is of_dma_get_range() actually succeeding, or is it tripping up on some
aspect of the DT (in which case there should be errors in the log)?

of_dma_get_range() was failing but no errors in the log.

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Looking again at the fragment below, are you sure it's correct? It
appears to me like it might actually be defining a 1-byte-long DMA
range, which indeed I wouldn't really expect to work.

Indeed, though it took me a minute to see why.

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Robin.

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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@4a141100 {
-            compatible = "snps,dwc-ahci";
-            reg = <0x4a140000 0x1100>, <0x4a141100 0x7>;

Based on this, the parent address size is 1 cell...

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-            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>;

So this is:
child addr: 0x0 0x0
parent addr: 0x0
size: 0x0 0x1

Good catch.
So I fixed it to

	dma-ranges = <0x0 0x0 0x0 0x1 0x00000000>;

And now it works :).
Thanks!

The last cell is just ignored I guess if you aren't seeing any errors.
We check this in dtc for ranges, but not dma-ranges. So I'm fixing
that.

Great!

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+            sata: sata@4a141100 {
+                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
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