Re: [PATCH] dra7: sata: Fix SATA with CONFIG_ARM_LPAE enabled

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On 05/03/2020 12:05 pm, Roger Quadros wrote:
Tony, Christoph,

On 04/03/2020 18:20, Tony Lindgren wrote:
* Roger Quadros <rogerq@xxxxxx> [200304 09:01]:
Even though the TRM says that SATA IP has 36 address bits
wired in the SoC, we see bus errors whenever any address
greater than 32-bit is given to the controller.

This happens on dra7-EVM with 4G of RAM with CONFIG_ARM_LPAE=y.

As a workaround we limit the DMA address range to 32-bits
for SATA.

Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Robin Murphy <robin.murphy@xxxxxxx>
Cc: Rob Herring <robh+dt@xxxxxxxxxx>
Reported-by: Yan Liu <yan-liu@xxxxxx>
Signed-off-by: Roger Quadros <rogerq@xxxxxx>
---

NOTE: Currently ARM dma-mapping code doesn't account for devices
bus_dma_limit. This is fixed in [1].

[1] https://lkml.org/lkml/2020/2/18/712

So is this dts patch safe to apply without the series above?


Yes. To my surprise this patch fixes the SATA issue even without [1].
Without this patch dev->bus_dma_limit was being set to 0 and with the patch
it is being set to 0xffffffff.

Right - LPAE configs should be getting dma-direct ops since 5.3, which already respect the limit. For non-LPAE configs it means you go from being broken from having no limit at all, to having a limit set but not respected, which is still equally broken, but no *more* so than before.

Robin.

And should this dts patch be applied as a fix or can it wait
until the merge window?

I think we should mark it for stable and apply it right away as fix for v5.6.

Cc: stable@xxxxxxxxxx

cheers,
-roger

Regards,

Tony

  arch/arm/boot/dts/dra7.dtsi | 25 ++++++++++++++++---------
  1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/arch/arm/boot/dts/dra7.dtsi b/arch/arm/boot/dts/dra7.dtsi
index d78b684e7fca..895462c22d1c 100644
--- a/arch/arm/boot/dts/dra7.dtsi
+++ b/arch/arm/boot/dts/dra7.dtsi
@@ -642,15 +642,22 @@
          };
          /* OCP2SCP3 */
-        sata: sata@4a141100 {
-            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 = <1>;
+            #size-cells = <2>;
+            compatible = "simple-bus";
+            ranges = <0x0 0x4a140000 0x0 0x1200>;
+            dma-ranges = <0x0 0x0 0x1 0x00000000>;
+            sata: sata@4a141100 {
+                compatible = "snps,dwc-ahci";
+                reg = <0x0 0x0 0x1100>, <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 */
--
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