ufs-exynos driver enables the shareability option for gs101 which
means the descriptors need to be allocated as cacheable.

Fix the DT node and update bindings to add the dma-coherent property.

This fixes the UFS stability issues we have seen with the upstream
UFS driver.

Note this DT fix can go in independently of the other UFS fixes series
I sent recently [1], as the bootloader already leaves the sharability
bits enabled.

regards,

Peter

[1] https://lore.kernel.org/linux-scsi/20250226220414.343659-1-peter.griffin@linaro.org/

To: André Draszik <andre.draszik@linaro.org>
To: Tudor Ambarus <tudor.ambarus@linaro.org>
To: Rob Herring <robh@kernel.org>
To: Krzysztof Kozlowski <krzk+dt@kernel.org>
To: Conor Dooley <conor+dt@kernel.org>
To: Alim Akhtar <alim.akhtar@samsung.com>
To: Avri Altman <avri.altman@wdc.com>
To: Bart Van Assche <bvanassche@acm.org>
To: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-samsung-soc@vger.kernel.org
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-scsi@vger.kernel.org
Cc: kernel-team@android.com
Cc: willmcvicker@google.com

Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
---
Peter Griffin (2):
      arm64: dts: exynos: gs101: ufs: add dma-coherent property
      scsi: ufs: dt-bindings: exynos: add dma-coherent property for gs101

 Documentation/devicetree/bindings/ufs/samsung,exynos-ufs.yaml | 2 ++
 arch/arm64/boot/dts/exynos/google/gs101.dtsi                  | 1 +
 2 files changed, 3 insertions(+)
---
base-commit: b323d8e7bc03d27dec646bfdccb7d1a92411f189
change-id: 20250314-ufs-dma-coherent-980f2467690d

Best regards,
-- 
Peter Griffin <peter.griffin@linaro.org>

On 3/14/25 8:38 AM, Peter Griffin wrote:
> ufs-exynos driver enables the shareability option for gs101 which
> means the descriptors need to be allocated as cacheable.

Shouldn't that code be modified such that the shareability option is
only set if the dma-coherent property is present in the device tree?

Thanks,

Bart.

Hi Bart,

Thanks for the review.

On Fri, 14 Mar 2025 at 16:01, Bart Van Assche <bvanassche@acm.org> wrote:
>
> On 3/14/25 8:38 AM, Peter Griffin wrote:
> > ufs-exynos driver enables the shareability option for gs101 which
> > means the descriptors need to be allocated as cacheable.
>
> Shouldn't that code be modified such that the shareability option is
> only set if the dma-coherent property is present in the device tree?

Yes, I plan to add an extra patch that does what you describe into the
v2 of the UFS fixes series [1] likely later today.

I sent this out separately for Krzysztof's Exynos DT tree in the hope
he will pick it up in the next -rc as this patch fixes how the driver
is configured today, and is also still the configuration we want once
the driver changes land. I should have made that a bit clearer in the
cover letter :)

Thanks,

Peter

[1] https://lore.kernel.org/linux-scsi/20250226220414.343659-1-peter.griffin@linaro.org/

On 03/14/2025, Bart Van Assche wrote:
> On 3/14/25 8:38 AM, Peter Griffin wrote:
> > ufs-exynos driver enables the shareability option for gs101 which
> > means the descriptors need to be allocated as cacheable.
> 
> Shouldn't that code be modified such that the shareability option is
> only set if the dma-coherent property is present in the device tree?

That's what we do downstream and would fix any issues when booting with an
older DT that doesn't have the `dma-coherent` property set. So I agree that
would be a worthy fix (which I did verify fixes the stability issues).

Regards,
Will

> 
> Thanks,
> 
> Bart.