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From: Stephan Gerhold <stephan@gerhold.net>
To: Douglas Anderson <dianders@chromium.org>
Cc: andersson@kernel.org,
	Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
	konrad.dybcio@somainline.org, sumit.semwal@linaro.org,
	Will Deacon <will@kernel.org>,
	amit.pundir@linaro.org, Sibi Sankar <quic_sibis@quicinc.com>,
	linux-arm-msm@vger.kernel.org, Stephen Boyd <swboyd@chromium.org>,
	linux-arm-kernel@lists.infradead.org,
	Andy Gross <agross@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Konrad Dybcio <konrad.dybcio@linaro.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Rob Clark <robdclark@chromium.org>,
	Rob Herring <robh+dt@kernel.org>,
	cros-qcom-dts-watchers@chromium.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] arm64: dts: qcom: sc7180: Mark SCM as dma-coherent for trogdor
Date: Fri, 16 Jun 2023 09:10:06 +0200	[thread overview]
Message-ID: <ZIwKzozbXxhQHxma@gerhold.net> (raw)
In-Reply-To: <20230615145253.1.Ic62daa649b47b656b313551d646c4de9a7da4bd4@changeid>

On Thu, Jun 15, 2023 at 02:52:54PM -0700, Douglas Anderson wrote:
> Trogdor devices use firmware backed by TF-A instead of Qualcomm's
> normal TZ. On TF-A we end up mapping memory as cachable. Specifically,
> you can see in Trogdor's TF-A code [1] in qti_sip_mem_assign() that we
> call qti_mmap_add_dynamic_region() with MT_RO_DATA. This translates
> down to MT_MEMORY instead of MT_NON_CACHEABLE or MT_DEVICE.
>
> **Apparently Qualcomm's normal TZ implementation maps the memory as
> non-cachable.**

Are you sure about this? From the discussion in the chat the conclusion
was that we can check easily for TF-A, but we have absolutely no idea
what Qualcomm's firmware implementation does. It might be "broken" the
same way and we just have not noticed it yet.

I would perhaps just omit this sentence so we don't risk misleading
someone with information we're not sure about. :)

> 
> Let's add the "dma-coherent" attribute to the SCM for trogdor.
> 

What about sc7280? I guess they use largely the same TF-A firmware?

Thanks,
Stephan

WARNING: multiple messages have this Message-ID (diff)
From: Stephan Gerhold <stephan@gerhold.net>
To: Douglas Anderson <dianders@chromium.org>
Cc: andersson@kernel.org,
	Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
	konrad.dybcio@somainline.org, sumit.semwal@linaro.org,
	Will Deacon <will@kernel.org>,
	amit.pundir@linaro.org, Sibi Sankar <quic_sibis@quicinc.com>,
	linux-arm-msm@vger.kernel.org, Stephen Boyd <swboyd@chromium.org>,
	linux-arm-kernel@lists.infradead.org,
	Andy Gross <agross@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Konrad Dybcio <konrad.dybcio@linaro.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Rob Clark <robdclark@chromium.org>,
	Rob Herring <robh+dt@kernel.org>,
	cros-qcom-dts-watchers@chromium.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] arm64: dts: qcom: sc7180: Mark SCM as dma-coherent for trogdor
Date: Fri, 16 Jun 2023 09:10:06 +0200	[thread overview]
Message-ID: <ZIwKzozbXxhQHxma@gerhold.net> (raw)
In-Reply-To: <20230615145253.1.Ic62daa649b47b656b313551d646c4de9a7da4bd4@changeid>

On Thu, Jun 15, 2023 at 02:52:54PM -0700, Douglas Anderson wrote:
> Trogdor devices use firmware backed by TF-A instead of Qualcomm's
> normal TZ. On TF-A we end up mapping memory as cachable. Specifically,
> you can see in Trogdor's TF-A code [1] in qti_sip_mem_assign() that we
> call qti_mmap_add_dynamic_region() with MT_RO_DATA. This translates
> down to MT_MEMORY instead of MT_NON_CACHEABLE or MT_DEVICE.
>
> **Apparently Qualcomm's normal TZ implementation maps the memory as
> non-cachable.**

Are you sure about this? From the discussion in the chat the conclusion
was that we can check easily for TF-A, but we have absolutely no idea
what Qualcomm's firmware implementation does. It might be "broken" the
same way and we just have not noticed it yet.

I would perhaps just omit this sentence so we don't risk misleading
someone with information we're not sure about. :)

> 
> Let's add the "dma-coherent" attribute to the SCM for trogdor.
> 

What about sc7280? I guess they use largely the same TF-A firmware?

Thanks,
Stephan

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linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2023-06-16  7:10 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-15 21:52 [PATCH] arm64: dts: qcom: sc7180: Mark SCM as dma-coherent for trogdor Douglas Anderson
2023-06-15 21:52 ` Douglas Anderson
2023-06-15 22:23 ` Doug Anderson
2023-06-15 22:23   ` Doug Anderson
2023-06-15 22:25 ` Konrad Dybcio
2023-06-15 22:25   ` Konrad Dybcio
2023-06-16  7:10 ` Stephan Gerhold [this message]
2023-06-16  7:10   ` Stephan Gerhold
2023-06-16 11:20   ` Konrad Dybcio
2023-06-16 11:20     ` Konrad Dybcio
2023-06-16 14:54     ` Stephan Gerhold
2023-06-16 14:54       ` Stephan Gerhold

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