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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next prev parent reply other threads:[~2023-06-16 7:10 UTC|newest]
Thread overview: 6+ 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 22:23 ` Doug Anderson
2023-06-15 22:25 ` Konrad Dybcio
2023-06-16 7:10 ` Stephan Gerhold [this message]
2023-06-16 11:20 ` Konrad Dybcio
2023-06-16 14:54 ` Stephan Gerhold
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