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From: Trilok Soni <quic_tsoni@quicinc.com>
To: Stephen Boyd <swboyd@chromium.org>,
	Andy Gross <agross@kernel.org>,
	"Bjorn Andersson" <bjorn.andersson@linaro.org>,
	Rob Herring <robh+dt@kernel.org>,
	"Sai Prakash Ranjan" <saiprakash.ranjan@codeaurora.org>
Cc: <devicetree@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-kernel@vger.kernel.org>, <linux-arm-msm@vger.kernel.org>,
	"Rajendra Nayak" <rnayak@codeaurora.org>,
	Sibi Sankar <sibis@codeaurora.org>, <quic_eberman@quicinc.com>
Subject: Re: [PATCH 0/3] soc: qcom: Add download mode support for QTI platforms
Date: Thu, 12 Aug 2021 21:31:08 -0700	[thread overview]
Message-ID: <0178821e-a8cd-87c8-640c-4928201a3b5a@quicinc.com> (raw)
In-Reply-To: <CAE-0n52PzadMxB_4h2DGJGLO++Bu_PCSsxS8NHe+cuhv=Mw0sA@mail.gmail.com>

Stephen,

On 8/12/2021 5:16 PM, Stephen Boyd wrote:
> Quoting Sai Prakash Ranjan (2021-08-12 02:17:39)
>> Collecting ramdumps on QTI platforms mainly require two things,
>> SDI (System Debug Image) enabled firmware and kernel support to
>> configure download mode cookies and SDI settings. Ramdumps can
>> be collected once the system enters the download mode. To enter
>> download mode, magic values or cookies need to be set in IMEM
>> which is used by firmware to decide to enter download mode or not.
>> Download mode cookies remain the same across targets and SDI disable
>> register needs to be set or SDI needs to be disabled in case of normal
>> reboot since ramdumps are supposed to be for crash debugging and
>> not for every reboot. This series adds the kernel support required
>> to enter download mode.
> 
> I don't recall if we discussed this on the list, but I'd really prefer
> that we don't make kernel changes to support this beyond implementing
> PSCI SYSTEM_RESET2 support and then some sort of vendor specific (or if
> ARM is willing to update the spec then ARM specific) reset command on
> panic reboot paths. The idea is to set the cookie in the bootloader
> before the kernel is booted, then any insta-reboots/watchdogs would go
> into download mode, no special init code required to lay down the cookie
>>   create mode 100644 drivers/soc/qcom/download_mode.c

Some discussion by Elliot on the PSCI_SYSTEM_RESET2 and vendor bits was 
done here. You may want to check.

https://lkml.org/lkml/2020/2/24/1137

---Trilok Soni

  reply	other threads:[~2021-08-13  4:31 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-12  9:17 Sai Prakash Ranjan
2021-08-12  9:17 ` [PATCH 1/3] soc: qcom: Add download mode support Sai Prakash Ranjan
2021-08-12  9:17 ` [PATCH 2/3] dt-bindings: msm: Add QTI download mode support binding Sai Prakash Ranjan
2021-08-17 21:28   ` Rob Herring
2021-08-18  3:36     ` Sai Prakash Ranjan
2021-08-12  9:17 ` [PATCH 3/3] arm64: dts: qcom: sc7180: Add IMEM, pil info and download mode region Sai Prakash Ranjan
2021-09-27 22:56   ` (subset) " Bjorn Andersson
2021-08-13  0:16 ` [PATCH 0/3] soc: qcom: Add download mode support for QTI platforms Stephen Boyd
2021-08-13  4:31   ` Trilok Soni [this message]
2021-08-16 10:38   ` Sai Prakash Ranjan

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