linux-kernel - Re: [PATCH v5 0/4] nvmem: qfprom: Patches for fuse blowing on Qualcomm SoCs

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Date:   Mon, 20 Jul 2020 10:05:03 +0100
From:   Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:     Douglas Anderson <dianders@...omium.org>,
        Rob Herring <robh+dt@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Andy Gross <agross@...nel.org>
Cc:     sparate@...eaurora.org, saiprakash.ranjan@...eaurora.org,
        mturney@...eaurora.org, linux-arm-msm@...r.kernel.org,
        Jeffrey Hugo <jhugo@...eaurora.org>, dhavalp@...eaurora.org,
        rnayak@...eaurora.org, mkurumel@...eaurora.org,
        Ravi Kumar Bokka <rbokka@...eaurora.org>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 0/4] nvmem: qfprom: Patches for fuse blowing on
 Qualcomm SoCs



On 10/07/2020 15:35, Douglas Anderson wrote:
> This series enables blowing of fuses on Qualcomm SoCs by extending the
> existing qfprom driver with write support.
> 
> A few notes:
> - Though I don't have any firsthand knowledge of it, it's my
>    understanding that these changes could be used on any Qualcomm SoC.
>    However, it's likely not very useful on most boards because the
>    bootloader protects against this.  Thus the write support here is
>    likely only useful with a cooperating bootloader.
> - Blowing fuses is truly a one-way process.  If you mess around with
>    this and do something wrong you could irreparably brick your chip.
>    You have been warned.
> 
> Versions 1 and 2 of this series were posted by Ravi Kumar Bokka.  I
> posted version 3 containing my changes / fixups with his consent.  I
> have left authorship as Ravi but added my own Signed-off-by.
> 
> Version 4 is a minor spin over version 3.
> 
> Version 5 is an even more minor spin and just bumps up some timings to
> fix a failure reported by Ravi on one device.  I've collected Rob
> Herring's reviews and (as far as I know) this is ready to land.
> 
> Changes in v5:
> - QFPROM_FUSE_BLOW_POLL_US 10 => 100
> - QFPROM_FUSE_BLOW_TIMEOUT_US 100 => 1000
> 
> Changes in v4:
> - Maintainer now listed as Srinivas.
> - Example under "soc" to get #address-cells and #size-cells.
> - Clock name is "core", not "sec".
> - Example under "soc" to get #address-cells and #size-cells.
> - Only get clock/regulator if all address ranges are provided.
> - Don't use optional version of clk_get now.
> - Clock name is "core", not "sec".
> - Cleaned up error message if couldn't get clock.
> - Fixed up minor version mask.
> - Use GENMASK to generate masks.
> - Clock name is "core", not "sec".
> 
> Changes in v3:
> - Split conversion to yaml into separate patch new in v3.
> - Use 'const' for compatible instead of a 1-entry enum.
> - Changed filename to match compatible string.
> - Add #address-cells and #size-cells to list of properties.
> - Fixed up example.
> - Add an extra reg range (at 0x6000 offset for SoCs checked)
> - Define two options for reg: 1 item or 4 items.
> - No reg-names.
> - Add "clocks" and "clock-names" to list of properties.
> - Clock is now "sec", not "secclk".
> - Add "vcc-supply" to list of properties.
> - Fixed up example.
> - Don't provide "reset" value for things; just save/restore.
> - Use the major/minor version read from 0x6000.
> - Reading should still read "corrected", not "raw".
> - Added a sysfs knob to allow you to read "raw" instead of "corrected"
> - Simplified the SoC data structure.
> - No need for quite so many levels of abstraction for clocks/regulator.
> - Don't set regulator voltage.  Rely on device tree to make sure it's right.
> - Properly undo things in the case of failure.
> - Don't just keep enabling the regulator over and over again.
> - Enable / disable the clock each time
> - Polling every 100 us but timing out in 10 us didn't make sense; swap.
> - No reason for 100 us to be SoC specific.
> - No need for reg-names.
> - We shouldn't be creating two separate nvmem devices.
> - Name is now 'efuse' to match what schema checker wants.
> - Reorganized ranges to match driver/bindings changes.
> - Added 4th range as per driver/binding changes.
> - No more reg-names as per driver/binding changes.
> - Clock name is now just "sec" as per driver/binding changes.
> 
> Ravi Kumar Bokka (4):
>    dt-bindings: nvmem: qfprom: Convert to yaml
>    dt-bindings: nvmem: Add properties needed for blowing fuses
>    nvmem: qfprom: Add fuse blowing support

Applied above 3 with merge conflict fixed.
dts patches should go via arm-soc tree, Bjorn could pick that up!


Thanks,
srini
>    arm64: dts: qcom: sc7180: Add properties to qfprom for fuse blowing
> 
>   .../bindings/nvmem/qcom,qfprom.yaml           |  96 ++++++
>   .../devicetree/bindings/nvmem/qfprom.txt      |  35 --
>   arch/arm64/boot/dts/qcom/sc7180-idp.dts       |   4 +
>   arch/arm64/boot/dts/qcom/sc7180.dtsi          |  10 +-
>   drivers/nvmem/qfprom.c                        | 314 +++++++++++++++++-
>   5 files changed, 411 insertions(+), 48 deletions(-)
>   create mode 100644 Documentation/devicetree/bindings/nvmem/qcom,qfprom.yaml
>   delete mode 100644 Documentation/devicetree/bindings/nvmem/qfprom.txt
>