linux-kernel - Re: [PATCH v2 05/11] clk: qcom: gcc-msm8998: Mark gpu_cfg_ahb

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Date:   Tue, 9 Feb 2021 14:20:00 +0100
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...ainline.org>
To:     Stephen Boyd <sboyd@...nel.org>, linux-arm-msm@...r.kernel.org
Cc:     konrad.dybcio@...ainline.org, marijn.suijten@...ainline.org,
        martin.botka@...ainline.org, phone-devel@...r.kernel.org,
        linux-kernel@...r.kernel.org, agross@...nel.org,
        bjorn.andersson@...aro.org, mturquette@...libre.com,
        robh+dt@...nel.org, linux-clk@...r.kernel.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v2 05/11] clk: qcom: gcc-msm8998: Mark gpu_cfg_ahb_clk as
 critical

Il 08/02/21 19:18, Stephen Boyd ha scritto:
> Quoting AngeloGioacchino Del Regno (2021-01-14 14:10:53)
>> The GPU IOMMU depends on this clock and the hypervisor will crash
>> the SoC if this clock gets disabled because the secure contexts
>> that have been set on this IOMMU by the bootloader will become
>> unaccessible (or they get reset).
>> Mark this clock as critical to avoid this issue when the Adreno
>> GPU is enabled.
>>
>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...ainline.org>
>> ---
>>   drivers/clk/qcom/gcc-msm8998.c | 6 ++++++
>>   1 file changed, 6 insertions(+)
>>
>> diff --git a/drivers/clk/qcom/gcc-msm8998.c b/drivers/clk/qcom/gcc-msm8998.c
>> index c8d4c0348952..afea60a3ef43 100644
>> --- a/drivers/clk/qcom/gcc-msm8998.c
>> +++ b/drivers/clk/qcom/gcc-msm8998.c
>> @@ -2081,6 +2081,12 @@ static struct clk_branch gcc_gpu_cfg_ahb_clk = {
>>                  .hw.init = &(struct clk_init_data){
>>                          .name = "gcc_gpu_cfg_ahb_clk",
>>                          .ops = &clk_branch2_ops,
>> +                       /*
>> +                        * The GPU IOMMU depends on this clock and hypervisor
>> +                        * will crash the SoC if this clock goes down, due to
>> +                        * secure contexts protection.
>> +                        */
>> +                       .flags = CLK_IS_CRITICAL,
>>                  },
>>          },
> 
> Please send a followup patch that hits the branch on at probe time and
> removes this clk from the kernel. That will save some memory and
> overhead of worrying about this clk.
> 

Will do!