linux-kernel - Re: [PATCH v2 1/3] soc: qcom: llcc: Pass SoC specific EDAC register offsets to EDAC driver

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Message-ID: <8a8d52db-b489-61ae-4057-3af1e91b638b@quicinc.com>
Date:   Wed, 24 Aug 2022 18:37:36 +0530
From:   Sai Prakash Ranjan <quic_saipraka@...cinc.com>
To:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
CC:     <bjorn.andersson@...aro.org>, <bp@...en8.de>, <mchehab@...nel.org>,
        <james.morse@....com>, <rric@...nel.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-edac@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <quic_tsoni@...cinc.com>
Subject: Re: [PATCH v2 1/3] soc: qcom: llcc: Pass SoC specific EDAC register
 offsets to EDAC driver

On 8/24/2022 6:27 PM, Manivannan Sadhasivam wrote:
> On Wed, Aug 24, 2022 at 10:43:51AM +0530, Sai Prakash Ranjan wrote:
>> On 8/23/2022 9:01 PM, Manivannan Sadhasivam wrote:
>>> On Mon, Aug 22, 2022 at 05:29:13PM +0530, Sai Prakash Ranjan wrote:
>>>> Hi Mani,
>>>>
>>>> On 8/12/2022 11:36 AM, Manivannan Sadhasivam wrote:
>>>>> The LLCC EDAC register offsets varies between each SoCs. Until now, the
>>>>> EDAC driver used the hardcoded register offsets. But this caused crash
>>>>> on SM8450 SoC where the register offsets has been changed.
>>>>>
>>>>> So to avoid this crash and also to make it easy to accomodate changes for
>>>>> new SoCs, let's pass the SoC specific register offsets to the EDAC driver.
>>>>>
>>>>> Currently, two set of offsets are used. One is SM8450 specific and another
>>>>> one is common to all SoCs.
>>>>>
>>>>> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
>>>> <snip> ...
>>>>
>>>>>     static const struct qcom_llcc_config sm8350_cfg = {
>>>>> @@ -309,6 +370,7 @@ static const struct qcom_llcc_config sm8350_cfg = {
>>>>>     	.size           = ARRAY_SIZE(sm8350_data),
>>>>>     	.need_llcc_cfg	= true,
>>>>>     	.reg_offset	= llcc_v1_2_reg_offset,
>>>>> +	.edac_reg	= &common_edac_reg,
>>>>>     };
>>>>>     static const struct qcom_llcc_config sm8450_cfg = {
>>>>> @@ -316,6 +378,7 @@ static const struct qcom_llcc_config sm8450_cfg = {
>>>>>     	.size           = ARRAY_SIZE(sm8450_data),
>>>>>     	.need_llcc_cfg	= true,
>>>>>     	.reg_offset	= llcc_v21_reg_offset,
>>>>> +	.edac_reg	= &sm8450_edac_reg,
>>>>>     };
>>>>>
>>>> Can we have LLCC version specific register offsets instead of SoC specific similar to reg_offset callbacks?
>>>> For SM8450, it would be llcc_v21_edac_reg and for others llcc_v1_2_edac_reg instead of common_edac_reg.
>>>> common_edac_reg is very general and is not exactly common for all, its just common for SoCs with same LLCC.
>>>>
>>> I thought about it but I was not sure if rest of the SoCs are using version
>>> v1.2. I know that reg_offset uses v1.2 but I was skeptical and hence used the
>>> SoC specific offsets.
>>>
>>> Can you confirm if rest of the SoCs are using v1.2?
>> LLCC versioning follows w.x.y.z format and w and y are major and minor versions based
>> on which the naming for reg_offsets is chosen.
>>
>> Now in above reg_offsets, llcc_v1_2 is not v1.2, it means v1.0 or v2.0 where 1, 2 is a major version
>> and 0 is a minor version. llcc_v21 is actually v2.1 where 2 is a major and 1 is a minor version.
>> I know the naming is pretty bad, should probably replace llcc_v1_2 with llcc_v1_0_v2_0 and
>> llcc_v21 with llcc_v2_1? Note here minor version is important because SM8350 is v2.0 and uses
>> old reg offsets.
>>
> Yeah it is confusing. I think we should just use the base LLCC version
> that got changed with the previous one and add a comment on top of the
> definition. For instance, all of the SoCs before SM8450 should use
> llcc_v1_reg_offset since the LLCC version starts from v1.0.0 and SM8450 should
> use llcc_v2_1_reg_offset since it supports the LLCC reg offset that got changed
> since v2.1.0. Thoughts?

Ya sounds good, only exception is SM8350 which is v2.0 but will be using v1 in naming but I guess its OK.

Thanks,
Sai

> Thanks,
> Mani
>
>> So coming to your query now, all other SoCs except SM8450(which uses v2.1) are using LLCC v1.0
>> or v2.0, so it is valid to use the same logic as reg_offsets for edac_reg.
>>
>> Thanks,
>> Sai
>>
>>> Thanks,
>>> Mani
>>>
>>>> Version based is more applicable as multiple SoCs might use same LLCC versions and would reduce SoC specific data
>>>> which would be needed for every SoC in case some newer LLCC comes out. I know you could just call sm8450_edac_reg
>>>> for lets say sm8550 or so on to reduce duplication but that won't look good.
>>>>
>>>>
>>>> Thanks,
>>>> Sai