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Message-ID: <88407863-7f7f-aea0-e9b8-4275e667bb4b@quicinc.com>
Date:   Fri, 30 Jun 2023 19:24:42 +0530
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Subject: Re: [PATCH v4 5/6] soc: qcom: Add LLCC support for multi channel DDR
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To:     Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
CC:     Andy Gross <agross@kernel.org>,
        Bjorn Andersson <andersson@kernel.org>,
        Konrad Dybcio <konrad.dybcio@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>,
        <linux-arm-msm@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <devicetree@vger.kernel.org>
References: <20230623141806.13388-1-quic_kbajaj@quicinc.com>
 <20230623141806.13388-6-quic_kbajaj@quicinc.com>
 <CAA8EJpoZiXWDHGEgBF6KuKruQigqdy37pLH1Q_AnXsN6iRPhyA@mail.gmail.com>
 <db8ea67e-529c-856b-026e-2435a2405f6b@quicinc.com>
 <a16b57be-34cd-d093-ac63-d02aef049e51@linaro.org>
From:   Komal Bajaj <quic_kbajaj@quicinc.com>
In-Reply-To: <a16b57be-34cd-d093-ac63-d02aef049e51@linaro.org>
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On 6/28/2023 6:44 PM, Dmitry Baryshkov wrote:
> On 28/06/2023 11:45, Komal Bajaj wrote:
>
> No HTML emails on public mailing lists, please.
>
>>
>>
>> On 6/23/2023 7:56 PM, Dmitry Baryshkov wrote:
>>> On Fri, 23 Jun 2023 at 17:19, Komal Bajaj<quic_kbajaj@quicinc.com>  
>>> wrote:
>>>> Add LLCC support for multi channel DDR configuration
>>>> based on a feature register. Reading DDR channel
>>>> confiuration uses nvmem framework, so select the
>>>> dependency in Kconfig. Without this, there will be
>>>> errors while building the driver with COMPILE_TEST only.
>>>>
>>>> Signed-off-by: Komal Bajaj<quic_kbajaj@quicinc.com>
>>>> ---
>>>>   drivers/soc/qcom/Kconfig     |  2 ++
>>>>   drivers/soc/qcom/llcc-qcom.c | 33 ++++++++++++++++++++++++++++++---
>>>>   2 files changed, 32 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/drivers/soc/qcom/Kconfig b/drivers/soc/qcom/Kconfig
>>>> index a491718f8064..cc9ad41c63aa 100644
>>>> --- a/drivers/soc/qcom/Kconfig
>>>> +++ b/drivers/soc/qcom/Kconfig
>>>> @@ -64,6 +64,8 @@ config QCOM_LLCC
>>>>          tristate "Qualcomm Technologies, Inc. LLCC driver"
>>>>          depends on ARCH_QCOM || COMPILE_TEST
>>>>          select REGMAP_MMIO
>>>> +       select NVMEM
>>> No need to select NVMEM. The used functions are stubbed if NVMEM is 
>>> disabled
>>
>> With the previous patch, where this config was not selected, below 
>> error was flagged by kernel test robot -
>>
>>     drivers/soc/qcom/llcc-qcom.c: In function 'qcom_llcc_get_cfg_index':
>>      >> drivers/soc/qcom/llcc-qcom.c:951:15: error: implicit declaration
>>     of function 'nvmem_cell_read_u8'; did you mean
>>     'nvmem_cell_read_u64'? [-Werror=implicit-function-declaration]
>>           951 |         ret = nvmem_cell_read_u8(&pdev->dev,
>>     "multi_chan_ddr", cfg_index);
>>               |               ^~~~~~~~~~~~~~~~~~
>>               |               nvmem_cell_read_u64
>>         cc1: some warnings being treated as errors
>
> Judging from the rest of nvmem-consumer.h, it appears that not having 
> stubs for this function is an omission. Please fix the header instead.

Okay, I will add the stub for this function in the header.

>
>>
>>>> +       select QCOM_SCM
>>>>          help
>>>>            Qualcomm Technologies, Inc. platform specific
>>>>            Last Level Cache Controller(LLCC) driver for platforms 
>>>> such as,
>>>> diff --git a/drivers/soc/qcom/llcc-qcom.c 
>>>> b/drivers/soc/qcom/llcc-qcom.c
>>>> index 6cf373da5df9..3c29612da1c5 100644
>>>> --- a/drivers/soc/qcom/llcc-qcom.c
>>>> +++ b/drivers/soc/qcom/llcc-qcom.c
>>>> @@ -12,6 +12,7 @@
>>>>   #include <linux/kernel.h>
>>>>   #include <linux/module.h>
>>>>   #include <linux/mutex.h>
>>>> +#include <linux/nvmem-consumer.h>
>>>>   #include <linux/of.h>
>>>>   #include <linux/of_device.h>
>>>>   #include <linux/regmap.h>
>>>> @@ -943,6 +944,19 @@ static int qcom_llcc_cfg_program(struct 
>>>> platform_device *pdev,
>>>>          return ret;
>>>>   }
>>>>
>>>> +static int qcom_llcc_get_cfg_index(struct platform_device *pdev, 
>>>> u8 *cfg_index)
>>>> +{
>>>> +       int ret;
>>>> +
>>>> +       ret = nvmem_cell_read_u8(&pdev->dev, "multi-chan-ddr", 
>>>> cfg_index);
>>>> +       if (ret == -ENOENT) {
>>> || ret == -EOPNOTSUPP ?
>>
>> Okay
>>
>>>> +               *cfg_index = 0;
>>>> +               return 0;
>>>> +       }
>>>> +
>>>> +       return ret;
>>>> +}
>>>> +
>>>>   static int qcom_llcc_remove(struct platform_device *pdev)
>>>>   {
>>>>          /* Set the global pointer to a error code to avoid 
>>>> referencing it */
>>>> @@ -975,11 +989,13 @@ static int qcom_llcc_probe(struct 
>>>> platform_device *pdev)
>>>>          struct device *dev = &pdev->dev;
>>>>          int ret, i;
>>>>          struct platform_device *llcc_edac;
>>>> -       const struct qcom_llcc_config *cfg;
>>>> +       const struct qcom_llcc_config *cfg, *entry;
>>>>          const struct llcc_slice_config *llcc_cfg;
>>>>          u32 sz;
>>>> +       u8 cfg_index;
>>>>          u32 version;
>>>>          struct regmap *regmap;
>>>> +       u32 num_entries = 0;
>>>>
>>>>          drv_data = devm_kzalloc(dev, sizeof(*drv_data), GFP_KERNEL);
>>>>          if (!drv_data) {
>>>> @@ -1040,8 +1056,19 @@ static int qcom_llcc_probe(struct 
>>>> platform_device *pdev)
>>>>
>>>>          drv_data->version = version;
>>>>
>>>> -       llcc_cfg = cfg[0]->sct_data;
>>>> -       sz = cfg[0]->size;
>>>> +       ret = qcom_llcc_get_cfg_index(pdev, &cfg_index);
>>>> +       if (ret)
>>>> +               goto err;
>>>> +
>>>> +       for (entry = cfg; entry->sct_data; entry++, num_entries++)
>>>> +               ;
>>> Please add num_cfgs to the configuration data instead.
>>
>> Shall I create a new wrapper struct having a field num_cfg and a 
>> pointer to those cfgs
>> because configuration data is itself an instance of "struct 
>> qcom_llcc_config" and
>> we can have multiple instances of it.
>
> A wrapper struct is a better approach in my opinion.

Okay, will follow this approach then.

Thanks
Komal
>
>>
>>
>>>> +       if (cfg_index >= num_entries || cfg_index < 0) {
>>> cfg_index is unsigned, so it can not be less than 0.
>>
>> Okay.
>>
>>>> +               ret = -EINVAL;
>>>> +               goto err;
>>>> +       }
>>>> +
>>>> +       llcc_cfg = cfg[cfg_index].sct_data;
>>>> +       sz = cfg[cfg_index].size;
>>>>
>>>>          for (i = 0; i < sz; i++)
>>>>                  if (llcc_cfg[i].slice_id > drv_data->max_slices)
>>>> -- 
>>>> 2.40.1
>>>>
>>
>