linux-kernel - Re: [PATCH v4 5/6] soc: qcom: Add LLCC support for multi channel DDR

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Date:   Fri, 23 Jun 2023 17:26:34 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Komal Bajaj <quic_kbajaj@...cinc.com>
Cc:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v4 5/6] soc: qcom: Add LLCC support for multi channel DDR

On Fri, 23 Jun 2023 at 17:19, Komal Bajaj <quic_kbajaj@...cinc.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@...cinc.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

> +       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 ?

> +               *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.

> +       if (cfg_index >= num_entries || cfg_index < 0) {

cfg_index is unsigned, so it can not be less than 0.

> +               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
>


-- 
With best wishes
Dmitry