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

[Dmitry Baryshkov]

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@xxxxxxxxxxx>  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@xxxxxxxxxxx>
> > > ---
> > >   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.

> > > +       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.

> > > +       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

--
With best wishes
Dmitry