Re: [PATCH v3 06/10] soc: qcom: Add LLCC support for multi channel DDR

[Komal Bajaj]

On 6/13/2023 10:41 PM, Bjorn Andersson wrote:
> On Fri, May 12, 2023 at 05:51:30PM +0530, Komal Bajaj wrote:
> > Add LLCC support for multi channel DDR configuration
> > based on a feature register.
> >
> > Signed-off-by: Komal Bajaj <quic_kbajaj@xxxxxxxxxxx>
> > ---
> >   drivers/soc/qcom/llcc-qcom.c | 32 +++++++++++++++++++++++++++++---
> >   1 file changed, 29 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/soc/qcom/llcc-qcom.c b/drivers/soc/qcom/llcc-qcom.c
> > index 6cf373da5df9..1da337e7a378 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 = 0;
> First use is an assignment, no need to initialize here.

Noted.

> > +
> > +	ret = nvmem_cell_read_u8(&pdev->dev, "multi_chan_ddr", cfg_index);
> > +	if (ret == -ENOENT) {
> > +		*cfg_index = 0;
> Does nvmem_cell_read_u8() cahnge cfg_index when it fails with -ENOENT?

No, if nvmem_cell_read_u8() fails with any error, cfg_index will not be 
changed.

Thanks
Komal
> > +		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 +1056,18 @@ 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++);
> This is not readable, move the increment of num_entries out of there.
>
> > +	if (cfg_index >= num_entries || cfg_index < 0) {
> How can cfg_index be negative?
>
> Regards,
> Bjorn
>
> > +		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)
> > --
> > 2.17.1