Re: [PATCH V5 1/7] soc: qcom: geni: Support for ICC voting

[Matthias Kaehlcke <mka@xxxxxxxxxxxx>]

Hi Akash,

note: my comments below are clearly entering bikeshed territory. Please
take what you agree with and feel free to ignore the rest.

On Fri, May 08, 2020 at 12:03:33PM +0530, Akash Asthana wrote:
> Add necessary macros and structure variables to support ICC BW
> voting from individual SE drivers.
> 
> Signed-off-by: Akash Asthana <akashast@xxxxxxxxxxxxxx>
> ---
> Changes in V2:
>  - As per Bjorn's comment dropped enums for ICC paths, given the three
>    paths individual members
> 
> Changes in V3:
>  - Add geni_icc_get, geni_icc_vote_on and geni_icc_vote_off as helper API.
>  - Add geni_icc_path structure in common header
> 
> Changes in V4:
>  - As per Bjorn's comment print error message in geni_icc_get if return
>    value is not -EPROBE_DEFER.
>  - As per Bjorn's comment remove NULL on path before calling icc_set_bw
>    API.
>  - As per Bjorn's comment drop __func__ print.
>  - As per Matthias's comment, make ICC path a array instead of individual
>    member entry in geni_se struct.
> 
> Note: I have ignored below check patch suggestion because it was throwing
>       compilation error as 'icc_ddr' is not compile time comstant.
> 
> WARNING: char * array declaration might be better as static const
>  - FILE: drivers/soc/qcom/qcom-geni-se.c:726:
>  - const char *icc_names[] = {"qup-core", "qup-config", icc_ddr};
> 
> Changes in V5:
>  - As per Matthias's comment defined enums for ICC paths.
>  - Integrate icc_enable/disable with power on/off call for driver.
>  - As per Matthias's comment added icc_path_names array to print icc path name
>    in failure case.
>  - As per Georgi's suggestion assume peak_bw = avg_bw if not mentioned.
> 
>  drivers/soc/qcom/qcom-geni-se.c | 92 +++++++++++++++++++++++++++++++++++++++++
>  include/linux/qcom-geni-se.h    | 42 +++++++++++++++++++
>  2 files changed, 134 insertions(+)
> 
> diff --git a/drivers/soc/qcom/qcom-geni-se.c b/drivers/soc/qcom/qcom-geni-se.c
> index 7d622ea..63403bf 100644
> --- a/drivers/soc/qcom/qcom-geni-se.c
> +++ b/drivers/soc/qcom/qcom-geni-se.c
> @@ -92,6 +92,9 @@ struct geni_wrapper {
>  	struct clk_bulk_data ahb_clks[NUM_AHB_CLKS];
>  };
>  
> +static const char * const icc_path_names[] = {"qup-core", "qup-config",
> +								"qup-memory"};

nit: the indentation is a bit odd. I would align it either with "qup-core" or
at a tab stop nearby.

> +
>  #define QUP_HW_VER_REG			0x4
>  
>  /* Common SE registers */
> @@ -720,6 +723,95 @@ void geni_se_rx_dma_unprep(struct geni_se *se, dma_addr_t iova, size_t len)
>  }
>  EXPORT_SYMBOL(geni_se_rx_dma_unprep);
>  
> +int geni_icc_get(struct geni_se *se, const char *icc_ddr)
> +{
> +	int i, icc_err;

nit: the 'icc_' prefix doesn't add value here, just 'err' would be less
'noisy' IMO.

> +	const char *icc_names[] = {"qup-core", "qup-config", icc_ddr};

nit: you could avoid repeating the first to strings by referencing
icc_path_names[GENI_TO_CORE] and icc_path_names[CPU_TO_GENI]. Not sure
if it's really better, it avoids the redundant names, but is slightly
less readable.

> +
> +	for (i = 0; i < ARRAY_SIZE(se->icc_paths); i++) {
> +		if (!icc_names[i])
> +			continue;
> +
> +		se->icc_paths[i].path = devm_of_icc_get(se->dev, icc_names[i]);
> +		if (IS_ERR(se->icc_paths[i].path))
> +			goto icc_get_failure;

nit: since there is only a single label it isn't really necessary to be so
precise. 'goto err' is very common in the kernel, 'err_icc_get' would be
another alternative.

> +	}
> +
> +	return 0;
> +
> +icc_get_failure:
> +	icc_err = PTR_ERR(se->icc_paths[i].path);
> +	if (icc_err != -EPROBE_DEFER)
> +		dev_err_ratelimited(se->dev, "Failed to get ICC path:%s, ret:%d\n",

All the logs in this patch result in something like "... path:qup-core, ret:42".
For humans I think it is more intuitive to parse "... path 'qup-core': 42".

Reviewed-by: Matthias Kaehlcke <mka@xxxxxxxxxxxx>