Re: [PATCH V2 2/2] firmware: arm_scmi: Skip adding bad duplicates

[Konrad Dybcio <konradybcio@kernel.org>]

On 4.09.2024 5:13 AM, Sibi Sankar wrote:
> Ensure that the bad duplicates reported by the platform firmware doesn't
> get added to the opp-tables.
> 
> Signed-off-by: Sibi Sankar <quic_sibis@quicinc.com>
> ---
>  drivers/firmware/arm_scmi/perf.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/firmware/arm_scmi/perf.c b/drivers/firmware/arm_scmi/perf.c
> index 2d77b5f40ca7..114c3dd70ede 100644
> --- a/drivers/firmware/arm_scmi/perf.c
> +++ b/drivers/firmware/arm_scmi/perf.c
> @@ -386,9 +386,11 @@ process_response_opp(struct device *dev, struct perf_dom_info *dom,
>  		le16_to_cpu(r->opp[loop_idx].transition_latency_us);
>  
>  	ret = xa_insert(&dom->opps_by_lvl, opp->perf, opp, GFP_KERNEL);
> -	if (ret)
> +	if (ret) {
>  		dev_warn(dev, "Failed to add opps_by_lvl at %d for %s - ret:%d\n",
>  			 opp->perf, dom->info.name, ret);
> +		opp->perf = 0;
> +	}
>  }
>  
>  static inline void
> @@ -404,9 +406,12 @@ process_response_opp_v4(struct device *dev, struct perf_dom_info *dom,
>  		le16_to_cpu(r->opp[loop_idx].transition_latency_us);
>  
>  	ret = xa_insert(&dom->opps_by_lvl, opp->perf, opp, GFP_KERNEL);
> -	if (ret)
> +	if (ret) {
>  		dev_warn(dev, "Failed to add opps_by_lvl at %d for %s - ret:%d\n",
>  			 opp->perf, dom->info.name, ret);
> +		opp->perf = 0;
> +		return;
> +	}
>  
>  	/* Note that PERF v4 reports always five 32-bit words */
>  	opp->indicative_freq = le32_to_cpu(r->opp[loop_idx].indicative_freq);
> @@ -871,6 +876,10 @@ static int scmi_dvfs_device_opps_add(const struct scmi_protocol_handle *ph,
>  		else
>  			freq = dom->opp[idx].indicative_freq * dom->mult_factor;
>  
> +		/* Skip all invalid frequencies reported by the firmware */
> +		if (!freq)
> +			continue;

Maybe something like this instead? (not tested)

diff --git a/drivers/firmware/arm_scmi/perf.c b/drivers/firmware/arm_scmi/perf.c
index 2d77b5f40ca7..530692119c79 100644
--- a/drivers/firmware/arm_scmi/perf.c
+++ b/drivers/firmware/arm_scmi/perf.c
@@ -431,8 +431,14 @@ iter_perf_levels_process_response(const struct scmi_protocol_handle *ph,
 {
        struct scmi_opp *opp;
        struct scmi_perf_ipriv *p = priv;
+       unsigned int idx = st->desc_index + st->loop_idx;
+
+       opp = &p->perf_dom->opp[idx];
+
+       /* Avoid duplicate entries coming from buggy firmware */
+       if (idx > 0 && opp->perf && p->perf_dom->opp[idx - 1].perf)
+               return 0;
 
-       opp = &p->perf_dom->opp[st->desc_index + st->loop_idx];
        if (PROTOCOL_REV_MAJOR(p->version) <= 0x3)
                process_response_opp(ph->dev, p->perf_dom, opp, st->loop_idx,
                                     response);

Konrad