Re: [PATCH v6 5/6] media: venus: core: Add support for opp tables/perf voting

[Stanimir Varbanov <stanimir.varbanov@linaro.org>]

Hi Rajendra,

On 6/15/20 3:02 PM, Rajendra Nayak wrote:
> Add support to add OPP tables and perf voting on the OPP powerdomain.
> This is needed so venus votes on the corresponding performance state
> for the OPP powerdomain along with setting the core clock rate.
> 
> Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org>
> Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
> Cc: Stanimir Varbanov <stanimir.varbanov@linaro.org>
> Cc: linux-media@vger.kernel.org
> ---
> No functional change in v6, rebased over 5.8-rc1
> Bindings update to add optional PD https://lore.kernel.org/patchwork/patch/1241077/
> 
>  drivers/media/platform/qcom/venus/core.c       | 43 +++++++++++++++++---
>  drivers/media/platform/qcom/venus/core.h       |  5 +++
>  drivers/media/platform/qcom/venus/pm_helpers.c | 54 ++++++++++++++++++++++++--
>  3 files changed, 92 insertions(+), 10 deletions(-)
> 

<cut>

>  
> @@ -740,13 +740,16 @@ static int venc_power_v4(struct device *dev, int on)
>  
>  static int vcodec_domains_get(struct device *dev)
>  {
> +	int ret;
> +	struct opp_table *opp_table;
> +	struct device **opp_virt_dev;
>  	struct venus_core *core = dev_get_drvdata(dev);
>  	const struct venus_resources *res = core->res;
>  	struct device *pd;
>  	unsigned int i;
>  
>  	if (!res->vcodec_pmdomains_num)
> -		return -ENODEV;
> +		goto skip_pmdomains;
>  
>  	for (i = 0; i < res->vcodec_pmdomains_num; i++) {
>  		pd = dev_pm_domain_attach_by_name(dev,
> @@ -763,7 +766,41 @@ static int vcodec_domains_get(struct device *dev)
>  	if (!core->pd_dl_venus)
>  		return -ENODEV;
>  
> +skip_pmdomains:
> +	if (!core->has_opp_table)
> +		return 0;
> +
> +	/* Attach the power domain for setting performance state */
> +	opp_table = dev_pm_opp_attach_genpd(dev, res->opp_pmdomain, &opp_virt_dev);
> +	if (IS_ERR(opp_table)) {
> +		ret = PTR_ERR(opp_table);
> +		goto opp_attach_err;
> +	}
> +
> +	core->opp_pmdomain = *opp_virt_dev;
> +	core->opp_dl_venus = device_link_add(dev, core->opp_pmdomain,
> +					     DL_FLAG_RPM_ACTIVE |
> +					     DL_FLAG_PM_RUNTIME |
> +					     DL_FLAG_STATELESS);
> +	if (!core->opp_dl_venus) {
> +		ret = -ENODEV;
> +		goto opp_dl_add_err;
> +	}
> +
>  	return 0;
> +
> +opp_dl_add_err:
> +	dev_pm_domain_detach(core->opp_pmdomain, true);
> +opp_attach_err:
> +	if (core->pd_dl_venus) {
> +		device_link_del(core->pd_dl_venus);
> +		for (i = 0; i < res->vcodec_pmdomains_num; i++) {
> +			if (IS_ERR_OR_NULL(core->pmdomains[i]))
> +				continue;
> +			dev_pm_domain_detach(core->pmdomains[i], true);
> +		}
> +	}
> +	return ret;
>  }
>  
>  static void vcodec_domains_put(struct device *dev)
> @@ -773,7 +810,7 @@ static void vcodec_domains_put(struct device *dev)
>  	unsigned int i;
>  
>  	if (!res->vcodec_pmdomains_num)
> -		return;
> +		goto skip_pmdomains;
>  
>  	if (core->pd_dl_venus)
>  		device_link_del(core->pd_dl_venus);
> @@ -783,6 +820,15 @@ static void vcodec_domains_put(struct device *dev)
>  			continue;
>  		dev_pm_domain_detach(core->pmdomains[i], true);
>  	}
> +
> +skip_pmdomains:
> +	if (!res->opp_pmdomain)
> +		return;
> +
> +	if (core->opp_dl_venus)
> +		device_link_del(core->opp_dl_venus);
> +
> +	dev_pm_domain_detach(core->opp_pmdomain, true);

Without corresponding changes in venus DT node we call pm_domain_detach
with core->opp_pmdomain = NULL which triggers NULL pointer dereference.

I guess you should check:

	if (core->has_opp_table)
		dev_pm_domain_detach(core->opp_pmdomain, true);

or

	if (core->opp_pmdomain)
		dev_pm_domain_detach(core->opp_pmdomain, true);


... not sure which one is more appropriate or both are.


-- 
regards,
Stan