linux-kernel - Re: [PATCH v7 3/3] soc: qcom: rpmh: Invoke rpmh

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Date:   Wed, 26 Feb 2020 14:49:43 -0800
From:   Stephen Boyd <swboyd@...omium.org>
To:     Maulik Shah <mkshah@...eaurora.org>, bjorn.andersson@...aro.org,
        evgreen@...omium.org, mka@...omium.org
Cc:     linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        agross@...nel.org, dianders@...omium.org, rnayak@...eaurora.org,
        ilina@...eaurora.org, lsrao@...eaurora.org,
        Maulik Shah <mkshah@...eaurora.org>
Subject: Re: [PATCH v7 3/3] soc: qcom: rpmh: Invoke rpmh_flush for dirty caches

Quoting Maulik Shah (2020-02-25 21:27:13)
> Add changes to invoke rpmh flush when the data in cache is dirty.
> 
> This is done only if OSI is not supported in PSCI. If OSI is supported
> rpmh_flush can get invoked when the last cpu going to power collapse

Please write rpmh_flush() so we know it's a function and not a variable.

> deepest low power mode.
> 
> Signed-off-by: Maulik Shah <mkshah@...eaurora.org>
> Reviewed-by: Srinivas Rao L <lsrao@...eaurora.org>
> ---
>  drivers/soc/qcom/rpmh.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/soc/qcom/rpmh.c b/drivers/soc/qcom/rpmh.c
> index 83ba4e0..839af8d 100644
> --- a/drivers/soc/qcom/rpmh.c
> +++ b/drivers/soc/qcom/rpmh.c
> @@ -12,6 +12,7 @@
>  #include <linux/module.h>
>  #include <linux/of.h>
>  #include <linux/platform_device.h>
> +#include <linux/psci.h>
>  #include <linux/slab.h>
>  #include <linux/spinlock.h>
>  #include <linux/types.h>
> @@ -163,6 +164,9 @@ static struct cache_req *cache_rpm_request(struct rpmh_ctrlr *ctrlr,
>  unlock:
>         spin_unlock_irqrestore(&ctrlr->cache_lock, flags);
>  
> +       if (ctrlr->dirty && !psci_has_osi_support())

Can we introduce a stub function for psci_has_osi_support() when
CONFIG_ARM_PSCI_FW=n? This driver currently has:

  config QCOM_RPMH
        bool "Qualcomm RPM-Hardened (RPMH) Communication"
	depends on ARCH_QCOM && ARM64 || COMPILE_TEST


which implies that this will break build testing once built on something
that isn't arm64.


> +               return rpmh_flush(ctrlr) ? ERR_PTR(-EINVAL) : req;
> +
>         return req;
>  }
>  
> @@ -391,6 +395,8 @@ int rpmh_write_batch(const struct device *dev, enum rpmh_state state,
>  
>         if (state != RPMH_ACTIVE_ONLY_STATE) {
>                 cache_batch(ctrlr, req);
> +               if (!psci_has_osi_support())
> +                       return rpmh_flush(ctrlr);

While the diff is small it is also sad that we turn around after adding
it to a list and immediately take it off the list and send it. Can't we
do this without having to do the list add/remove dance?

>                 return 0;
>         }
>