linux-kernel - Re: [PATCH 1/2] mailbox: pcc: Add processing platform notification for slave subspaces

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Message-ID: <20230302135201.c2qbvtx6k5mgnobv@bogus>
Date:   Thu, 2 Mar 2023 13:52:01 +0000
From:   Sudeep Holla <sudeep.holla@....com>
To:     "lihuisong (C)" <lihuisong@...wei.com>
Cc:     robbiek@...ghtlabs.com, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org, rafael@...nel.org,
        Sudeep Holla <sudeep.holla@....com>,
        rafael.j.wysocki@...el.com, wanghuiqiang@...wei.com,
        zhangzekun11@...wei.com, wangxiongfeng2@...wei.com,
        tanxiaofei@...wei.com, guohanjun@...wei.com, xiexiuqi@...wei.com,
        wangkefeng.wang@...wei.com, huangdaode@...wei.com
Subject: Re: [PATCH 1/2] mailbox: pcc: Add processing platform notification
 for slave subspaces

On Thu, Mar 02, 2023 at 09:57:35AM +0800, lihuisong (C) wrote:
> 
> 在 2023/3/1 21:24, Sudeep Holla 写道:

[...]

> > 
> > +static bool pcc_mbox_cmd_complete_check(struct pcc_chan_info *pchan)
> > +{
> > +       u64 val;
> > +       int ret;
> > +
> > +       ret = pcc_chan_reg_read(&pchan->cmd_complete, &val);
> > +       if (ret)
> > +               return false;
> > +
> 
> we indeed already check if cmd_complete register is exist.
> IMO, it can simply the code logic and reduce the risk of problems if we
> return true here for the type without this register.
> what do you think?
>

IIUC, your concern is about returning true for type 4 when the register
doesn't exist, right ?

I am saying it won't happen as we bail out if there is no GAS register
from pcc_chan_reg_init(). Or am I missing something here ?

> > +       val &= pchan->cmd_complete.status_mask;
> > +
> > +       /*
> > +        * If this is PCC slave subspace channel, then the command complete
> > +        * bit 0 indicates that Platform is sending a notification and OSPM
> > +        * needs to respond this interrupt to process this command.
> > +        */
> > +       if (pchan->type == ACPI_PCCT_TYPE_EXT_PCC_SLAVE_SUBSPACE)
> > +               return !val;
> > +       else
> > +               return !!val;
> This else branch is not applicable to type 3. type 3 will cannot respond
> interrupt.

Sorry I don't understand what you mean by that.

-- 
Regards,
Sudeep