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

[lihuisong (C)]

在 2023/3/3 19:07, Sudeep Holla 写道:
> On Fri, Mar 03, 2023 at 09:50:00AM +0800, lihuisong (C) wrote:
> > 在 2023/3/2 21:52, Sudeep Holla 写道:
> > > 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 ?
> > Return true in advance for the type without the cmd_complete register.
> > If support the register, we judge if the channel should respond the
> > interrupt based on the value of cmd_complete, like bellow.
> Right, sorry for missing that.
>
> > -->8
> > +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;
> > +
> > +        if (!pchan->cmd_complete.gas)
> > +                return true;
> > +
> Yes we need the above check.
>
> > +       /*
> > +         * Judge if the channel respond the interrupt based on the value of
> > +         * command complete.
> > +         */
> > +       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;
> > +}
> > > 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 ?
> > Yes, what you say is also ok. Just wondering if it is better to simply the
> > logic.
> Understood now.
>
> > > > > +       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.
> > Sorry for my mistake.
> > I meant that the type2 channel always return false in this function and
> > never respond the interrupt if no check for the GAS register.
> > Because the 'val' for the type without the register is zero.
> Agreed as mentioned above, we need to bail out with true return if no GAS is
> found.
Ok, I will fix it as mentioned above.
> .