linux-kernel - Re: [PATCH 03/13] mailbox: pcc: Refactor all PCC channel information into a structure

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Message-ID: <20210714165434.GC6592@e120937-lin>
Date:   Wed, 14 Jul 2021 17:54:34 +0100
From:   Cristian Marussi <cristian.marussi@....com>
To:     Sudeep Holla <sudeep.holla@....com>
Cc:     linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Jassi Brar <jassisinghbrar@...il.com>
Subject: Re: [PATCH 03/13] mailbox: pcc: Refactor all PCC channel information
 into a structure

On Thu, Jul 08, 2021 at 07:08:41PM +0100, Sudeep Holla wrote:
> Currently all the PCC channel specific information are stored/maintained
> in global individual arrays for each of those information. It is not
> scalable and not clean if we have to stash more channel specific
> information. Couple of reasons to stash more information are to extend
> the support to Type 3/4 PCCT subspace and also to avoid accessing the
> PCCT table entries themselves each time we need the information.
> 
> This patch moves all those PCC channel specific information into a
> separate structure pcc_chan_info.
> 
> Signed-off-by: Sudeep Holla <sudeep.holla@....com>
> ---

Hi Sudeep,

>  drivers/mailbox/pcc.c | 106 +++++++++++++++++++++---------------------
>  1 file changed, 53 insertions(+), 53 deletions(-)
> 
> diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c
> index 23391e224a68..c5f481a615b0 100644
> --- a/drivers/mailbox/pcc.c
> +++ b/drivers/mailbox/pcc.c
> @@ -64,12 +64,20 @@
>  
>  static struct mbox_chan *pcc_mbox_channels;
>  
> -/* Array of cached virtual address for doorbell registers */
> -static void __iomem **pcc_doorbell_vaddr;
> -/* Array of cached virtual address for doorbell ack registers */
> -static void __iomem **pcc_doorbell_ack_vaddr;
> -/* Array of doorbell interrupts */
> -static int *pcc_doorbell_irq;
> +/**
> + * struct pcc_chan_info - PCC channel specific information
> + *
> + * @db_vaddr: cached virtual address for doorbell register
> + * @db_ack_vaddr: cached virtual address for doorbell ack register
> + * @db_irq: doorbell interrupt
> + */
> +struct pcc_chan_info {
> +	void __iomem *db_vaddr;
> +	void __iomem *db_ack_vaddr;
> +	int db_irq;
> +};

Given that this db_irq represents the optional completion interrupt that is
used platform-->OSPM to signal command completions and/or notifications/
delayed_responses and it is mentioned indeed in ACPI 6.4 as "Platform
Interrupt" and also referred in this driver as such somewherelse, is it not
misleading to call it then here "doorbell interrupt" since the "doorbell" in
this context is usually the interrupt that goes the other way around
OSPM-->Platform and is indeed handled by a different set of dedicated Doorbell
registers ? (that are indeed called Doorbell throughout this driver down below
...but I understand this was the nomenclature used also before in this driver)

Thanks,
Cristian