linux-kernel - Re: [PATCH 08/14] mailbox: pcc: Always map the shared memory communication address

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Message-ID: <fc45c6c7-6828-d36e-3bb1-9f90fec01b45@huawei.com>
Date: Wed, 5 Mar 2025 14:54:39 +0800
From: "lihuisong (C)" <lihuisong@...wei.com>
To: Sudeep Holla <sudeep.holla@....com>, <linux-acpi@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
CC: Jassi Brar <jassisinghbrar@...il.com>, Adam Young
	<admiyo@...amperecomputing.com>
Subject: Re: [PATCH 08/14] mailbox: pcc: Always map the shared memory
 communication address


在 2025/3/3 18:51, Sudeep Holla 写道:
> Currently the shared memory communication address was mapped by the
> mailbox client drivers leading to all sorts of inconsistencies.
>
> It also has resulted in the inconsistent attributes used while mapping
> the shared memory regions.
>
> In order to remove/eliminate any issues, let us ensures the shared
> memory address is always mapped and unmapped when the PCC channels are
> requested and release.
>
> We need to map them as the ACPI PCCT associates these shared memory
> with each channel subspace and may need use the headers in those
> memory to manage the transport.
>
> Since there are no users of pcc_chan_ioremap() and also it is mapped
> by default, we can stop exporting it and make it static function.

If pcc_chan_ioremap is static function, I think we can delete this 
function which just has one line if put this to pcc_mbox_request_channel().

>
> Signed-off-by: Sudeep Holla <sudeep.holla@....com>
> ---
>   drivers/mailbox/pcc.c | 10 +++++++---
>   include/acpi/pcc.h    |  5 -----
>   2 files changed, 7 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c
> index f230e512c29b79fc03e429145180ff049a250d2d..5f2e2b727d99f07c44e87e44c11ba0aefe3a2318 100644
> --- a/drivers/mailbox/pcc.c
> +++ b/drivers/mailbox/pcc.c
> @@ -357,7 +357,7 @@ static irqreturn_t pcc_mbox_irq(int irq, void *p)
>   	return IRQ_HANDLED;
>   }
>   
> -int pcc_mbox_ioremap(struct mbox_chan *chan)
> +static int pcc_mbox_ioremap(struct mbox_chan *chan)
>   {
>   	struct pcc_chan_info *pchan_info;
>   	struct pcc_mbox_chan *pcc_mbox_chan;
> @@ -374,7 +374,6 @@ int pcc_mbox_ioremap(struct mbox_chan *chan)
>   
>   	return 0;
>   }
> -EXPORT_SYMBOL_GPL(pcc_mbox_ioremap);
>   
>   /**
>    * pcc_mbox_request_channel - PCC clients call this function to
> @@ -409,7 +408,12 @@ pcc_mbox_request_channel(struct mbox_client *cl, int subspace_id)
>   	if (rc)
>   		return ERR_PTR(rc);
>   
> -	return &pchan->chan;
> +	rc = pcc_mbox_ioremap(chan);
> +	if (!rc)
> +		return &pchan->chan;
> +
> +	mbox_free_channel(chan);
> +	return ERR_PTR(rc);
>   }
>   EXPORT_SYMBOL_GPL(pcc_mbox_request_channel);
>   
> diff --git a/include/acpi/pcc.h b/include/acpi/pcc.h
> index 699c1a37b8e7846362bae35477eb5736be15d79e..0462bb9da6513a241f3b652b8e203299a1d990c7 100644
> --- a/include/acpi/pcc.h
> +++ b/include/acpi/pcc.h
> @@ -38,7 +38,6 @@ struct pcc_mbox_chan {
>   extern struct pcc_mbox_chan *
>   pcc_mbox_request_channel(struct mbox_client *cl, int subspace_id);
>   extern void pcc_mbox_free_channel(struct pcc_mbox_chan *chan);
> -extern int pcc_mbox_ioremap(struct mbox_chan *chan);
>   #else
>   static inline struct pcc_mbox_chan *
>   pcc_mbox_request_channel(struct mbox_client *cl, int subspace_id)
> @@ -46,10 +45,6 @@ pcc_mbox_request_channel(struct mbox_client *cl, int subspace_id)
>   	return ERR_PTR(-ENODEV);
>   }
>   static inline void pcc_mbox_free_channel(struct pcc_mbox_chan *chan) { }
> -static inline int pcc_mbox_ioremap(struct mbox_chan *chan)
> -{
> -	return 0;
> -};
>   #endif
>   
>   #endif /* _PCC_H */
>