linux-kernel - Re: [PATCH v3 12/13] ACPI: PCC: Simplify PCC shared memory region handling

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Message-ID: <190e3d07-f2b8-4778-b262-24b5650e897b@amperemail.onmicrosoft.com>
Date: Mon, 17 Mar 2025 19:07:50 -0400
From: Adam Young <admiyo@...eremail.onmicrosoft.com>
To: Sudeep Holla <sudeep.holla@....com>, linux-acpi@...r.kernel.org,
 linux-kernel@...r.kernel.org
Cc: Jassi Brar <jassisinghbrar@...il.com>, Huisong Li <lihuisong@...wei.com>,
 Adam Young <admiyo@...amperecomputing.com>,
 Robbie King <robbiek@...ghtlabs.com>, "Rafael J. Wysocki" <rafael@...nel.org>
Subject: Re: [PATCH v3 12/13] ACPI: PCC: Simplify PCC shared memory region
 handling


On 3/13/25 11:28, Sudeep Holla wrote:
> The PCC driver now handles mapping and unmapping of shared memory
> areas as part of pcc_mbox_{request,free}_channel(). Without these before,
> this ACPI PCC opregion driver did handling of those mappings like several
> other PCC mailbox client drivers.
>
> There were redundant operations, leading to unnecessary code. Maintaining
> the consistency across these driver was harder due to scattered handling
> of shmem.
>
> Just use the mapped shmem and remove all redundant operations from this
> driver.
>
> Cc: "Rafael J. Wysocki" <rafael@...nel.org>
> Signed-off-by: Sudeep Holla <sudeep.holla@....com>
> ---
>   drivers/acpi/acpi_pcc.c | 13 ++-----------
>   1 file changed, 2 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/acpi/acpi_pcc.c b/drivers/acpi/acpi_pcc.c
> index 07a034a53acac1e8307265bcc5572054d34d971f..97064e943768ad9f1704effa13dddbc0876a9452 100644
> --- a/drivers/acpi/acpi_pcc.c
> +++ b/drivers/acpi/acpi_pcc.c
> @@ -31,7 +31,6 @@
>   
>   struct pcc_data {
>   	struct pcc_mbox_chan *pcc_chan;
> -	void __iomem *pcc_comm_addr;
>   	struct completion done;
>   	struct mbox_client cl;
>   	struct acpi_pcc_info ctx;
> @@ -81,14 +80,6 @@ acpi_pcc_address_space_setup(acpi_handle region_handle, u32 function,
>   		ret = AE_SUPPORT;
>   		goto err_free_channel;
>   	}
> -	data->pcc_comm_addr = acpi_os_ioremap(pcc_chan->shmem_base_addr,
> -					      pcc_chan->shmem_size);
> -	if (!data->pcc_comm_addr) {
> -		pr_err("Failed to ioremap PCC comm region mem for %d\n",
> -		       ctx->subspace_id);
> -		ret = AE_NO_MEMORY;
> -		goto err_free_channel;
> -	}
>   
>   	*region_context = data;
>   	return AE_OK;
> @@ -113,7 +104,7 @@ acpi_pcc_address_space_handler(u32 function, acpi_physical_address addr,
>   	reinit_completion(&data->done);
>   
>   	/* Write to Shared Memory */
> -	memcpy_toio(data->pcc_comm_addr, (void *)value, data->ctx.length);
> +	memcpy_toio(data->pcc_chan->shmem, (void *)value, data->ctx.length);
>   
>   	ret = mbox_send_message(data->pcc_chan->mchan, NULL);
>   	if (ret < 0)
> @@ -134,7 +125,7 @@ acpi_pcc_address_space_handler(u32 function, acpi_physical_address addr,
>   
>   	mbox_chan_txdone(data->pcc_chan->mchan, ret);
>   
> -	memcpy_fromio(value, data->pcc_comm_addr, data->ctx.length);
> +	memcpy_fromio(value, data->pcc_chan->shmem, data->ctx.length);
>   
>   	return AE_OK;
>   }
>

tested-by: Adam Young<admiyo@...amperecomputing.com>