linux-kernel - Re: [PATCH 2/2] firmware: arm_scmi: Support 'reg-io-width' property for shared memory

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Message-ID: <40d5782e-6b04-40c9-9b44-6960cd61eff1@broadcom.com>
Date: Sun, 11 Aug 2024 14:08:38 -0700
From: Florian Fainelli <florian.fainelli@...adcom.com>
To: linux-arm-kernel@...ts.infradead.org
Cc: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Sudeep Holla <sudeep.holla@....com>,
 Cristian Marussi <cristian.marussi@....com>,
 "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
 <devicetree@...r.kernel.org>, open list <linux-kernel@...r.kernel.org>,
 arm-scmi@...r.kernel.org, james.quinlan@...adcom.com,
 justin.chen@...adcom.com, kapil.hali@...adcom.com,
 bcm-kernel-feedback-list@...adcom.com
Subject: Re: [PATCH 2/2] firmware: arm_scmi: Support 'reg-io-width' property
 for shared memory



On 8/10/2024 2:46 PM, Florian Fainelli wrote:
> Some shared memory areas might only support a certain access width,
> (e.g.: 32 bits accesses only). Update the shmem layer to support
> reading from and writing to such shared memory area using the specified
> I/O width in the Device Tree. The various transport layers making use of
> the shmem.c code are updated accordingly to pass the I/O width to the
> routines that need it.
> 
> Signed-off-by: Florian Fainelli <florian.fainelli@...adcom.com>
> ---
[snip]

> static void shmem_fetch_response(struct scmi_shared_mem __iomem *shmem,
> -				 struct scmi_xfer *xfer)
> +				 struct scmi_xfer *xfer,
> +				 u32 shmem_io_width)
>   {
>   	size_t len = ioread32(&shmem->length);
>   
> @@ -90,20 +144,19 @@ static void shmem_fetch_response(struct scmi_shared_mem __iomem *shmem,
>   	/* Skip the length of header and status in shmem area i.e 8 bytes */
>   	xfer->rx.len = min_t(size_t, xfer->rx.len, len > 8 ? len - 8 : 0);
>   
> -	/* Take a copy to the rx buffer.. */
> -	memcpy_fromio(xfer->rx.buf, shmem->msg_payload + 4, xfer->rx.len);
> +	__shmem_fetch_resp_notif_data(xfer, shmem, shmem_io_width);

As Justin pointed out to me separately, the source pointer is different 
for response and notifications, will fix that, too.
-- 
Florian