linux-kernel - Re: [PATCH 2/5] firmware_loader: add support to handle FW_UPLOAD_ERR

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Message-ID: <20241120165049.jzsveoms2unxt3m6@4VRSMR2-DT.corp.robot.car>
Date: Wed, 20 Nov 2024 08:50:49 -0800
From: Russ Weight <russ.weight@...ux.dev>
To: Marco Felsch <m.felsch@...gutronix.de>
Cc: Luis Chamberlain <mcgrof@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Kamel Bouhara <kamel.bouhara@...tlin.com>,
	Marco Felsch <kernel@...gutronix.de>,
	Henrik Rydberg <rydberg@...math.org>,
	Danilo Krummrich <dakr@...hat.com>, linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org, linux-input@...r.kernel.org
Subject: Re: [PATCH 2/5] firmware_loader: add support to handle
 FW_UPLOAD_ERR_SKIP

On Tue, Nov 19, 2024 at 11:33:51PM +0100, Marco Felsch wrote:
> It's no error if a driver indicates that the firmware is already
> up-to-date and the update can be skipped.
> 
> Signed-off-by: Marco Felsch <m.felsch@...gutronix.de>
> ---
>  drivers/base/firmware_loader/sysfs_upload.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/base/firmware_loader/sysfs_upload.c b/drivers/base/firmware_loader/sysfs_upload.c
> index b3cbe5b156e3..44f3d8fa5e64 100644
> --- a/drivers/base/firmware_loader/sysfs_upload.c
> +++ b/drivers/base/firmware_loader/sysfs_upload.c
> @@ -174,6 +174,10 @@ static void fw_upload_main(struct work_struct *work)
>  	fw_upload_update_progress(fwlp, FW_UPLOAD_PROG_PREPARING);
>  	ret = fwlp->ops->prepare(fwl, fwlp->data, fwlp->remaining_size);
>  	if (ret != FW_UPLOAD_ERR_NONE) {
> +		if (ret == FW_UPLOAD_ERR_SKIP) {
> +			dev_info(fw_dev, "firmware already up-to-date, skip update\n");
> +			ret = FW_UPLOAD_ERR_NONE;
> +		}

If you change the error-code from FW_UPLOAD_ERR_SKIP to
FW_UPLOAD_ERR_NONE, then the "skip" string provided in the previous
patch will never be seen. There are currently no other instances where
an error code requires special-case modifications to the fw_upload
code and I don't think it is necessary to add it here.

The dev_info() message above can be provided by the device driver
that is using this API.

I think you can either:

(1) allow "skip" to be treated as an error. The update didn't happen...

-or-

(2) The prepare function could detect the situation and set
    a flag in the same device driver. Your write function could
    set *written to the full data size and return without writing
    anything. Your poll_complete handler could also return
    FW_UPLOAD_ERR_NONE. Then you don't need to add FW_UPLOAD_ERR_SKIP
    at all. You would get the info message from the device driver
    and fw_upload would exit without an error.

Thanks,
- Russ

>  		fw_upload_set_error(fwlp, ret);
>  		goto putdev_exit;
>  	}
> 
> -- 
> 2.39.5
>