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Message-ID: <54e4a174-dea7-4588-b8a6-0310c210ffce@arm.com>
Date: Mon, 15 Apr 2024 09:46:58 +0100
From: Steven Price <steven.price@....com>
To: Andy Yan <andyshrk@....com>, boris.brezillon@...labora.com
Cc: daniel@...ll.ch, airlied@...il.com, liviu.dudau@....com,
maarten.lankhorst@...ux.intel.com, tzimmermann@...e.de,
dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
Andy Yan <andy.yan@...k-chips.com>
Subject: Re: [PATCH] drm/panthor: Add defer probe for firmware load
On 13/04/2024 12:49, Andy Yan wrote:
> From: Andy Yan <andy.yan@...k-chips.com>
>
> The firmware in the rootfs will not be accessible until we
> are in the SYSTEM_RUNNING state, so return EPROBE_DEFER until
> that point.
> This let the driver can load firmware when it is builtin.
The usual solution is that the firmware should be placed in the
initrd/initramfs if the module is included there (or built-in). The same
issue was brought up regarding the powervr driver:
https://lore.kernel.org/dri-devel/20240109120604.603700-1-javierm@redhat.com/T/
I'm not sure if that ever actually reached a conclusion though. The
question was deferred to Greg KH but I didn't see Greg actually getting
involved in the thread.
> Signed-off-by: Andy Yan <andy.yan@...k-chips.com>
> ---
>
> drivers/gpu/drm/panthor/panthor_fw.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/panthor/panthor_fw.c b/drivers/gpu/drm/panthor/panthor_fw.c
> index 33c87a59834e..25e375f8333c 100644
> --- a/drivers/gpu/drm/panthor/panthor_fw.c
> +++ b/drivers/gpu/drm/panthor/panthor_fw.c
> @@ -1336,8 +1336,17 @@ int panthor_fw_init(struct panthor_device *ptdev)
> }
>
> ret = panthor_fw_load(ptdev);
> - if (ret)
> + if (ret) {
> + /*
> + * The firmware in the rootfs will not be accessible until we
> + * are in the SYSTEM_RUNNING state, so return EPROBE_DEFER until
> + * that point.
> + */
> + if (system_state < SYSTEM_RUNNING)
This should really only be in the case where ret == -ENOENT - any other
error and the firmware is apparently present but broken in some way, so
there's no point deferring.
I also suspect we'd need some change in panthor_fw_load() to quieten
error messages if we're going to defer on this, in which case it might
make more sense to move this logic into that function.
Steve
> + ret = -EPROBE_DEFER;
> +
> goto err_unplug_fw;
> + }
>
> ret = panthor_vm_active(fw->vm);
> if (ret)
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