linux-kernel - Re: [PATCH] drm/panthor: clean up some types in panthor_sched

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Date: Mon, 8 Apr 2024 13:27:17 +0100
From: Steven Price <steven.price@....com>
To: Dan Carpenter <dan.carpenter@...aro.org>,
 Boris Brezillon <boris.brezillon@...labora.com>
Cc: Liviu Dudau <liviu.dudau@....com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
 kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] drm/panthor: clean up some types in
 panthor_sched_suspend()

On 08/04/2024 08:36, Dan Carpenter wrote:
> These variables should be u32 instead of u64 because they're only
> storing u32 values.  Also static checkers complain when we do:
> 
> 	suspended_slots &= ~upd_ctx.timedout_mask;
> 
> In this code "suspended_slots" is a u64 and "upd_ctx.timedout_mask".  The
> mask clears out the top 32 bits which would likely be a bug if anything
> were stored there.
> 
> Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>

Reviewed-by: Steven Price <steven.price@....com>

If you fancy a bit more clean-up then I think faulty_slots is completely
redundant as a separate variable. In particular in the "if
(suspended_slots)" section it's updated but that updated value is never
used... otherwise I'll put it on my list for cleaning up later.

> ---
>  drivers/gpu/drm/panthor/panthor_sched.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/panthor/panthor_sched.c b/drivers/gpu/drm/panthor/panthor_sched.c
> index d4bc652b34d5..b3a51a6de523 100644
> --- a/drivers/gpu/drm/panthor/panthor_sched.c
> +++ b/drivers/gpu/drm/panthor/panthor_sched.c
> @@ -2546,7 +2546,7 @@ void panthor_sched_suspend(struct panthor_device *ptdev)
>  {
>  	struct panthor_scheduler *sched = ptdev->scheduler;
>  	struct panthor_csg_slots_upd_ctx upd_ctx;
> -	u64 suspended_slots, faulty_slots;
> +	u32 suspended_slots, faulty_slots;
>  	struct panthor_group *group;
>  	u32 i;
>