linux-kernel - Re: [git pull] drm for 5.7-rc1

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Date:   Thu, 2 Apr 2020 13:43:17 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Nathan Chancellor <natechancellor@...il.com>
Cc:     Dave Airlie <airlied@...il.com>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Chris Wilson <chris@...is-wilson.co.uk>
Subject: Re: [git pull] drm for 5.7-rc1

On Thu, Apr 2, 2020 at 1:33 PM Nathan Chancellor
<natechancellor@...il.com> wrote:
>
> This fixes it but I am not sure if it is proper or not (could be
> problematic if CONFIG_PHYS_ADDR_T_64BIT is set but
> CONFIG_ARCH_DMA_ADDR_T_64BIT is not, not sure if that is possible) so I
> figured I'd report it and let you guys deal with it.

Yeah, no, that patch can't be right.

>From your build failure, your configuration has dma_addr_t being a
'long long unsigned int', and map->offset being a resource_size_t is
for just a 'unsigned int'. Casting 'unsigned int *' to 'unsigned long
long *' is not valid.

You'd have to do something like

        dma_addr_t temp;

and pass the address of *that* in, and then assign that to map->offset
(and verify that it fits), I think.

That's kind of what the old code did.

Or alternatively, the 'offset' field should just be of type
'dma_addr_t' instead (see include/drm/drm_legacy.h). But I didn't
check if something else wants it to be a resource_size_t.

                  Linus