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SubjectRe: [PATCH] drm: mali-dp: use div_u64 for expensive 64-bit divisions
On Tue, Apr 25, 2017 at 09:56:53PM +0200, Arnd Bergmann wrote:
> On 32-bit machines, we can't divide 64-bit integers:
>
> drivers/gpu/drm/arm/malidp_crtc.o: In function `malidp_crtc_atomic_check':
> malidp_crtc.c:(.text.malidp_crtc_atomic_check+0x3c0): undefined reference to `__aeabi_uldivmod'
> malidp_crtc.c:(.text.malidp_crtc_atomic_check+0x3dc): undefined reference to `__aeabi_uldivmod'
>
> This calls the div_u64 function explicitly instead.
>
> Fixes: 4cea4e9f6690 ("drm: mali-dp: Add plane upscaling support")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Acked-by: Liviu Dudau <liviu.dudau@arm.com>

I'll push the patch to the mali-dp repository. Dave A., if you have pulled the mali-dp
patches then this will need to go in as well, otherwise I will send an updated pull
request soon.

Best regards,
Liviu

> ---
> drivers/gpu/drm/arm/malidp_crtc.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/arm/malidp_crtc.c b/drivers/gpu/drm/arm/malidp_crtc.c
> index 19f1f3b34691..9446a673d469 100644
> --- a/drivers/gpu/drm/arm/malidp_crtc.c
> +++ b/drivers/gpu/drm/arm/malidp_crtc.c
> @@ -266,7 +266,6 @@ static int malidp_crtc_atomic_check_scaling(struct drm_crtc *crtc,
>
> drm_atomic_crtc_state_for_each_plane_state(plane, pstate, state) {
> struct malidp_plane *mp = to_malidp_plane(plane);
> - u64 crtc_w, crtc_h;
> u32 phase;
>
> if (!(mp->layer->id & scaling))
> @@ -276,10 +275,10 @@ static int malidp_crtc_atomic_check_scaling(struct drm_crtc *crtc,
> * Convert crtc_[w|h] to U32.32, then divide by U16.16 src_[w|h]
> * to get the U16.16 result.
> */
> - crtc_w = (u64)pstate->crtc_w << 32;
> - crtc_h = (u64)pstate->crtc_h << 32;
> - h_upscale_factor = (u32)(crtc_w / pstate->src_w);
> - v_upscale_factor = (u32)(crtc_h / pstate->src_h);
> + h_upscale_factor = div_u64((u64)pstate->crtc_w << 32,
> + pstate->src_w);
> + v_upscale_factor = div_u64((u64)pstate->crtc_h << 32,
> + pstate->src_h);
>
> s->enhancer_enable = ((h_upscale_factor >> 16) >= 2 ||
> (v_upscale_factor >> 16) >= 2);
> --
> 2.9.0
>

--
====================
| I would like to |
| fix the world, |
| but they're not |
| giving me the |
\ source code! /
---------------
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