diff mbox series

drm/amd/display: use div_s64() for 64-bit division

Message ID 20210125114012.2480845-1-arnd@kernel.org
State New
Headers show
Series drm/amd/display: use div_s64() for 64-bit division | expand

Commit Message

Arnd Bergmann Jan. 25, 2021, 11:39 a.m. UTC
From: Arnd Bergmann <arnd@arndb.de>


The open-coded 64-bit division causes a link error on 32-bit
machines:

ERROR: modpost: "__udivdi3" [drivers/gpu/drm/amd/amdgpu/amdgpu.ko] undefined!
ERROR: modpost: "__divdi3" [drivers/gpu/drm/amd/amdgpu/amdgpu.ko] undefined!

Use the div_s64() to perform the division here. One of them was an
unsigned division originally, but it looks like signed division was
intended, so use that to consistently allow a negative delay.

Fixes: ea7154d8d9fb ("drm/amd/display: Update dcn30_apply_idle_power_optimizations() code")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

---
 drivers/gpu/drm/amd/display/dc/dcn30/dcn30_hwseq.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

-- 
2.29.2

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Comments

Chen, Guchun Jan. 25, 2021, 12:51 p.m. UTC | #1
[AMD Public Use]

Hi Arnd Bergmann,

Thanks for your patch. This link error during compile has been fixed by below commit and been submitted to drm-next branch already.

5da047444e82 drm/amd/display: fix 64-bit division issue on 32-bit OS

Regards,
Guchun

-----Original Message-----
From: amd-gfx <amd-gfx-bounces@lists.freedesktop.org> On Behalf Of Arnd Bergmann

Sent: Monday, January 25, 2021 7:40 PM
To: Wentland, Harry <Harry.Wentland@amd.com>; Li, Sun peng (Leo) <Sunpeng.Li@amd.com>; Deucher, Alexander <Alexander.Deucher@amd.com>; Koenig, Christian <Christian.Koenig@amd.com>; David Airlie <airlied@linux.ie>; Daniel Vetter <daniel@ffwll.ch>; Aberback, Joshua <Joshua.Aberback@amd.com>; Lakha, Bhawanpreet <Bhawanpreet.Lakha@amd.com>; Kazlauskas, Nicholas <Nicholas.Kazlauskas@amd.com>
Cc: Arnd Bergmann <arnd@arndb.de>; Chalmers, Wesley <Wesley.Chalmers@amd.com>; Zhuo, Qingqing <Qingqing.Zhuo@amd.com>; Siqueira, Rodrigo <Rodrigo.Siqueira@amd.com>; linux-kernel@vger.kernel.org; amd-gfx@lists.freedesktop.org; dri-devel@lists.freedesktop.org; Jacky Liao <ziyu.liao@amd.com>; Leung, Martin <Martin.Leung@amd.com>
Subject: [PATCH] drm/amd/display: use div_s64() for 64-bit division

From: Arnd Bergmann <arnd@arndb.de>


The open-coded 64-bit division causes a link error on 32-bit
machines:

ERROR: modpost: "__udivdi3" [drivers/gpu/drm/amd/amdgpu/amdgpu.ko] undefined!
ERROR: modpost: "__divdi3" [drivers/gpu/drm/amd/amdgpu/amdgpu.ko] undefined!

Use the div_s64() to perform the division here. One of them was an unsigned division originally, but it looks like signed division was intended, so use that to consistently allow a negative delay.

Fixes: ea7154d8d9fb ("drm/amd/display: Update dcn30_apply_idle_power_optimizations() code")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

---
 drivers/gpu/drm/amd/display/dc/dcn30/dcn30_hwseq.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_hwseq.c b/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_hwseq.c
index dff83c6a142a..a133e399e76d 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_hwseq.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_hwseq.c
@@ -772,8 +772,8 @@ bool dcn30_apply_idle_power_optimizations(struct dc *dc, bool enable)
 							cursor_cache_enable ? &cursor_attr : NULL)) {
 				unsigned int v_total = stream->adjust.v_total_max ?
 						stream->adjust.v_total_max : stream->timing.v_total;
-				unsigned int refresh_hz = (unsigned long long) stream->timing.pix_clk_100hz *
-						100LL /	(v_total * stream->timing.h_total);
+				unsigned int refresh_hz = div_s64((unsigned long long) stream->timing.pix_clk_100hz *
+						100LL, v_total * stream->timing.h_total);
 
 				/*
 				 * one frame time in microsec:
@@ -800,8 +800,8 @@ bool dcn30_apply_idle_power_optimizations(struct dc *dc, bool enable)
 				unsigned int denom = refresh_hz * 6528;
 				unsigned int stutter_period = dc->current_state->perf_params.stutter_period_us;
 
-				tmr_delay = (((1000000LL + 2 * stutter_period * refresh_hz) *
-						(100LL + dc->debug.mall_additional_timer_percent) + denom - 1) /
+				tmr_delay = div_s64(((1000000LL + 2 * stutter_period * refresh_hz) *
+						(100LL + dc->debug.mall_additional_timer_percent) + denom - 1),
 						denom) - 64LL;
 
 				/* scale should be increased until it fits into 6 bits */ @@ -815,8 +815,8 @@ bool dcn30_apply_idle_power_optimizations(struct dc *dc, bool enable)
 					}
 
 					denom *= 2;
-					tmr_delay = (((1000000LL + 2 * stutter_period * refresh_hz) *
-							(100LL + dc->debug.mall_additional_timer_percent) + denom - 1) /
+					tmr_delay = div_s64(((1000000LL + 2 * stutter_period * refresh_hz) *
+							(100LL + dc->debug.mall_additional_timer_percent) + denom - 1),
 							denom) - 64LL;
 				}
 
--
2.29.2

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Arnd Bergmann Jan. 25, 2021, 1:10 p.m. UTC | #2
On Mon, Jan 25, 2021 at 1:51 PM Chen, Guchun <Guchun.Chen@amd.com> wrote:
>

> [AMD Public Use]

>

> Hi Arnd Bergmann,

>

> Thanks for your patch. This link error during compile has been fixed by below commit and been submitted to drm-next branch already.

>

> 5da047444e82 drm/amd/display: fix 64-bit division issue on 32-bit OS


Ok, thanks. I assume this will make it into linux-next in the coming days then.

     Arnd
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diff mbox series

Patch

diff --git a/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_hwseq.c b/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_hwseq.c
index dff83c6a142a..a133e399e76d 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_hwseq.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_hwseq.c
@@ -772,8 +772,8 @@  bool dcn30_apply_idle_power_optimizations(struct dc *dc, bool enable)
 							cursor_cache_enable ? &cursor_attr : NULL)) {
 				unsigned int v_total = stream->adjust.v_total_max ?
 						stream->adjust.v_total_max : stream->timing.v_total;
-				unsigned int refresh_hz = (unsigned long long) stream->timing.pix_clk_100hz *
-						100LL /	(v_total * stream->timing.h_total);
+				unsigned int refresh_hz = div_s64((unsigned long long) stream->timing.pix_clk_100hz *
+						100LL, v_total * stream->timing.h_total);
 
 				/*
 				 * one frame time in microsec:
@@ -800,8 +800,8 @@  bool dcn30_apply_idle_power_optimizations(struct dc *dc, bool enable)
 				unsigned int denom = refresh_hz * 6528;
 				unsigned int stutter_period = dc->current_state->perf_params.stutter_period_us;
 
-				tmr_delay = (((1000000LL + 2 * stutter_period * refresh_hz) *
-						(100LL + dc->debug.mall_additional_timer_percent) + denom - 1) /
+				tmr_delay = div_s64(((1000000LL + 2 * stutter_period * refresh_hz) *
+						(100LL + dc->debug.mall_additional_timer_percent) + denom - 1),
 						denom) - 64LL;
 
 				/* scale should be increased until it fits into 6 bits */
@@ -815,8 +815,8 @@  bool dcn30_apply_idle_power_optimizations(struct dc *dc, bool enable)
 					}
 
 					denom *= 2;
-					tmr_delay = (((1000000LL + 2 * stutter_period * refresh_hz) *
-							(100LL + dc->debug.mall_additional_timer_percent) + denom - 1) /
+					tmr_delay = div_s64(((1000000LL + 2 * stutter_period * refresh_hz) *
+							(100LL + dc->debug.mall_additional_timer_percent) + denom - 1),
 							denom) - 64LL;
 				}