diff mbox series

drm/amd/display: fix 64-bit integer division

Message ID 20210225143339.3693838-1-arnd@kernel.org
State New
Headers show
Series drm/amd/display: fix 64-bit integer division | expand

Commit Message

Arnd Bergmann Feb. 25, 2021, 2:33 p.m. UTC
From: Arnd Bergmann <arnd@arndb.de>


The new display synchronization code caused a regression
on all 32-bit architectures:

ld.lld: error: undefined symbol: __aeabi_uldivmod
>>> referenced by dce_clock_source.c

>>>               gpu/drm/amd/display/dc/dce/dce_clock_source.o:(get_pixel_clk_frequency_100hz) in archive drivers/built-in.a


ld.lld: error: undefined symbol: __aeabi_ldivmod
>>> referenced by dc_resource.c

>>>               gpu/drm/amd/display/dc/core/dc_resource.o:(resource_are_vblanks_synchronizable) in archive drivers/built-in.a

>>> referenced by dc_resource.c

>>>               gpu/drm/amd/display/dc/core/dc_resource.o:(resource_are_vblanks_synchronizable) in archive drivers/built-in.a

>>> referenced by dc_resource.c

>>>               gpu/drm/amd/display/dc/core/dc_resource.o:(resource_are_vblanks_synchronizable) in archive drivers/built-in.a


This is not a fast path, so the use of an explicit div_u64/div_s64
seems appropriate.

Fixes: 77a2b7265f20 ("drm/amd/display: Synchronize displays with different timings")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

---
 drivers/gpu/drm/amd/display/dc/core/dc_resource.c    | 12 ++++++------
 .../gpu/drm/amd/display/dc/dce/dce_clock_source.c    |  6 +++---
 2 files changed, 9 insertions(+), 9 deletions(-)

-- 
2.29.2

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Comments

Arnd Bergmann Feb. 25, 2021, 9:36 p.m. UTC | #1
On Thu, Feb 25, 2021 at 3:33 PM Arnd Bergmann <arnd@kernel.org> wrote:
>

> From: Arnd Bergmann <arnd@arndb.de>

>

> The new display synchronization code caused a regression

> on all 32-bit architectures:

>

> ld.lld: error: undefined symbol: __aeabi_uldivmod

> >>> referenced by dce_clock_source.c

> >>>               gpu/drm/amd/display/dc/dce/dce_clock_source.o:(get_pixel_clk_frequency_100hz) in archive drivers/built-in.a

>

> ld.lld: error: undefined symbol: __aeabi_ldivmod

> >>> referenced by dc_resource.c

> >>>               gpu/drm/amd/display/dc/core/dc_resource.o:(resource_are_vblanks_synchronizable) in archive drivers/built-in.a

> >>> referenced by dc_resource.c

> >>>               gpu/drm/amd/display/dc/core/dc_resource.o:(resource_are_vblanks_synchronizable) in archive drivers/built-in.a

> >>> referenced by dc_resource.c

> >>>               gpu/drm/amd/display/dc/core/dc_resource.o:(resource_are_vblanks_synchronizable) in archive drivers/built-in.a

>

> This is not a fast path, so the use of an explicit div_u64/div_s64

> seems appropriate.


I found two more instances:

>>> referenced by dcn20_optc.c

>>>               gpu/drm/amd/display/dc/dcn20/dcn20_optc.o:(optc2_align_vblanks) in archive drivers/built-in.a


>>> referenced by dcn10_hw_sequencer.c

>>>               gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.o:(reduceSizeAndFraction) in archive drivers/built-in.a


I have patches for both, but will let the randconfig build box keep working
on it over night to see if there are any others. Let me know if you want a
combined patch or one per file once there are no more regressions.

        Arnd
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Stempen, Vladimir Feb. 25, 2021, 9:39 p.m. UTC | #2
[AMD Official Use Only - Internal Distribution Only]

Hi Arnd,
I have all the patches ready and I have tested them with the feature/platform I'm working on and Bindu helped to test the 32bit build.
I'm in process of submitting the latest change.
Thanks,
Vladimir.

On 2021-02-25, 4:36 PM, "Arnd Bergmann" <arnd@kernel.org> wrote:

    On Thu, Feb 25, 2021 at 3:33 PM Arnd Bergmann <arnd@kernel.org> wrote:
    >

    > From: Arnd Bergmann <arnd@arndb.de>

    >

    > The new display synchronization code caused a regression

    > on all 32-bit architectures:

    >

    > ld.lld: error: undefined symbol: __aeabi_uldivmod

    > >>> referenced by dce_clock_source.c

    > >>>               gpu/drm/amd/display/dc/dce/dce_clock_source.o:(get_pixel_clk_frequency_100hz) in archive drivers/built-in.a

    >

    > ld.lld: error: undefined symbol: __aeabi_ldivmod

    > >>> referenced by dc_resource.c

    > >>>               gpu/drm/amd/display/dc/core/dc_resource.o:(resource_are_vblanks_synchronizable) in archive drivers/built-in.a

    > >>> referenced by dc_resource.c

    > >>>               gpu/drm/amd/display/dc/core/dc_resource.o:(resource_are_vblanks_synchronizable) in archive drivers/built-in.a

    > >>> referenced by dc_resource.c

    > >>>               gpu/drm/amd/display/dc/core/dc_resource.o:(resource_are_vblanks_synchronizable) in archive drivers/built-in.a

    >

    > This is not a fast path, so the use of an explicit div_u64/div_s64

    > seems appropriate.


    I found two more instances:

    >>> referenced by dcn20_optc.c

    >>>               gpu/drm/amd/display/dc/dcn20/dcn20_optc.o:(optc2_align_vblanks) in archive drivers/built-in.a


    >>> referenced by dcn10_hw_sequencer.c

    >>>               gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.o:(reduceSizeAndFraction) in archive drivers/built-in.a


    I have patches for both, but will let the randconfig build box keep working
    on it over night to see if there are any others. Let me know if you want a
    combined patch or one per file once there are no more regressions.

            Arnd
diff mbox series

Patch

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_resource.c b/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
index 0241c9d96d7a..49214c59c836 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
@@ -441,15 +441,15 @@  bool resource_are_vblanks_synchronizable(
 		if (stream2->timing.pix_clk_100hz*100/stream2->timing.h_total/
 				stream2->timing.v_total > 60)
 			return false;
-		frame_time_diff = (int64_t)10000 *
+		frame_time_diff = div_s64(10000ll *
 			stream1->timing.h_total *
 			stream1->timing.v_total *
-			stream2->timing.pix_clk_100hz /
-			stream1->timing.pix_clk_100hz /
-			stream2->timing.h_total /
-			stream2->timing.v_total;
+			stream2->timing.pix_clk_100hz,
+			stream1->timing.pix_clk_100hz *
+			stream2->timing.h_total *
+			stream2->timing.v_total);
 		for (i = 0; i < rr_count; i++) {
-			int64_t diff = (frame_time_diff * base60_refresh_rates[i]) / 10 - 10000;
+			int64_t diff = div_s64(frame_time_diff * base60_refresh_rates[i], 10) - 10000;
 
 			if (diff < 0)
 				diff = -diff;
diff --git a/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c b/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c
index 6f47f9bab5ee..85ed6f2c9647 100644
--- a/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c
+++ b/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c
@@ -1013,9 +1013,9 @@  static bool get_pixel_clk_frequency_100hz(
 			 * not be programmed equal to DPREFCLK
 			 */
 			modulo_hz = REG_READ(MODULO[inst]);
-			*pixel_clk_khz = ((uint64_t)clock_hz*
-				clock_source->ctx->dc->clk_mgr->dprefclk_khz*10)/
-				modulo_hz;
+			*pixel_clk_khz = div_u64((uint64_t)clock_hz * 10 *
+				clock_source->ctx->dc->clk_mgr->dprefclk_khz,
+				modulo_hz);
 		} else {
 			/* NOTE: There is agreement with VBIOS here that MODULO is
 			 * programmed equal to DPREFCLK, in which case PHASE will be