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I'll just apply Arnd's patch. If the display team wants to adjust it later to clarify the operation, they should go ahead as a follow up patch.
Thanks,
Alex
From: Abramov, Slava
Sent: Tuesday, July 9, 2019 12:31 PM To: Arnd Bergmann; Wentland, Harry; Li, Sun peng (Leo); Deucher, Alexander; Koenig, Christian; Zhou, David(ChunMing); David Airlie; Daniel Vetter Cc: Liu, Charlene; Park, Chris; Cheng, Tony; Francis, David; linux-kernel@xxxxxxxxxxxxxxx; amd-gfx@xxxxxxxxxxxxxxxxxxxxx; Cornij, Nikola; Laktyushkin, Dmytro; dri-devel@xxxxxxxxxxxxxxxxxxxxx; Lei, Jun; Lakha, Bhawanpreet; Koo, Anthony Subject: Re: [PATCH] drm/amd/display: avoid 64-bit division Hi Arnd!
Thanks for bisecting this issue.
I wonder whether you are going to commit your patch or planning to update it and it's still in your work queue. We have one of our 32-bit builds failing because of this issue, so that I would like either to fix it or wait to your fix if it has chances to go upstream today.
Sincerely,
Slava Abramov From: amd-gfx <amd-gfx-bounces@xxxxxxxxxxxxxxxxxxxxx> on behalf of Arnd Bergmann <arnd@xxxxxxxx>
Sent: Monday, July 8, 2019 9:52:08 AM To: Wentland, Harry; Li, Sun peng (Leo); Deucher, Alexander; Koenig, Christian; Zhou, David(ChunMing); David Airlie; Daniel Vetter Cc: Liu, Charlene; Park, Chris; Arnd Bergmann; Cheng, Tony; Francis, David; linux-kernel@xxxxxxxxxxxxxxx; amd-gfx@xxxxxxxxxxxxxxxxxxxxx; Cornij, Nikola; Laktyushkin, Dmytro; dri-devel@xxxxxxxxxxxxxxxxxxxxx; Lei, Jun; Lakha, Bhawanpreet; Koo, Anthony Subject: [PATCH] drm/amd/display: avoid 64-bit division On 32-bit architectures, dividing a 64-bit integer in the kernel
leads to a link error: ERROR: "__udivdi3" [drivers/gpu/drm/amd/amdgpu/amdgpu.ko] undefined! ERROR: "__divdi3" [drivers/gpu/drm/amd/amdgpu/amdgpu.ko] undefined! Change the two recently introduced instances to a multiply+shift operation that is also much cheaper on 32-bit architectures. We can do that here, since both of them are really 32-bit numbers that change a few percent. Fixes: bedbbe6af4be ("drm/amd/display: Move link functions from dc to dc_link") Fixes: f18bc4e53ad6 ("drm/amd/display: update calculated bounding box logic for NV") Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> --- drivers/gpu/drm/amd/display/dc/core/dc_link.c | 4 ++-- drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c | 2 +- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link.c b/drivers/gpu/drm/amd/display/dc/core/dc_link.c index c17db5c144aa..8dbf759eba45 100644 --- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c +++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c @@ -3072,8 +3072,8 @@ uint32_t dc_link_bandwidth_kbps( * but the difference is minimal and is in a safe direction, * which all works well around potential ambiguity of DP 1.4a spec. */ - long long fec_link_bw_kbps = link_bw_kbps * 970LL; - link_bw_kbps = (uint32_t)(fec_link_bw_kbps / 1000LL); + link_bw_kbps = mul_u64_u32_shr(BIT_ULL(32) * 970LL / 1000, + link_bw_kbps, 32); } #endif diff --git a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c index b35327bafbc5..70ac8a95d2db 100644 --- a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c +++ b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c @@ -2657,7 +2657,7 @@ static void update_bounding_box(struct dc *dc, struct _vcs_dpi_soc_bounding_box_ calculated_states[i].dram_speed_mts = uclk_states[i] * 16 / 1000; // FCLK:UCLK ratio is 1.08 - min_fclk_required_by_uclk = ((unsigned long long)uclk_states[i]) * 1080 / 1000000; + min_fclk_required_by_uclk = mul_u64_u32_shr(BIT_ULL(32) * 1080 / 1000000, uclk_states[i], 32); calculated_states[i].fabricclk_mhz = (min_fclk_required_by_uclk < min_dcfclk) ? min_dcfclk : min_fclk_required_by_uclk; -- 2.20.0 _______________________________________________ amd-gfx mailing list amd-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/amd-gfx |
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