From 0b044a999e86ed1aa8791f8bd11a6d7083b33438 Mon Sep 17 00:00:00 2001
From: Arnd Bergmann <arnd@arndb.de>
Date: Mon, 17 Jun 2019 14:51:04 +0200
Subject: [PATCH] drm/komeda: fix 32-bit komeda_crtc_update_clock_ratio
clang points out a bug in the clock calculation on 32-bit, that leads
to the clock_ratio always being zero:
drivers/gpu/drm/arm/display/komeda/komeda_crtc.c:31:36: error: shift count >= width of type [-Werror,-Wshift-count-overflow]
aclk = komeda_calc_aclk(kcrtc_st) << 32;
Move the shift into the division to make it apply on a 64-bit
variable. Also use the more expensive div64_u64() instead of div_u64()
to account for pxlclk being a 64-bit integer.
Fixes: 1f7f9ab7900e ("drm/komeda: Add engine clock requirement check for the downscaling")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: James Qian Wang (Arm Technology China) <james.qian.wang@arm.com>
Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
---
drivers/gpu/drm/arm/display/komeda/komeda_crtc.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c b/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c
index cafb4457e187c..3f222f464eb2f 100644
--- a/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c
+++ b/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c
@@ -28,10 +28,9 @@ static void komeda_crtc_update_clock_ratio(struct komeda_crtc_state *kcrtc_st)
}
pxlclk = kcrtc_st->base.adjusted_mode.clock * 1000;
- aclk = komeda_calc_aclk(kcrtc_st) << 32;
+ aclk = komeda_calc_aclk(kcrtc_st);
- do_div(aclk, pxlclk);
- kcrtc_st->clock_ratio = aclk;
+ kcrtc_st->clock_ratio = div64_u64(aclk << 32, pxlclk);
}
/**
--
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