From: Arnd Bergmann <arnd@arndb.de>
To: Georgi Djakov <georgi.djakov@linaro.org>,
Rob Clark <robdclark@chromium.org>,
Kalyan Thota <kalyan_t@codeaurora.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
Matthias Kaehlcke <mka@chromium.org>,
Sibi Sankar <sibis@codeaurora.org>,
Viresh Kumar <viresh.kumar@linaro.org>,
Evan Green <evgreen@chromium.org>,
Akash Asthana <akashast@codeaurora.org>,
linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] drm/msm/dpu: avoid open-coded 64-bit division
Date: Wed, 27 May 2020 15:35:38 +0200 [thread overview]
Message-ID: <20200527133543.599948-1-arnd@arndb.de> (raw)
64-bit integer division is normally not allowed in the kernel
because of the large overhead on 32-bit machines:
drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.o: in function `_dpu_core_perf_crtc_update_bus':
dpu_core_perf.c:(.text+0x810): undefined reference to `__aeabi_uldivmod'
The function already contains a call to do_div(), so I assume this
is never called in a performance critical context, and we can
use div_u64 for the second one as well.
Fixes: 04d9044f6c57 ("drm/msm/dpu: add support for clk and bw scaling for display")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
include/linux/interconnect.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/interconnect.h b/include/linux/interconnect.h
index 3a63d98613fc..8279fe9b2082 100644
--- a/include/linux/interconnect.h
+++ b/include/linux/interconnect.h
@@ -11,7 +11,7 @@
#include <linux/types.h>
/* macros for converting to icc units */
-#define Bps_to_icc(x) ((x) / 1000)
+#define Bps_to_icc(x) div_u64((x), 1000)
#define kBps_to_icc(x) (x)
#define MBps_to_icc(x) ((x) * 1000)
#define GBps_to_icc(x) ((x) * 1000 * 1000)
--
2.26.2
next reply other threads:[~2020-05-27 13:35 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-27 13:35 Arnd Bergmann [this message]
2020-05-27 14:25 ` [PATCH] drm/msm/dpu: avoid open-coded 64-bit division Georgi Djakov
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