linux-kernel - [PATCH] media: amlogic: c3-mipi-csi2: Handle 64-bits division

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Message-Id: <20250510-amlogic-div64-div-v1-1-e475d4de721f@ideasonboard.com>
Date: Sat, 10 May 2025 10:48:52 +0200
From: Jacopo Mondi <jacopo.mondi@...asonboard.com>
To: Hans Verkuil <hverkuil@...all.nl>, 
 Daniel Scally <dan.scally@...asonboard.com>, Keke Li <keke.li@...ogic.com>, 
 Mauro Carvalho Chehab <mchehab@...nel.org>, 
 Nathan Chancellor <nathan@...nel.org>, 
 Nick Desaulniers <nick.desaulniers+lkml@...il.com>, 
 Bill Wendling <morbo@...gle.com>, Justin Stitt <justinstitt@...gle.com>
Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org, 
 llvm@...ts.linux.dev, kernel test robot <lkp@...el.com>, 
 Jacopo Mondi <jacopo.mondi@...asonboard.com>
Subject: [PATCH] media: amlogic: c3-mipi-csi2: Handle 64-bits division

The kernel test robot reports the following error when building on
Hexagon with hexagon-allmodconfig.

ERROR: modpost: "__hexagon_divdi3"
[drivers/media/platform/amlogic/c3/mipi-csi2/c3-mipi-csi2.ko] undefined!

The error is caused by using DIV_ROUND_UP() with a 64 bits divisor with
a 32-bit dividend, which on Hexagon and clang-17 is resolved with a call
to the __hexagon_divdi3() helper function, part of the compiler support
library and not available when building Linux.

Use DIV_ROUND_UP_ULL() to fix the build error and avoid calling the
__hexagon_divdi3() helper function.

Reported-by: kernel test robot <lkp@...el.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202505101334.UHxNcUUO-lkp@intel.com/
Signed-off-by: Jacopo Mondi <jacopo.mondi@...asonboard.com>
---
Hi Hans,
   this should likely be fast-tracked to land in v6.16 with the Amlogic
C3 ISP support.

Thanks
---
 drivers/media/platform/amlogic/c3/mipi-csi2/c3-mipi-csi2.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/media/platform/amlogic/c3/mipi-csi2/c3-mipi-csi2.c b/drivers/media/platform/amlogic/c3/mipi-csi2/c3-mipi-csi2.c
index f92815ffa4ae..1011ab3ebac7 100644
--- a/drivers/media/platform/amlogic/c3/mipi-csi2/c3-mipi-csi2.c
+++ b/drivers/media/platform/amlogic/c3/mipi-csi2/c3-mipi-csi2.c
@@ -5,6 +5,7 @@
 
 #include <linux/clk.h>
 #include <linux/device.h>
+#include <linux/math.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/platform_device.h>
@@ -321,7 +322,7 @@ static void c3_mipi_csi_cfg_dphy(struct c3_csi_device *csi, s64 rate)
 	u32 settle;
 
 	/* Calculate the high speed settle */
-	val = DIV_ROUND_UP(1000000000, rate);
+	val = DIV_ROUND_UP_ULL(1000000000, rate);
 	settle = (16 * val + 230) / 10;
 
 	c3_mipi_csi_write(csi, MIPI_PHY_CLK_LANE_CTRL,

---
base-commit: 3328eb4dfec23cb3055cda24087cd1cdee925676
change-id: 20250510-amlogic-div64-div-6d0d5a6ec566

Best regards,
-- 
Jacopo Mondi <jacopo.mondi@...asonboard.com>