media: staging/ipu7: avoid division by 64-bit value

From: Arnd Bergmann <[email protected]>

On 32-bit targets, this causes a link failure:

x86_64-linux-ld: drivers/staging/media/ipu7/ipu7-isys-csi-phy.o: in function `ipu7_isys_phy_config':
ipu7-isys-csi-phy.c:(.text+0x1509): undefined reference to `__udivdi3'

Note that this does not divide a 64-bit number by a 32-bit one as usual, but the other way round, which is something that the compiler should really be able to figure out but does not (as of gcc-15).

A few lines higher, a similar division is done using the incorrect div_u64() that truncates the 64-bit divisor to 32 bits.

Change both to use the safe but slow div64_u64() helper.

Fixes a516d36bdc3d ("media: staging/ipu7: add IPU7 input system device driver")

Signed-off-by Arnd Bergmann <[email protected]>

---
 drivers/staging/media/ipu7/ipu7-isys-csi-phy.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

drivers/staging/media/ipu7/ipu7-isys-csi-phy.c +3 -2

index 4407750c7f40..b8c5db7ae300 100644
@@ -734,6 +734,7 @@ static void ipu7_isys_cphy_config(struct ipu7_isys *isys, u8 id, u8 lanes,
 	u16 reg;
 	u16 val;
 	u32 i;
+	u64 r64;
 	u32 r;
 
 	if (is_ipu7p5(isys->adev->isp->hw_ver))

@@ -806,8 +807,8 @@ static void ipu7_isys_cphy_config(struct ipu7_isys *isys, u8 id, u8 lanes,
 		dwc_phy_write_mask(isys, id, reg, 2, 0, 2);
 	}
 
-	deass_thresh = (u16)div_u64_rem(7 * 1000 * 6, mbps * 5U, &r) + 1;
-	if (r != 0)
+	deass_thresh = (u16)div64_u64_rem(7 * 1000 * 6, mbps * 5U, &r64) + 1;
+	if (r64 != 0)
 		deass_thresh++;
 
 	reg = CORE_DIG_RW_TRIO0_2;

From: Arnd Bergmann <[email protected]>

On 32-bit targets, this causes a link failure:

x86_64-linux-ld: drivers/staging/media/ipu7/ipu7-isys-csi-phy.o: in function `ipu7_isys_phy_config':
ipu7-isys-csi-phy.c:(.text+0x1509): undefined reference to `__udivdi3'

Note that this does not divide a 64-bit number by a 32-bit one as usual, but the other way round, which is something that the compiler should really be able to figure out but does not (as of gcc-15).

A few lines higher, a similar division is done using the incorrect div_u64() that truncates the 64-bit divisor to 32 bits.

Change both to use the safe but slow div64_u64() helper.

Fixes a516d36bdc3d ("media: staging/ipu7: add IPU7 input system device driver")

Signed-off-by Arnd Bergmann <[email protected]>

---
 drivers/staging/media/ipu7/ipu7-isys-csi-phy.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

drivers/staging/media/ipu7/ipu7-isys-csi-phy.c +1 -0

index 4407750c7f40..b8c5db7ae300 100644
@@ -734,6 +734,7 @@ static void ipu7_isys_cphy_config(struct ipu7_isys *isys, u8 id, u8 lanes,
 	u16 reg;
 	u16 val;
 	u32 i;
+	u64 r64;
 	u32 r;
 
 	if (is_ipu7p5(isys->adev->isp->hw_ver))

drivers/staging/media/ipu7/ipu7-isys-csi-phy.c +0 -0

 	if (delay_thresh < 1)
 		delay_thresh = 1;

Quoted 35 lines · On Wed, 9 Jul 2025 16:56:56 +0200 Arnd Bergmann <[email protected]> wrote:

From: Arnd Bergmann <[email protected]>

On 32-bit targets, this causes a link failure:

x86_64-linux-ld: drivers/staging/media/ipu7/ipu7-isys-csi-phy.o: in function `ipu7_isys_phy_config':
ipu7-isys-csi-phy.c:(.text+0x1509): undefined reference to `__udivdi3'

Note that this does not divide a 64-bit number by a 32-bit one as usual, but the other way round, which is something that the compiler should really be able to figure out but does not (as of gcc-15).

A few lines higher, a similar division is done using the incorrect div_u64() that truncates the 64-bit divisor to 32 bits.

Change both to use the safe but slow div64_u64() helper.

Fixes a516d36bdc3d ("media: staging/ipu7: add IPU7 input system device driver")

Signed-off-by Arnd Bergmann <[email protected]>

---
 drivers/staging/media/ipu7/ipu7-isys-csi-phy.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

drivers/staging/media/ipu7/ipu7-isys-csi-phy.c +1 -0

index 4407750c7f40..b8c5db7ae300 100644
@@ -734,6 +734,7 @@ static void ipu7_isys_cphy_config(struct ipu7_isys *isys, u8 id, u8 lanes,
 	u16 reg;
 	u16 val;
 	u32 i;
+	u64 r64;
 	u32 r;
 
 	if (is_ipu7p5(isys->adev->isp->hw_ver))

drivers/staging/media/ipu7/ipu7-isys-csi-phy.c static void ipu7_isys_cphy_config(struct ipu7_isys *isys, u8 id, u8 lanes, · line 812

Quoted 8 lines

drivers/staging/media/ipu7/ipu7-isys-csi-phy.c +2 -2

@@ -806,8 +807,8 @@ static void ipu7_isys_cphy_config(struct ipu7_isys *isys, u8 id, u8 lanes,
 		dwc_phy_write_mask(isys, id, reg, 2, 0, 2);
 	}
 
-	deass_thresh = (u16)div_u64_rem(7 * 1000 * 6, mbps * 5U, &r) + 1;
-	if (r != 0)
+	deass_thresh = (u16)div64_u64_rem(7 * 1000 * 6, mbps * 5U, &r64) + 1;
+	if (r64 != 0)
 		deass_thresh++;

While 'mbps' is presumably u64, it can't be big.
So this can just be:

	deass_threas = roundup(7 * 1000 * 6 / 5, (u32)mbps) + 1;

Quoted 6 lines

drivers/staging/media/ipu7/ipu7-isys-csi-phy.c +0 -0

 	reg = CORE_DIG_RW_TRIO0_2;

@@ -815,8 +816,7 @@ static void ipu7_isys_cphy_config(struct ipu7_isys *isys, u8 id, u8 lanes,
 		dwc_phy_write_mask(isys, id, reg + 0x400 * i,
 				   deass_thresh, 0, 7);
 

drivers/staging/media/ipu7/ipu7-isys-csi-phy.c static void ipu7_isys_cphy_config(struct ipu7_isys *isys, u8 id, u8 lanes, · line 819

Quoted 3 lines

drivers/staging/media/ipu7/ipu7-isys-csi-phy.c +1 -2

-	delay_thresh =
-		((224U - (9U * 7U)) * 1000U) / (5U * mbps) - 7U;
+	delay_thresh = div64_u64((224U - (9U * 7U)) * 1000U, 5U * mbps) - 7u;

That one just needs a (u32) cast, although the 5 can be moved.