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sensor: fix IMX415 latching into an IMX335 misdetection via 0x316A #179

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Merged
widgetii merged 2 commits into from
Jul 30, 2026
Merged

sensor: fix IMX415 latching into an IMX335 misdetection via 0x316A #179

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f429cbe
sensor: fix IMX415 latching into an IMX335 misdetection via 0x316A
widgetii Jul 30, 2026
46b775c
sensor: don't let a failed discriminator read fall back to IMX335
widgetii Jul 30, 2026
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29 changes: 22 additions & 7 deletions src/sensors.c
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Original file line number Diff line number Diff line change
Expand Up @@ -158,10 +158,9 @@ static int detect_sony_sensor(sensor_ctx_t *ctx, int fd,
if (i2c_change_addr(fd, i2c_addr) < 0)
return false;

// 0x3057 is Y_OUT_SIZE MSB (host-writable), not a chip ID — Sony
// sensors have no dedicated chip ID register. IMX335 can read 0x06
// 0x3057 is Y_OUT_SIZE MSB and is host-writable: IMX335 reads 0x06
// here after a WDR-cropping cycle (#157). Disambiguate via OB
// cropping defaults that survive majestic init:
// cropping defaults that survive sensor re-initialisation:
// IMX335: 0x3072=0x28, 0x3074=0xB0
// IMX347: 0x3072=0x14, 0x3074=0x3C
int chip_id = READ(0x57);
Expand Down Expand Up @@ -189,8 +188,24 @@ static int detect_sony_sensor(sensor_ctx_t *ctx, int fd,
if (r316A == -1)
return false;

// HINT: possible check 0x316A == 0x7C && 0x3078 == 0x1
if (r316A > 0 && ((r316A & 0xFC) == 0x7C)) {
// 0x316A is INCKSEL4: IMX415 reads 0x7E here just like IMX335, and
// libsns_imx335.so *writes* 0x316A=0x7E in both its linear and WDR init
// tables. Once an IMX415 has been brought up with the IMX335 driver the
// misdetection latches until the sensor loses power. Rule IMX415 out
// first: 3B00h is "set to 2Eh, reset default 28h" (IMX415 datasheet p.46)
// and 300Bh is a reset default that neither vendor init table touches
// (IMX415: 0xA0, IMX335: 0x00).
int r3B00 = READ(0xB00);
int r300B = READ(0xB);
int is_imx415 = (r3B00 == 0x2E || r3B00 == 0x28) && r300B == 0xA0;

if (r316A > 0 && ((r316A & 0xFC) == 0x7C) && !is_imx415) {
// A failed read (-1) must not pass for "not IMX415": a latched
// IMX415 would slip back into IMX335 here and re-arm the loop.
// Only this decision needs the guard — the checks below re-test
// 0x3B00 on their own.
if (r3B00 == -1 || r300B == -1)
return false;
sprintf(ctx->sensor_id, "IMX335");
return true;
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}
Expand All @@ -208,8 +223,8 @@ static int detect_sony_sensor(sensor_ctx_t *ctx, int fd,

// from IMX415 datasheet, p.46
// 3B00h, Set to "2Eh", default value after reset is 28h
// HINT: possible check 0x300B == 0xA0 && 0x30C0 == 0x20
int r3B00 = READ(0xB00);
// Looser than the is_imx415 test above on purpose: catches an IMX415
// whose 0x300B differs, once 0x316A has ruled IMX335 out.
if (r3B00 == 0x2E || r3B00 == 0x28) {
sprintf(ctx->sensor_id, "IMX415");
return true;
Expand Down