gx_i2c: bus stuck → Implement i2c recovery (toggle SCL 9 times manually).

// In gx_i2c_xfer(), add recovery if (status & I2C_STAT_BUS_BUSY) gx_i2c_reset(adap); mdelay(1);

writel_relaxed(val, i2c->base + reg);

#define I2C_CON 0x00 #define I2C_TAR 0x04 #define I2C_DATA_CMD 0x10 #define I2C_ENABLE 0x6C static inline void gx_i2c_writel(struct gx_i2c *i2c, u32 val, u32 reg)

Example (display vsync):

static irqreturn_t gx_disp_irq(int irq, void *dev_id)

Manually gate unused clocks via /sys/kernel/debug/clk/clk_summary and write to clk_disable .

gx_disp: failed to set mode → EDID read failed. Force mode via kernel param: video=HDMI-A-1:1920x1080@60 .

GX PM is notoriously minimal : only suspend/resume for system sleep, no runtime PM. Causes high idle power.

echo 0x1f > /sys/module/gx_vpu/parameters/debug to enable verbose logging. Check cat /proc/interrupts | grep vpu for interrupt count. 4.4 I2C / SPI Drivers ( gx_i2c , gx_spi ) These are simple wrapper drivers around DesignWare IP or a custom bit-bang. The GX implementation often lacks proper clock gating or recovery on bus hang.

Userspace (GStreamer V4L2) → ioctl(VIDIOC_QBUF) → driver copies bitstream to SRAM/CMA → triggers VPU via mailbox → VPU interrupts on frame done → driver queues decoded frame to capture buffer.

VPU_REG_DEC_CTRL (0xF100_0000) VPU_REG_STATUS (0xF100_0004) // bit 0 = busy VPU_REG_DATA (0xF100_0008) // firmware mailbox Driver requests gx_vpu_fw.bin from /lib/firmware . Missing firmware → VPU fails to start.