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Candidate fixes for camera sync issues #6863

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Candidate fixes for camera sync issues #6863

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c8c70b6
media/platform/raspberypi/rp1_cfe: Candidate fix for #5821
njhollinghurst May 19, 2025
f1b9630
media: i2c: imx477: Disable temperature sensor when enabling XVS
njhollinghurst May 20, 2025
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17 changes: 15 additions & 2 deletions drivers/media/i2c/imx477.c
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Original file line number Diff line number Diff line change
Expand Up @@ -112,6 +112,9 @@ MODULE_PARM_DESC(trigger_mode, "Set vsync trigger mode: 1=source, 2=sink");
#define IMX477_REG_XVS_IO_CTRL 0x3040
#define IMX477_REG_EXTOUT_EN 0x4b81

/* Temperature sensor */
#define IMX477_REG_TEMP_SEN_CTL 0x0138
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As you've defined this, it'd be nice to use that define in mode_common_regs so all instances of 0x0138 are by name.


/* Embedded metadata stream structure */
#define IMX477_EMBEDDED_LINE_WIDTH 16384
#define IMX477_NUM_EMBEDDED_LINES 1
Expand Down Expand Up @@ -1833,6 +1836,9 @@ static int imx477_start_streaming(struct imx477 *imx477)

/* Set vsync trigger mode: 0=standalone, 1=source, 2=sink */
tm = (imx477->trigger_mode_of >= 0) ? imx477->trigger_mode_of : trigger_mode;
if (tm == 1)
imx477_write_reg(imx477, IMX477_REG_TEMP_SEN_CTL,
IMX477_REG_VALUE_08BIT, 0);
imx477_write_reg(imx477, IMX477_REG_MC_MODE,
IMX477_REG_VALUE_08BIT, (tm > 0) ? 1 : 0);
imx477_write_reg(imx477, IMX477_REG_MS_SEL,
Expand All @@ -1843,8 +1849,15 @@ static int imx477_start_streaming(struct imx477 *imx477)
IMX477_REG_VALUE_08BIT, (tm == 1) ? 1 : 0);

/* set stream on register */
return imx477_write_reg(imx477, IMX477_REG_MODE_SELECT,
IMX477_REG_VALUE_08BIT, IMX477_MODE_STREAMING);
ret = imx477_write_reg(imx477, IMX477_REG_MODE_SELECT,
IMX477_REG_VALUE_08BIT, IMX477_MODE_STREAMING);

/* now it's safe to re-enable temp sensor without glitching XVS */
if (tm == 1)
imx477_write_reg(imx477, IMX477_REG_TEMP_SEN_CTL,
IMX477_REG_VALUE_08BIT, 1);

return ret;
}

/* Stop streaming */
Expand Down
16 changes: 13 additions & 3 deletions drivers/media/platform/raspberrypi/rp1_cfe/dphy.c
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Original file line number Diff line number Diff line change
Expand Up @@ -149,6 +149,7 @@ static void dphy_init(struct dphy_data *dphy)

void dphy_start(struct dphy_data *dphy)
{
dw_csi2_host_write(dphy, RESETN, 0);
dw_csi2_host_write(dphy, N_LANES, (dphy->active_lanes - 1));
dphy_init(dphy);
dw_csi2_host_write(dphy, RESETN, 0xffffffff);
Expand All @@ -157,9 +158,18 @@ void dphy_start(struct dphy_data *dphy)

void dphy_stop(struct dphy_data *dphy)
{
/* Set only one lane (lane 0) as active (ON) */
dw_csi2_host_write(dphy, N_LANES, 0);
dw_csi2_host_write(dphy, RESETN, 0);
/*
* We no longer go into reset here, because the camera might still be
* streaming. If we kill the CSI-2 Host in mid-packet, it can leave the
* IDI interface in a bad state, causing the next packet to be lost.
*
* XXX Is it safe to assume it will be idle before the next dphy_start?
* XXX What happens if the camera itself generates an incomplete packet?
*
* TODO: Instead, should we consider resetting the *entire* MIPI block
* (including CSI2AXI and ISP-FE)? That can't safely be done until
* all AXI traffic has completed. It would cause APB access to hang.
*/
}

void dphy_probe(struct dphy_data *dphy)
Expand Down