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media: platform: raspberrypi: rp1_cfe: Add more debug registers #7338

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Merged
njhollinghurst merged 1 commit into from
May 6, 2026
Merged

media: platform: raspberrypi: rp1_cfe: Add more debug registers #7338

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2 changes: 1 addition & 1 deletion drivers/media/platform/raspberrypi/rp1_cfe/csi2.c
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Original file line number Diff line number Diff line change
Expand Up @@ -574,7 +574,7 @@ int csi2_init(struct csi2_device *csi2, struct dentry *debugfs)
spin_lock_init(&csi2->errors_lock);

csi2->dphy.dev = csi2->v4l2_dev->dev;
dphy_probe(&csi2->dphy);
dphy_probe(&csi2->dphy, debugfs);

debugfs_create_file("csi2_regs", 0444, debugfs, csi2, &csi2_regs_fops);

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46 changes: 43 additions & 3 deletions drivers/media/platform/raspberrypi/rp1_cfe/dphy.c
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Expand Up @@ -16,7 +16,7 @@
#define dphy_info(fmt, arg...) dev_info(dphy->dev, fmt, ##arg)
#define dphy_err(fmt, arg...) dev_err(dphy->dev, fmt, ##arg)

/* DW dphy Host registers */
/* DW CSI-2 Host registers */
#define VERSION 0x000
#define N_LANES 0x004
#define RESETN 0x008
Expand All @@ -29,7 +29,14 @@
#define PHY2_TST_CTRL0 0x058
#define PHY2_TST_CTRL1 0x05c

/* DW dphy Host Transactions */
/* DW CSI-2 Host and PHY debug registers */
#define INT_ST_PHY_FATAL 0x0e0
#define INT_ST_PKT_FATAL 0x0f0
#define INT_ST_FRAME_FATAL 0x100
#define INT_ST_PHY 0x110
#define INT_ST_PKT 0x120

/* DW D-PHY transaction codes */
#define DPHY_HS_RX_CTRL_LANE0_OFFSET 0x44
#define DPHY_PLL_INPUT_DIV_OFFSET 0x17
#define DPHY_PLL_LOOP_DIV_OFFSET 0x18
Expand Down Expand Up @@ -183,7 +190,37 @@ void dphy_stop(struct dphy_data *dphy)
*/
}

void dphy_probe(struct dphy_data *dphy)
static int dphy_debug_show(struct seq_file *s, void *data)
{
/*
* Here we expose various error flags in the CSI-2 Host and PHY.
* All these registers apart from PHY_STOPSTATE are read-to-clear.
* The only reliable way to count errors would be to service a
* dedicated interrupt. For now, we'll just read (and clear) them.
*/
struct dphy_data *dphy = s->private;
int ret;

ret = pm_runtime_resume_and_get(dphy->dev);
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@6by9 6by9 Apr 27, 2026

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I might question whether it is better to use pm_runtime_get_if_in_use so that if the hardware isn't powered up you get told that rather than just getting the hardware defaults.

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@njhollinghurst njhollinghurst Apr 27, 2026

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Quite possibly. I copied and pasted similar code from pisp_fe.c.

BTW I did also wonder about using debugfs_create_regset32() instead; but it wasn't clear how that might interact with the read-to-clear registers. Not sure what if anything it does for power management.

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@6by9 6by9 Apr 27, 2026

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I've just found the same in csi2.c as well. All might benefit from it, assuming that pm_runtime counting is actually correct.

Using regset only really gives a benefit if already using regset, and the CFE driver isn't.

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@njhollinghurst njhollinghurst May 5, 2026

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It's unclear whether or not those registers retain useful debug information about the previous session, while the CFE driver is not in use. However, I'm fairly sure the ISP-FE and CSI2AXI ones do, and we might still benefit from being able to read them. I will do some tests to check this...

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@njhollinghurst njhollinghurst May 5, 2026 •
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Yes, those sticky flags do persist between sessions.

We don't strictly seem to need pm_runtime_resume_and_get() here either (as we're not doing any PHY config bus transactions, and no other part of the MIPI block is getting de-clocked or powered down), but it feels safer to leave it in for now.

if (ret)
return ret;

#define DUMP(reg) seq_printf(s, #reg " \t0x%08x\n", dw_csi2_host_read(dphy, reg))
DUMP(PHY_STOPSTATE); /* Data lane (bits 0-3) or clock (bit 16) is in stopstate */
DUMP(INT_ST_PHY_FATAL); /* HS start sync error for each data lane (bits 0-3) */
DUMP(INT_ST_PKT_FATAL); /* CRC error on VC (bits 0-3); ECC unrecoverable error (bit 16) */
DUMP(INT_ST_FRAME_FATAL); /* FS/FE mismatch (bits 0-3), seq (8-11), CRC error (16-19) */
DUMP(INT_ST_PHY); /* Non-fatal error for each data lane HS (bits 0-3), LP (16-19) */
DUMP(INT_ST_PKT); /* Unknown DT on VC (bits 0-3); ECC corrected error (b16-19) */
#undef DUMP

pm_runtime_put(dphy->dev);
return 0;
}

DEFINE_SHOW_ATTRIBUTE(dphy_debug);

void dphy_probe(struct dphy_data *dphy, struct dentry *debugfs)
{
u32 host_ver;
u8 host_ver_major, host_ver_minor;
Expand All @@ -195,4 +232,7 @@ void dphy_probe(struct dphy_data *dphy)
host_ver_minor += (u8)((host_ver >> 8) - '0');

dphy_info("DW dphy Host HW v%u.%u\n", host_ver_major, host_ver_minor);

if (debugfs)
debugfs_create_file("dphy_debug", 0444, debugfs, dphy, &dphy_debug_fops);
}
3 changes: 2 additions & 1 deletion drivers/media/platform/raspberrypi/rp1_cfe/dphy.h
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Expand Up @@ -7,6 +7,7 @@
#ifndef _RP1_DPHY_
#define _RP1_DPHY_

#include <linux/debugfs.h>
#include <linux/io.h>
#include <linux/types.h>
#include <media/v4l2-mediabus.h>
Expand All @@ -22,7 +23,7 @@ struct dphy_data {
bool lane_polarities[1 + V4L2_MBUS_CSI2_MAX_DATA_LANES];
};

void dphy_probe(struct dphy_data *dphy);
void dphy_probe(struct dphy_data *dphy, struct dentry *debugfs);
void dphy_start(struct dphy_data *dphy);
void dphy_stop(struct dphy_data *dphy);

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4 changes: 4 additions & 0 deletions drivers/media/platform/raspberrypi/rp1_cfe/pisp_fe.c
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Expand Up @@ -24,6 +24,8 @@
#define FE_OUTPUT_STATUS 0x014
#define FE_INT_EN 0x018
#define FE_INT_STATUS 0x01c
#define FE_DEBUG_FIFO_FULLNESS 0x024
#define FE_DEBUG_STATUS2 0x02c

/* CONTROL */
#define FE_CONTROL_QUEUE BIT(0)
Expand Down Expand Up @@ -162,6 +164,8 @@ static int pisp_regs_show(struct seq_file *s, void *data)
DUMP(FE_OUTPUT_STATUS);
DUMP(FE_INT_EN);
DUMP(FE_INT_STATUS);
DUMP(FE_DEBUG_FIFO_FULLNESS);
DUMP(FE_DEBUG_STATUS2);
#undef DUMP

pm_runtime_put(fe->v4l2_dev->dev);
Expand Down
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