drm/amd/display: Try RGB before YCbCr 4:4:4 in stream validationgrafted

amdgpu_dm_create_validate_stream_for_sink() walks encoding_order[] and
uses the first encoding that validates. YCbCr 4:4:4 is listed before
RGB, so an HDMI sink that advertises 4:4:4 gets YCbCr 4:4:4 whenever the
"color format" property is left at AUTO, even though RGB fits the same
link.

That contradicts the documented AUTO behaviour for HDMI in enum
drm_connector_color_format (RGB, falling back to YCbCr 4:2:0 only when
the bandwidth is not available or the mode is 4:2:0-only), which the
amdgpu implementation of the property also describes. It also leaves
the "Broadcast RGB" property without effect on such sinks, since the
quantization range it selects only applies to RGB output.

Try RGB first. The mask still holds every encoding the sink supports,
so a mode that cannot carry RGB falls back exactly as before.

For reference, v7.2 picked RGB here unless YCbCr 4:4:4 was forced
through debugfs, while earlier kernels picked YCbCr 4:4:4 for any HDMI
sink that advertised it.

Fixes: 0b0ff65d3ca1 ("drm/amd/display: Refactor stream validation")
Suggested-by: Adolfo Rodrigues <adolfotregosa@gmail.com>
Assisted-by: Claude Code:claude-fable-5-1
Signed-off-by: Adrian Betschart <adrian.betschart@cinemaone.ch>
Reviewed-by: Fangzhi Zuo <jerry.zuo@amd.com>
Tested-by: Adolfo Rodrigues <adolfotregosa@gmail.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 7de432bc753133764dc40d37f9388da56de251e7)

2 files changed, 690 insertions, 0 deletions

diff --git a/drivers/gpib/pc2/Makefile b/drivers/gpib/pc2/Makefile
new file mode 100644
index 000000000..481ee4296
--- /dev/null
+++ b/drivers/gpib/pc2/Makefile
@@ -0,0 +1,5 @@
+
+obj-$(CONFIG_GPIB_PC2) += pc2_gpib.o
+
+
+
diff --git a/drivers/gpib/pc2/pc2_gpib.c b/drivers/gpib/pc2/pc2_gpib.c
new file mode 100644
index 000000000..d72601819
--- /dev/null
+++ b/drivers/gpib/pc2/pc2_gpib.c
@@ -0,0 +1,685 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/***************************************************************************
+ *    copyright            : (C) 2001, 2002 by Frank Mori Hess
+ ***************************************************************************/
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#define dev_fmt pr_fmt
+
+#include <linux/ioport.h>
+#include <linux/sched.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/bitops.h>
+#include <asm/dma.h>
+#include <linux/dma-mapping.h>
+#include <linux/string.h>
+#include <linux/init.h>
+#include "nec7210.h"
+#include "gpibP.h"
+
+// struct which defines private_data for pc2 driver
+struct pc2_priv {
+	struct nec7210_priv nec7210_priv;
+	unsigned int irq;
+	// io address that clears interrupt for pc2a (0x2f0 + irq)
+	unsigned int clear_intr_addr;
+};
+
+// pc2 uses 8 consecutive io addresses
+static const int pc2_iosize = 8;
+static const int pc2a_iosize = 8;
+static const int pc2_2a_iosize = 16;
+
+// offset between io addresses of successive nec7210 registers
+static const int pc2a_reg_offset = 0x400;
+static const int pc2_reg_offset = 1;
+
+// interrupt service routine
+static irqreturn_t pc2_interrupt(int irq, void *arg);
+static irqreturn_t pc2a_interrupt(int irq, void *arg);
+
+// pc2 specific registers and bits
+
+// interrupt clear register address
+static const int pc2a_clear_intr_iobase = 0x2f0;
+static inline unsigned int CLEAR_INTR_REG(unsigned int irq)
+{
+	return pc2a_clear_intr_iobase + irq;
+}
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("GPIB driver for PC2/PC2a and compatible devices");
+
+/*
+ * GPIB interrupt service routines
+ */
+
+irqreturn_t pc2_interrupt(int irq, void *arg)
+{
+	struct gpib_board *board = arg;
+	struct pc2_priv *priv = board->private_data;
+	unsigned long flags;
+	irqreturn_t retval;
+
+	spin_lock_irqsave(&board->spinlock, flags);
+	retval = nec7210_interrupt(board, &priv->nec7210_priv);
+	spin_unlock_irqrestore(&board->spinlock, flags);
+	return retval;
+}
+
+irqreturn_t pc2a_interrupt(int irq, void *arg)
+{
+	struct gpib_board *board = arg;
+	struct pc2_priv *priv = board->private_data;
+	int status1, status2;
+	unsigned long flags;
+	irqreturn_t retval;
+
+	spin_lock_irqsave(&board->spinlock, flags);
+	// read interrupt status (also clears status)
+	status1 = read_byte(&priv->nec7210_priv, ISR1);
+	status2 = read_byte(&priv->nec7210_priv, ISR2);
+	/* clear interrupt circuit */
+	if (priv->irq)
+		outb(0xff, CLEAR_INTR_REG(priv->irq));
+	retval = nec7210_interrupt_have_status(board, &priv->nec7210_priv, status1, status2);
+	spin_unlock_irqrestore(&board->spinlock, flags);
+	return retval;
+}
+
+// wrappers for interface functions
+static int pc2_read(struct gpib_board *board, u8 *buffer, size_t length, int *end,
+		    size_t *bytes_read)
+{
+	struct pc2_priv *priv = board->private_data;
+
+	return nec7210_read(board, &priv->nec7210_priv, buffer, length, end, bytes_read);
+}
+
+static int pc2_write(struct gpib_board *board, u8 *buffer, size_t length, int send_eoi,
+		     size_t *bytes_written)
+{
+	struct pc2_priv *priv = board->private_data;
+
+	return nec7210_write(board, &priv->nec7210_priv, buffer, length, send_eoi, bytes_written);
+}
+
+static int pc2_command(struct gpib_board *board, u8 *buffer,
+		       size_t length, size_t *bytes_written)
+{
+	struct pc2_priv *priv = board->private_data;
+
+	return nec7210_command(board, &priv->nec7210_priv, buffer, length, bytes_written);
+}
+
+static int pc2_take_control(struct gpib_board *board, int synchronous)
+{
+	struct pc2_priv *priv = board->private_data;
+
+	return nec7210_take_control(board, &priv->nec7210_priv, synchronous);
+}
+
+static int pc2_go_to_standby(struct gpib_board *board)
+{
+	struct pc2_priv *priv = board->private_data;
+
+	return nec7210_go_to_standby(board, &priv->nec7210_priv);
+}
+
+static int pc2_request_system_control(struct gpib_board *board, int request_control)
+{
+	struct pc2_priv *priv = board->private_data;
+
+	return nec7210_request_system_control(board, &priv->nec7210_priv, request_control);
+}
+
+static void pc2_interface_clear(struct gpib_board *board, int assert)
+{
+	struct pc2_priv *priv = board->private_data;
+
+	nec7210_interface_clear(board, &priv->nec7210_priv, assert);
+}
+
+static void pc2_remote_enable(struct gpib_board *board, int enable)
+{
+	struct pc2_priv *priv = board->private_data;
+
+	nec7210_remote_enable(board, &priv->nec7210_priv, enable);
+}
+
+static int pc2_enable_eos(struct gpib_board *board, u8 eos_byte, int compare_8_bits)
+{
+	struct pc2_priv *priv = board->private_data;
+
+	return nec7210_enable_eos(board, &priv->nec7210_priv, eos_byte, compare_8_bits);
+}
+
+static void pc2_disable_eos(struct gpib_board *board)
+{
+	struct pc2_priv *priv = board->private_data;
+
+	nec7210_disable_eos(board, &priv->nec7210_priv);
+}
+
+static unsigned int pc2_update_status(struct gpib_board *board, unsigned int clear_mask)
+{
+	struct pc2_priv *priv = board->private_data;
+
+	return nec7210_update_status(board, &priv->nec7210_priv, clear_mask);
+}
+
+static int pc2_primary_address(struct gpib_board *board, unsigned int address)
+{
+	struct pc2_priv *priv = board->private_data;
+
+	return nec7210_primary_address(board, &priv->nec7210_priv, address);
+}
+
+static int pc2_secondary_address(struct gpib_board *board, unsigned int address, int enable)
+{
+	struct pc2_priv *priv = board->private_data;
+
+	return nec7210_secondary_address(board, &priv->nec7210_priv, address, enable);
+}
+
+static int pc2_parallel_poll(struct gpib_board *board, u8 *result)
+{
+	struct pc2_priv *priv = board->private_data;
+
+	return nec7210_parallel_poll(board, &priv->nec7210_priv, result);
+}
+
+static void pc2_parallel_poll_configure(struct gpib_board *board, u8 config)
+{
+	struct pc2_priv *priv = board->private_data;
+
+	nec7210_parallel_poll_configure(board, &priv->nec7210_priv, config);
+}
+
+static void pc2_parallel_poll_response(struct gpib_board *board, int ist)
+{
+	struct pc2_priv *priv = board->private_data;
+
+	nec7210_parallel_poll_response(board, &priv->nec7210_priv, ist);
+}
+
+static void pc2_serial_poll_response(struct gpib_board *board, u8 status)
+{
+	struct pc2_priv *priv = board->private_data;
+
+	nec7210_serial_poll_response(board, &priv->nec7210_priv, status);
+}
+
+static u8 pc2_serial_poll_status(struct gpib_board *board)
+{
+	struct pc2_priv *priv = board->private_data;
+
+	return nec7210_serial_poll_status(board, &priv->nec7210_priv);
+}
+
+static int pc2_t1_delay(struct gpib_board *board, unsigned int nano_sec)
+{
+	struct pc2_priv *priv = board->private_data;
+
+	return nec7210_t1_delay(board, &priv->nec7210_priv, nano_sec);
+}
+
+static void pc2_return_to_local(struct gpib_board *board)
+{
+	struct pc2_priv *priv = board->private_data;
+
+	nec7210_return_to_local(board, &priv->nec7210_priv);
+}
+
+static int allocate_private(struct gpib_board *board)
+{
+	struct pc2_priv *priv;
+
+	board->private_data = kzalloc_obj(struct pc2_priv);
+	if (!board->private_data)
+		return -ENOMEM;
+	priv = board->private_data;
+	init_nec7210_private(&priv->nec7210_priv);
+	return 0;
+}
+
+static void free_private(struct gpib_board *board)
+{
+	kfree(board->private_data);
+	board->private_data = NULL;
+}
+
+static int pc2_generic_attach(struct gpib_board *board, const struct gpib_board_config *config,
+			      enum nec7210_chipset chipset)
+{
+	struct pc2_priv *pc2_priv;
+	struct nec7210_priv *nec_priv;
+	int retval;
+
+	board->status = 0;
+	retval = allocate_private(board);
+	if (retval)
+		return retval;
+	pc2_priv = board->private_data;
+	nec_priv = &pc2_priv->nec7210_priv;
+	nec_priv->read_byte = nec7210_ioport_read_byte;
+	nec_priv->write_byte = nec7210_ioport_write_byte;
+	nec_priv->type = chipset;
+
+#ifndef PC2_DMA
+	/*
+	 * board->dev hasn't been initialized, so forget about DMA until this driver
+	 * is adapted to use isa_register_driver.
+	 */
+	if (config->ibdma)
+	// driver needs to be adapted to use isa_register_driver to get a struct device*
+		dev_err(board->gpib_dev, "DMA disabled for pc2 gpib");
+#else
+	if (config->ibdma) {
+		nec_priv->dma_buffer_length = 0x1000;
+		nec_priv->dma_buffer = dma_alloc_coherent(board->dev,
+							  nec_priv->dma_buffer_length, &
+							  nec_priv->dma_buffer_addr, GFP_ATOMIC);
+		if (!nec_priv->dma_buffer)
+			return -ENOMEM;
+
+		// request isa dma channel
+		if (request_dma(config->ibdma, "pc2")) {
+			dev_err(board->gpib_dev, "can't request DMA %d\n", config->ibdma);
+			return -1;
+		}
+		nec_priv->dma_channel = config->ibdma;
+	}
+#endif
+
+	return 0;
+}
+
+static int pc2_attach(struct gpib_board *board, const struct gpib_board_config *config)
+{
+	int isr_flags = 0;
+	struct pc2_priv *pc2_priv;
+	struct nec7210_priv *nec_priv;
+	int retval;
+
+	retval = pc2_generic_attach(board, config, NEC7210);
+	if (retval)
+		return retval;
+
+	pc2_priv = board->private_data;
+	nec_priv = &pc2_priv->nec7210_priv;
+	nec_priv->offset = pc2_reg_offset;
+
+	if (!request_region(config->ibbase, pc2_iosize, "pc2")) {
+		dev_err(board->gpib_dev, "ioports are already in use\n");
+		return -EBUSY;
+	}
+	nec_priv->iobase = config->ibbase;
+
+	nec7210_board_reset(nec_priv, board);
+
+	// install interrupt handler
+	if (config->ibirq) {
+		if (request_irq(config->ibirq, pc2_interrupt, isr_flags, "pc2", board))	{
+			dev_err(board->gpib_dev, "can't request IRQ %d\n", config->ibirq);
+			return -EBUSY;
+		}
+	}
+	pc2_priv->irq = config->ibirq;
+	/* poll so we can detect assertion of ATN */
+	if (gpib_request_pseudo_irq(board, pc2_interrupt)) {
+		dev_err(board->gpib_dev, "failed to allocate pseudo_irq\n");
+		return -1;
+	}
+	/* set internal counter register for 8 MHz input clock */
+	write_byte(nec_priv, ICR | 8, AUXMR);
+
+	nec7210_board_online(nec_priv, board);
+
+	return 0;
+}
+
+static void pc2_detach(struct gpib_board *board)
+{
+	struct pc2_priv *pc2_priv = board->private_data;
+	struct nec7210_priv *nec_priv;
+
+	if (pc2_priv) {
+		nec_priv = &pc2_priv->nec7210_priv;
+#ifdef PC2_DMA
+		if (nec_priv->dma_channel)
+			free_dma(nec_priv->dma_channel);
+#endif
+		gpib_free_pseudo_irq(board);
+		if (pc2_priv->irq)
+			free_irq(pc2_priv->irq, board);
+		if (nec_priv->iobase) {
+			nec7210_board_reset(nec_priv, board);
+			release_region(nec_priv->iobase, pc2_iosize);
+		}
+		if (nec_priv->dma_buffer) {
+			dma_free_coherent(board->dev, nec_priv->dma_buffer_length,
+					  nec_priv->dma_buffer, nec_priv->dma_buffer_addr);
+			nec_priv->dma_buffer = NULL;
+		}
+	}
+	free_private(board);
+}
+
+static int pc2a_common_attach(struct gpib_board *board, const struct gpib_board_config *config,
+			      unsigned int num_registers, enum nec7210_chipset chipset)
+{
+	unsigned int i, j;
+	struct pc2_priv *pc2_priv;
+	struct nec7210_priv *nec_priv;
+	int retval;
+
+	retval = pc2_generic_attach(board, config, chipset);
+	if (retval)
+		return retval;
+
+	pc2_priv = board->private_data;
+	nec_priv = &pc2_priv->nec7210_priv;
+	nec_priv->offset = pc2a_reg_offset;
+
+	switch (config->ibbase) {
+	case 0x02e1:
+	case 0x22e1:
+	case 0x42e1:
+	case 0x62e1:
+		break;
+	default:
+		dev_err(board->gpib_dev, "PCIIa base range invalid, must be one of 0x[0246]2e1, but is 0x%x\n",
+			config->ibbase);
+		return -1;
+	}
+
+	if (config->ibirq) {
+		if (config->ibirq < 2 || config->ibirq > 7) {
+			dev_err(board->gpib_dev, "illegal interrupt level %i\n",
+				config->ibirq);
+			return -1;
+		}
+	} else	{
+		dev_err(board->gpib_dev, "interrupt disabled, using polling mode (slow)\n");
+	}
+#ifdef CHECK_IOPORTS
+	unsigned int err = 0;
+
+	for (i = 0; i < num_registers; i++) {
+		if (check_region(config->ibbase + i * pc2a_reg_offset, 1))
+			err++;
+	}
+	if (config->ibirq && check_region(pc2a_clear_intr_iobase + config->ibirq, 1))
+		err++;
+	if (err) {
+		dev_err(board->gpib_dev, "ioports are already in use");
+		return -EBUSY;
+	}
+#endif
+	for (i = 0; i < num_registers; i++) {
+		if (!request_region(config->ibbase +
+					i * pc2a_reg_offset, 1, "pc2a")) {
+			dev_err(board->gpib_dev, "ioports are already in use");
+			for (j = 0; j < i; j++)
+				release_region(config->ibbase +
+					j * pc2a_reg_offset, 1);
+			return -EBUSY;
+		}
+	}
+	nec_priv->iobase = config->ibbase;
+	if (config->ibirq) {
+		if (!request_region(pc2a_clear_intr_iobase + config->ibirq, 1, "pc2a"))  {
+			dev_err(board->gpib_dev, "ioports are already in use");
+			return -1;
+		}
+		pc2_priv->clear_intr_addr = pc2a_clear_intr_iobase + config->ibirq;
+		if (request_irq(config->ibirq, pc2a_interrupt, 0, "pc2a", board)) {
+			dev_err(board->gpib_dev, "can't request IRQ %d\n", config->ibirq);
+			return -EBUSY;
+		}
+	}
+	pc2_priv->irq = config->ibirq;
+	/* poll so we can detect assertion of ATN */
+	if (gpib_request_pseudo_irq(board, pc2_interrupt)) {
+		dev_err(board->gpib_dev, "failed to allocate pseudo_irq\n");
+		return -1;
+	}
+
+	// make sure interrupt is clear
+	if (pc2_priv->irq)
+		outb(0xff, CLEAR_INTR_REG(pc2_priv->irq));
+
+	nec7210_board_reset(nec_priv, board);
+
+	/* set internal counter register for 8 MHz input clock */
+	write_byte(nec_priv, ICR | 8, AUXMR);
+
+	nec7210_board_online(nec_priv, board);
+
+	return 0;
+}
+
+static int pc2a_attach(struct gpib_board *board, const struct gpib_board_config *config)
+{
+	return pc2a_common_attach(board, config, pc2a_iosize, NEC7210);
+}
+
+static int pc2a_cb7210_attach(struct gpib_board *board, const struct gpib_board_config *config)
+{
+	return pc2a_common_attach(board, config, pc2a_iosize, CB7210);
+}
+
+static int pc2_2a_attach(struct gpib_board *board, const struct gpib_board_config *config)
+{
+	return pc2a_common_attach(board, config, pc2_2a_iosize, NAT4882);
+}
+
+static void pc2a_common_detach(struct gpib_board *board, unsigned int num_registers)
+{
+	int i;
+	struct pc2_priv *pc2_priv = board->private_data;
+	struct nec7210_priv *nec_priv;
+
+	if (pc2_priv) {
+		nec_priv = &pc2_priv->nec7210_priv;
+#ifdef PC2_DMA
+		if (nec_priv->dma_channel)
+			free_dma(nec_priv->dma_channel);
+#endif
+		gpib_free_pseudo_irq(board);
+		if (pc2_priv->irq)
+			free_irq(pc2_priv->irq, board);
+		if (nec_priv->iobase) {
+			nec7210_board_reset(nec_priv, board);
+			for (i = 0; i < num_registers; i++)
+				release_region(nec_priv->iobase +
+					       i * pc2a_reg_offset, 1);
+		}
+		if (pc2_priv->clear_intr_addr)
+			release_region(pc2_priv->clear_intr_addr, 1);
+		if (nec_priv->dma_buffer) {
+			dma_free_coherent(board->dev, nec_priv->dma_buffer_length,
+					  nec_priv->dma_buffer,
+					  nec_priv->dma_buffer_addr);
+			nec_priv->dma_buffer = NULL;
+		}
+	}
+	free_private(board);
+}
+
+static void pc2a_detach(struct gpib_board *board)
+{
+	pc2a_common_detach(board, pc2a_iosize);
+}
+
+static void pc2_2a_detach(struct gpib_board *board)
+{
+	pc2a_common_detach(board, pc2_2a_iosize);
+}
+
+static struct gpib_interface pc2_interface = {
+	.name =	"pcII",
+	.attach =	pc2_attach,
+	.detach =	pc2_detach,
+	.read =	pc2_read,
+	.write =	pc2_write,
+	.command =	pc2_command,
+	.take_control =	pc2_take_control,
+	.go_to_standby =	pc2_go_to_standby,
+	.request_system_control =	pc2_request_system_control,
+	.interface_clear =	pc2_interface_clear,
+	.remote_enable =	pc2_remote_enable,
+	.enable_eos =	pc2_enable_eos,
+	.disable_eos =	pc2_disable_eos,
+	.parallel_poll =	pc2_parallel_poll,
+	.parallel_poll_configure =	pc2_parallel_poll_configure,
+	.parallel_poll_response =	pc2_parallel_poll_response,
+	.local_parallel_poll_mode = NULL, // XXX
+	.line_status =	NULL,
+	.update_status =	pc2_update_status,
+	.primary_address =	pc2_primary_address,
+	.secondary_address =	pc2_secondary_address,
+	.serial_poll_response =	pc2_serial_poll_response,
+	.serial_poll_status =	pc2_serial_poll_status,
+	.t1_delay = pc2_t1_delay,
+	.return_to_local = pc2_return_to_local,
+};
+
+static struct gpib_interface pc2a_interface = {
+	.name =	"pcIIa",
+	.attach =	pc2a_attach,
+	.detach =	pc2a_detach,
+	.read =	pc2_read,
+	.write =	pc2_write,
+	.command =	pc2_command,
+	.take_control =	pc2_take_control,
+	.go_to_standby =	pc2_go_to_standby,
+	.request_system_control =	pc2_request_system_control,
+	.interface_clear =	pc2_interface_clear,
+	.remote_enable =	pc2_remote_enable,
+	.enable_eos =	pc2_enable_eos,
+	.disable_eos =	pc2_disable_eos,
+	.parallel_poll =	pc2_parallel_poll,
+	.parallel_poll_configure =	pc2_parallel_poll_configure,
+	.parallel_poll_response =	pc2_parallel_poll_response,
+	.local_parallel_poll_mode = NULL, // XXX
+	.line_status =	NULL,
+	.update_status =	pc2_update_status,
+	.primary_address =	pc2_primary_address,
+	.secondary_address =	pc2_secondary_address,
+	.serial_poll_response =	pc2_serial_poll_response,
+	.serial_poll_status =	pc2_serial_poll_status,
+	.t1_delay = pc2_t1_delay,
+	.return_to_local = pc2_return_to_local,
+};
+
+static struct gpib_interface pc2a_cb7210_interface = {
+	.name =	"pcIIa_cb7210",
+	.attach =	pc2a_cb7210_attach,
+	.detach =	pc2a_detach,
+	.read =	pc2_read,
+	.write =	pc2_write,
+	.command =	pc2_command,
+	.take_control =	pc2_take_control,
+	.go_to_standby =	pc2_go_to_standby,
+	.request_system_control =	pc2_request_system_control,
+	.interface_clear =	pc2_interface_clear,
+	.remote_enable =	pc2_remote_enable,
+	.enable_eos =	pc2_enable_eos,
+	.disable_eos =	pc2_disable_eos,
+	.parallel_poll =	pc2_parallel_poll,
+	.parallel_poll_configure =	pc2_parallel_poll_configure,
+	.parallel_poll_response =	pc2_parallel_poll_response,
+	.local_parallel_poll_mode = NULL, // XXX
+	.line_status =	NULL, // XXX
+	.update_status =	pc2_update_status,
+	.primary_address =	pc2_primary_address,
+	.secondary_address =	pc2_secondary_address,
+	.serial_poll_response =	pc2_serial_poll_response,
+	.serial_poll_status =	pc2_serial_poll_status,
+	.t1_delay = pc2_t1_delay,
+	.return_to_local = pc2_return_to_local,
+};
+
+static struct gpib_interface pc2_2a_interface = {
+	.name =	"pcII_IIa",
+	.attach =	pc2_2a_attach,
+	.detach =	pc2_2a_detach,
+	.read =	pc2_read,
+	.write =	pc2_write,
+	.command =	pc2_command,
+	.take_control =	pc2_take_control,
+	.go_to_standby =	pc2_go_to_standby,
+	.request_system_control =	pc2_request_system_control,
+	.interface_clear =	pc2_interface_clear,
+	.remote_enable =	pc2_remote_enable,
+	.enable_eos =	pc2_enable_eos,
+	.disable_eos =	pc2_disable_eos,
+	.parallel_poll =	pc2_parallel_poll,
+	.parallel_poll_configure =	pc2_parallel_poll_configure,
+	.parallel_poll_response =	pc2_parallel_poll_response,
+	.local_parallel_poll_mode = NULL, // XXX
+	.line_status =	NULL,
+	.update_status =	pc2_update_status,
+	.primary_address =	pc2_primary_address,
+	.secondary_address =	pc2_secondary_address,
+	.serial_poll_response =	pc2_serial_poll_response,
+	.serial_poll_status =	pc2_serial_poll_status,
+	.t1_delay = pc2_t1_delay,
+	.return_to_local = pc2_return_to_local,
+};
+
+static int __init pc2_init_module(void)
+{
+	int ret;
+
+	ret = gpib_register_driver(&pc2_interface, THIS_MODULE);
+	if (ret) {
+		pr_err("gpib_register_driver failed: error = %d\n", ret);
+		return ret;
+	}
+
+	ret = gpib_register_driver(&pc2a_interface, THIS_MODULE);
+	if (ret) {
+		pr_err("gpib_register_driver failed: error = %d\n", ret);
+		goto err_pc2a;
+	}
+
+	ret = gpib_register_driver(&pc2a_cb7210_interface, THIS_MODULE);
+	if (ret) {
+		pr_err("gpib_register_driver failed: error = %d\n", ret);
+		goto err_cb7210;
+	}
+
+	ret = gpib_register_driver(&pc2_2a_interface, THIS_MODULE);
+	if (ret) {
+		pr_err("gpib_register_driver failed: error = %d\n", ret);
+		goto err_pc2_2a;
+	}
+
+	return 0;
+
+err_pc2_2a:
+	gpib_unregister_driver(&pc2a_cb7210_interface);
+err_cb7210:
+	gpib_unregister_driver(&pc2a_interface);
+err_pc2a:
+	gpib_unregister_driver(&pc2_interface);
+
+	return ret;
+}
+
+static void __exit pc2_exit_module(void)
+{
+	gpib_unregister_driver(&pc2_interface);
+	gpib_unregister_driver(&pc2a_interface);
+	gpib_unregister_driver(&pc2a_cb7210_interface);
+	gpib_unregister_driver(&pc2_2a_interface);
+}
+
+module_init(pc2_init_module);
+module_exit(pc2_exit_module);
+