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Date:   Wed, 16 Nov 2022 21:36:09 +0000 (GMT)
From:   "Maciej W. Rozycki" <macro@orcam.me.uk>
To:     Sudip Mukherjee <sudipm.mukherjee@gmail.com>
cc:     linux-kernel@vger.kernel.org
Subject: [PATCH 5/6] parport_pc: Add an ECR mask field for PCI devices
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Add a bitmask field specifying writable ECR bits for PCI devices and 
apply it via `__parport_pc_probe_port'.

Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
---
 drivers/parport/parport_pc.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

linux-parport-pc-pci-ecr-write.diff
Index: linux-macro/drivers/parport/parport_pc.c
===================================================================
--- linux-macro.orig/drivers/parport/parport_pc.c
+++ linux-macro/drivers/parport/parport_pc.c
@@ -2662,6 +2662,10 @@ static struct parport_pc_pci {
 	/* Bit field of parport modes to exclude. */
 	unsigned int mode_mask;
 
+	/* If non-zero, sets the bitmask of writable ECR bits.  In that
+	 * case additionally bit 0 will be forcibly set on writes. */
+	unsigned char ecr_writable;
+
 	/* If set, this is called immediately after pci_enable_device.
 	 * If it returns non-zero, no probing will take place and the
 	 * ports will not be used. */
@@ -2868,7 +2872,8 @@ static int parport_pc_pci_probe(struct p
 			__parport_pc_probe_port(io_lo, io_hi, irq,
 						PARPORT_DMA_NONE, &dev->dev,
 						IRQF_SHARED,
-						cards[i].mode_mask, 0);
+						cards[i].mode_mask,
+						cards[i].ecr_writable);
 		if (data->ports[count])
 			count++;
 	}