[Linux-parport] [PATCHv5 2/2] parport: parport_pc: Implement architecture and device check to cut off false-positives

matwey at sai.msu.ru matwey at sai.msu.ru
Wed Aug 27 01:07:44 PDT 2014

From: "Matwey V. Kornilov" <matwey at sai.msu.ru>

We definitely know that only x86 (32-bit) architecture is affected by the issue, so implement a stub instead of the actual check for other architectures.

We also know that motherboard LPT chipset is affected, so the port is either come from
  parport_pc_init (when `io' module param is used) or
  parport_pc_find_isa_ports (when default LPT ports are probbed: 0x378, 0x278, 0x3bc).
In both cases the port considered as 'legacy' and `dev' member of struct parport is NULL. See also comments for `struct parport' in parport.h

Signed-off-by: Matwey V. Kornilov <matwey at sai.msu.ru>
 drivers/parport/parport_pc.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/parport/parport_pc.c b/drivers/parport/parport_pc.c
index fedc06b..5b27747 100644
--- a/drivers/parport/parport_pc.c
+++ b/drivers/parport/parport_pc.c
@@ -1702,7 +1702,8 @@ static int parport_ECP_supported(struct parport *pb)
-static int intel_bug_present(struct parport *pb)
+#ifdef CONFIG_X86_32
+static int intel_bug_present_check_epp(struct parport *pb)
 	const struct parport_pc_private *priv = pb->private_data;
 	int bug_present = 0;
@@ -1725,6 +1726,21 @@ static int intel_bug_present(struct parport *pb)
 	return bug_present;
+static int intel_bug_present(struct parport *pb)
+/* Check whether the device is legacy, not PCI or PCMCIA. Only legacy is known to be affected. */
+	if (pb->dev != NULL) {
+		return 0;
+	}
+	return intel_bug_present_check_epp(pb);
+static int intel_bug_present(struct parport *pb)
+	return 0;
+#endif /* CONFIG_X86_32 */
 static int parport_ECPPS2_supported(struct parport *pb)

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