Messages in this thread Patch in this message | | | From | matwey@sai ... | Subject | [PATCHv4 2/2] parport: parport_pc: Implement CPU model check to cut off false-positives | Date | Fri, 18 Jul 2014 11:12:55 +0400 |
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From: "Matwey V. Kornilov" <matwey@sai.msu.ru>
The code in intel_bug_present is known to produce much false-positives. It is believed that the affected by the bug hardware are used with either Intel 80486 or Pentium.
Perform the check only when the kernel configured as CONFIG_X86_32, then use cpuinfo_x86 of the first available CPU to check the model and run initial check code.
Suggested-by: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> Tested-by: Heiko Andreas Sommer <hsommer@eso.org> Signed-off-by: Matwey V. Kornilov <matwey@sai.msu.ru> --- drivers/parport/parport_pc.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-)
diff --git a/drivers/parport/parport_pc.c b/drivers/parport/parport_pc.c index a6eaafb..6b28f9f 100644 --- a/drivers/parport/parport_pc.c +++ b/drivers/parport/parport_pc.c @@ -65,6 +65,7 @@ #include <linux/parport_pc.h> #include <linux/via.h> #include <asm/parport.h> +#include <asm/processor.h> #define PARPORT_PC_MAX_PORTS PARPORT_MAX @@ -1702,7 +1703,11 @@ static int parport_ECP_supported(struct parport *pb) } #endif -static int intel_bug_present(struct parport *pb) +/* It is believed that CPU model correlates with buggy LPT chipset model. + Here we check that or CPU is elder than Pentium Pro: either 80486 or Pentium. + If it is then we perform The Check. */ +#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 +1730,20 @@ static int intel_bug_present(struct parport *pb) return bug_present; } +static int intel_bug_present(struct parport *pb) +{ + struct cpuinfo_x86 *c = &cpu_data(0); + + if (c->x86_vendor == X86_VENDOR_INTEL && (c->x86 == 4 || c->x86 == 5)) + return intel_bug_present_check_epp(pb); + return 0; +} +#else +static int intel_bug_present(struct parport *pb) +{ + return 0; +} +#endif static int parport_ECPPS2_supported(struct parport *pb) { -- 1.8.1.4
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