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ahc(4): Default to memory mapped IO

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When this driver was written it made sense to make this default to off,
but these days almost all BIOSses will do the right thing. Furthermore
non-mmio communication only works on Intel architectures.

So lets default to allowing mmio, but not change the semantics of the
AHC_ALLOW_MEMIO flag to not break existing installs. Also document the
already existing hint.ahc.<unit>.allow_memio.

Signed-off-by: HP van Braam <hp@tmm.cx>
Reviewed by: imp (small style tweak)
Pull Request: https://github.com/freebsd/freebsd-src/pull/1219
This commit is contained in:
HP van Braam 2024-05-09 20:13:03 -06:00 committed by Warner Losh
parent 09025a7147
commit c733dc7a6f
5 changed files with 15 additions and 13 deletions
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13
share/man/man4/ahc.4
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@ -131,7 +131,7 @@ target on multiple SCSI IDs.
.Pp
To allow PCI adapters to use memory mapped I/O if enabled:
.Pp
.Cd options AHC_ALLOW_MEMIO
.Cd options AHC_ALLOW_MEMIO=(0 -- disabled, 1 -- enabled)
.Bd -ragged -offset indent
Memory mapped I/O is more efficient than the alternative, programmed I/O.
Most PCI BIOSes will map devices so that either technique for communicating
@ -141,12 +141,13 @@ the chip for memory mapped I/O. The typical symptom of this problem is a
system hang if memory mapped I/O is attempted.
.Pp
Most modern motherboards perform the initialization correctly and work fine
with this option enabled.
with this option enabled and it is the default. This option can also be
dynamically configued through a device hint documented below.
.Ed
.Pp
To statically configure one or more controllers to assume the target role:
.Pp
.Cd options AHC_TMODE_ENABLE <bitmask of units>
.Cd options AHC_TMODE_ENABLE=<bitmask of units>
.Bd -ragged -offset indent
The value assigned to this option should be a bitmap of all units where target
mode is desired. For example, a value of 0x25, would enable target mode on
@ -163,7 +164,11 @@ The following options are switchable by setting values in
They are:
.Bl -tag -width indent
.It Va hint.ahc. Ns Ar N Ns Va .tmode_enable
A hint to define whether the SCSI target mode is enabled (0 -- disabled, 1 -- enabled).
A hint to define whether the SCSI target mode is enabled, defaults to disabled
(0 -- disabled, 1 -- enabled).
.It Va hint.ahc. Ns Ar N Ns Va .allow_memio
A hint to define whether memory mapped io is enabled or disabled for this
adapter, defaults to enabled (0 -- disabled, 1 -- enabled).
.El
.Ed
.Sh HARDWARE

12
sys/dev/aic7xxx/ahc_pci.c
View File

@ -138,7 +138,7 @@ ahc_pci_map_registers(struct ahc_softc *ahc)
struct resource *regs;
int regs_type;
int regs_id;
int allow_memio;
int allow_memio = 1;
regs = NULL;
regs_type = 0;
@ -150,14 +150,14 @@ ahc_pci_map_registers(struct ahc_softc *ahc)
"allow_memio", &allow_memio) != 0) {
if (bootverbose)
device_printf(ahc->dev_softc, "Defaulting to MEMIO ");
#ifdef AHC_ALLOW_MEMIO
if (bootverbose)
printf("on\n");
allow_memio = 1;
#else
#if defined(AHC_ALLOW_MEMIO) && (AHC_ALLOW_MEMIO == 0)
if (bootverbose)
printf("off\n");
allow_memio = 0;
#else
if (bootverbose)
printf("on\n");
allow_memio = 1;
#endif
}

1
sys/powerpc/conf/GENERIC
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@ -119,7 +119,6 @@ device siis # SiliconImage SiI3124/SiI3132/SiI3531 SATA
# SCSI Controllers
device ahc # AHA2940 and onboard AIC7xxx devices
options AHC_ALLOW_MEMIO # Attempt to use memory mapped I/O
device isp # Qlogic family
device ispfw # Firmware module for Qlogic host adapters
device mpt # LSI-Logic MPT-Fusion

1
sys/powerpc/conf/GENERIC64
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@ -137,7 +137,6 @@ device nvd # expose NVMe namespaces as disks, depends on nvme
# SCSI Controllers
device aacraid # Adaptec by PMC RAID
device ahc # AHA2940 and onboard AIC7xxx devices
options AHC_ALLOW_MEMIO # Attempt to use memory mapped I/O
device isp # Qlogic family
device ispfw # Firmware module for Qlogic host adapters
device mrsas # LSI/Avago MegaRAID SAS/SATA, 6Gb/s and 12Gb/s

1
sys/powerpc/conf/GENERIC64LE
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@ -133,7 +133,6 @@ device nvd # expose NVMe namespaces as disks, depends on nvme
# SCSI Controllers
device aacraid # Adaptec by PMC RAID
device ahc # AHA2940 and onboard AIC7xxx devices
options AHC_ALLOW_MEMIO # Attempt to use memory mapped I/O
device isp # Qlogic family
device ispfw # Firmware module for Qlogic host adapters
device mrsas # LSI/Avago MegaRAID SAS/SATA, 6Gb/s and 12Gb/s