Hi Finn,
thanks for your review!
Am 16.08.2023 um 12:23 schrieb Finn Thain:
Hi Michael,
Thanks for fixing this.
On Wed, 16 Aug 2023, Michael Schmitz wrote:
With commit 44b1fbc0f5f3 ("m68k/q40: Replace q40ide driver
with pata_falcon and falconide"), the Q40 IDE driver was
replaced by pata_falcon.c (and the later obsoleted
falconide.c).
"the latter also made falconide obsolete".
I actually meant 'later' - the patch changed both falconide.c and
pata_falcon.c, and falconide.c was later obsoleted.
That's now history, may as well drop mention of falconide.c!
Both IO and memory resources were defined for the Q40 IDE
platform device, but definition of the IDE register addresses
was modeled after the Falcon case, both in use of the memory
resources and in including register scale and byte vs. word
offset in the address.
This was correct for the Falcon case, which does not apply
any address translation to the register addresses. In the
Q40 case, all of device base address, byte access offset
and register scaling is included in the platform specific
ISA access translation (in asm/mm_io.h).
As a consequence, such address translation gets applied
twice, and register addresses are mangled.
Use the device base address from the platform IO resource,
and use standard register offsets from that base in order
to calculate register addresses (the IO address translation
will then apply the correct ISA window base and scaling).
Encode PIO_OFFSET into IO port addresses for all registers
except the data transfer register. Encode the MMIO offset
there (pata_falcon_data_xfer() directly uses raw IO with
no address translation).
Add module parameter 'data_swap' to allow connecting drives
How about "data_swab"? A "data swap" could be anything, and a byte swap
could be a number of things depending on the size of a word. Here we are
swapping every pair of bytes, which is called "swab" according to dd's and
libc's terminology.
Good point. I'll change that.
with non-native data byte order. Drives selected by the
data_swap bit mask will have their user data swapped to host
byte order, i.e. 'pata_falcon.data_swap=2' will swap all user
data on drive B, leaving data on drive A in native order.
Reported-by: William R Sowerbutts <will@xxxxxxxxxxxxxx>
Closes: https://lore.kernel.org/r/CAMuHMdUU62jjunJh9cqSqHT87B0H0A4udOOPs=WN7WZKpcagVA@xxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/CAMuHMdUU62jjunJh9cqSqHT87B0H0A4udOOPs=WN7WZKpcagVA@xxxxxxxxxxxxxx
Fixes: 44b1fbc0f5f3 ("m68k/q40: Replace q40ide driver with pata_falcon and falconide")
Cc: Finn Thain <fthain@xxxxxxxxxxxxxx>
Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Signed-off-by: Michael Schmitz <schmitzmic@xxxxxxxxx>
---
Changes from v2:
- add driver parameter 'data_swap' as bit mask for drives to swap
Changes from v1:
Finn Thain:
- take care to supply IO address suitable for ioread8/iowrite8
- use MMIO address for data transfer
---
drivers/ata/pata_falcon.c | 90 ++++++++++++++++++++++++++++++---------
1 file changed, 69 insertions(+), 21 deletions(-)
diff --git a/drivers/ata/pata_falcon.c b/drivers/ata/pata_falcon.c
index 996516e64f13..e6038eca39d6 100644
--- a/drivers/ata/pata_falcon.c
+++ b/drivers/ata/pata_falcon.c
@@ -33,6 +33,16 @@
#define DRV_NAME "pata_falcon"
#define DRV_VERSION "0.1.0"
+static int pata_falcon_swap_mask = 0;
+
Looks like you need to run checkpatch (static variable initialized to 0).
Forgot to drop that after tests before I got the parameter to work.
+module_param_named(data_swap, pata_falcon_swap_mask, int, 0444);
+MODULE_PARM_DESC(data_swap, "Data byte swap enable/disable (0x1==drive1, 0x2==drive2, default==0)");
The help string does not mention that this is a bit mask (bit 0 = drive 1,
Right -I'll add 'bit mask' there.
etc.)
+
+struct pata_falcon_priv {
+ unsigned int swap_mask;
+ bool swap_data;
+};
+
static const struct scsi_host_template pata_falcon_sht = {
ATA_PIO_SHT(DRV_NAME),
};
@@ -44,13 +54,15 @@ static unsigned int pata_falcon_data_xfer(struct ata_queued_cmd *qc,
struct ata_device *dev = qc->dev;
struct ata_port *ap = dev->link->ap;
void __iomem *data_addr = ap->ioaddr.data_addr;
+ struct pata_falcon_priv *priv = ap->private_data;
unsigned int words = buflen >> 1;
struct scsi_cmnd *cmd = qc->scsicmd;
+ int dev_id = cmd->device->sdev_target->id;
bool swap = 1;
if (dev->class == ATA_DEV_ATA && cmd &&
!blk_rq_is_passthrough(scsi_cmd_to_rq(cmd)))
- swap = 0;
+ swap = priv->swap_data && (priv->swap_mask & 1<<dev_id);
I suggest writing that as priv->swap_mask & BIT(dev_id). (I wonder why
checkpatch does not ask for whitespace around the << operator...)
Right - I also wonder whether using priv->swap_data to skip the bit test
in the most likely case (no byte swapping) is actually worth it.
I'll split this into bugfix and byte swap parts
Where should this go - linux-ide for sure, but is Bartlomiej still the
correct maintainer?
Cheers,
Michael
