On 8/24/23 01:35, Sergey Shtylyov wrote:
On 8/23/23 1:13 AM, Michael Schmitz wrote:
Some users of pata_falcon on Q40 have IDE disks in default
IDE little endian byte order, whereas legacy disks use
host-native big-endian byte order as on the Atari Falcon.
Add module parameter 'data_swab' to allow connecting drives
with non-native data byte order. Drives selected by the
data_swap bit mask will have their user data byte-swapped to
host byte order, i.e. 'pata_falcon.data_swab=2' will byte-swap
all user data on drive B, leaving data on drive A in native
byte order. On Q40, drives on a second IDE interface may be
added to the bit mask as bits 2 and 3.
Default setting is no byte swapping, i.e. compatibility with
the native Falcon or Q40 operating system disk format.
Cc: William R Sowerbutts <will@xxxxxxxxxxxxxx>
Cc: Finn Thain <fthain@xxxxxxxxxxxxxx>
Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Tested-by: William R Sowerbutts <will@xxxxxxxxxxxxxx>
Signed-off-by: Michael Schmitz <schmitzmic@xxxxxxxxx>
Reviewed-by: Sergey Shtylyov <s.shtylyov@xxxxxx>
[...]
diff --git a/drivers/ata/pata_falcon.c b/drivers/ata/pata_falcon.c
index 3841ea200bcb..7cf15bd9764a 100644
--- a/drivers/ata/pata_falcon.c
+++ b/drivers/ata/pata_falcon.c
[...]
@@ -194,6 +199,9 @@ static int __init pata_falcon_init_one(struct platform_device *pdev)
ata_port_desc(ap, "cmd %px ctl %px data %pa",
base, ctl_base, &ap->ioaddr.data_addr);
+ ap->private_data = (void *)(uintptr_t)(pdev->id > 0 ?
+ pata_falcon_swap_mask >> 2 : pata_falcon_swap_mask);
How about:
ap->private_data = (void *)(uintptr_t)(pata_falcon_swap_mask >>
(pdev->id > 0 ? 2 : 0));
This is so hard to decode... Let's please spell this out.
Something like:
int shift;
if (pdev->id)
shift = 2;
else
shift = 0;
ap->private_data = (uintptr_t)(pata_falcon_swap_mask >> shift);
This is initialization, so no need to try to optimize and rather privilege clear
code.
[...]
MBR, Sergey
--
Damien Le Moal
Western Digital Research
