Re: RFC: Compact Flash True IDE Mode Driver

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On Feb 13, 2006, at 2:21 PM, Bartlomiej Zolnierkiewicz wrote:

On 2/13/06, Kumar Gala <[email protected]> wrote:
On Feb 13, 2006, at 10:53 AM, Bartlomiej Zolnierkiewicz wrote:

On 2/13/06, Kumar Gala <[email protected]> wrote:

+static void cfide_outsl(unsigned long port, void *addr, u32 count)
+{
+       panic("outsl unsupported");
+}
This will panic as soon as somebody tries to enable 32-bit I/O
using hdparm.  Please add ide_hwif_t.no_io_32bit flag and teach
ide-disk.c:ide_disk_setup() about it (separate patch).
I'm not sure I follow this, can you expand.
Do "hdparm -c 2 /dev/hdx" first and then read/write to the device
and you should see it. :)

We need to make "hdparm -c 2" (and "hdparm -c 3") unsupported
(see how "io_32bit" setting is handled in ide_add_generic_settings()
and how it can be read-only or read-write setting depending on the
value of drive->no_io_32bit).

To do this we need to set drive->no_io_32bit to 1 (see how
ide_disk_setup() handles it).  Unfortunately 32-bit I/O capability
is based on capabilities of both host and device so we have to
add new flag hwif->no_io_32bit to indicate that host doesn't
support 32-bit I/O.
This all make sense, should I check for hwif->no_io_32bit in
idedisk_setup() and set drive->no_io_32bit to 1 if hwif->no_io_32bit
is 1 or do this the test in ide_add_generic_settings()?
Good question.  idedisk_setup() seems more logical but in the current
model "io_32bit" setting is still accessible without ide-disk driver through
/proc/ide/ interface so...

Moreover the current drive->no_io_32bit code in ide-disk is wrong:
* it shouldn't be overriding drive->no_io_32bit flag if it is 1
* doing this in ide-disk may be too late w.r.t. ide_add_generic_settings()
Therefore your previous suggestion is the right one - the best place
to deal with ->no_io_32bit is ide-probe.c - doing this for all drives at
the end of probe_hwif() should fix all above issues.
Now I'm confused.  If I understand the code, what I want is for the  
"io_32bit" setting to have its RW field set to SETTING_READ, such  
that drive->no_io_32bit can NOT be changed.  Additionally, I want it  
set to 1 if hwif->no_io_32bit is 1.
Are you saying that at the end of probe_hwif() I should iterate over  
the drives for that hwif and set drive->no_io_32bit to 1 if hwif- 
>no_io_32bit is 1?  If so, can I do this in the last loop that  
already exists that iterates over the drives?
Will I not also want to test hwif->no_io_32bit in idedisk_setup() to  
ensure that it can only set driver->no_io_32bit to 0 if hwif- 
>no_io32bit is 0?
- kumar

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