Re: writable mmc profiles actually are writable

[Pat LaVarre <p.lavarre@ieee.org>]

> From: Jens Axboe ...
> Please add the GET_CONFIGURATION stuff to cdrom.c
> instead so it works with ide-cd as well ...

Help!  I do not know Where to add this code.

Tell me again where is the one place I can patch to add discovery of
more capability in both sr and ide-cd devices?

Closer study now again seemingly tells me that ide-cd and sr
independently work to try the op x5A Mode Sense of page x2A Capabilities
and not op x46 Get Configuration.

On this point do we agree?

drivers/ide/ide.cd ide_cdrom_get_capabilities speaks thru
drivers/cdrom/cdrom.c cdrom_mode_sense, aye.

drivers/scsi/sr.c get_capabilities speaks instead thru
drivers/scsi/scsi_lib.c scsi_mode_sense.

printk tells me with a usb-storage.ko drive I get as far as 'dd: opening
`/dev/scd0': Read-only file system' without cdrom.c cdrom_mode_sense
ever being called.  With an ide-cd.ko driver, I do see cdrom_mode_sense
called.  The ide-cd command is -x 5A 00 2A:00:00:00 00 00:18 00 -i x18,
rather than the less polite -x 5A 00 2A:00:00:00 00 00:80 00 -i x80 of
sr.

Does a place exist in drivers/cdrom where I can insert code to run after
ide-cd and sr finish their op x5A Mode Sense?

Have I misunderstood your request?  Did you actually mean to tell me to
go so far as to move the op x5A Mode Sense out of ide-cd and out of sr
and into cdrom?  If indeed I should move those out, to where should I
move them?

> The ->generic_packet() hook and
> cdrom_generic_command was invented to solve
> this code duplication.

Found, thank you:

I see cdrom.c cdrom_mode_sense speaks thru cdo->generic_packet.

I see include/linux/cdrom.h defines a struct cdrom_generic_command that
field-for-field matches other simplifications of scsi/sg.h sg_io_hdr
that appear on the web, such as my own plscsi and gccscsi.

> [op x46] GPCMD_GET_CONFIGURATION already exists.

Found, thank you.

Also op x5A GPCMD_MODE_SENSE_10 and page x2A GPMODE_CAPABILITIES_PAGE in
ide-cd.

Also op x5A MODE_SENSE_10 and anonymous x2a in sr.

> make DVD-RAM drives set CDC_MMC_RW as well
> and only check for that at open.

This part I still think I understand how to do.

> why then some things only work if you have ide-cd
> loaded, or if you use ide-scsi and sr ... a bad idea.

Aye.

Pat LaVarre