Re: [PATCH v2] pata_parport: add driver (PARIDE replacement)

[Hannes Reinecke]

On 1/21/23 23:53, Ondrej Zary wrote:
> The pata_parport is a libata-based replacement of the old PARIDE
> subsystem - driver for parallel port IDE devices.
> It uses the original paride low-level protocol drivers but does not
> need the high-level drivers (pd, pcd, pf, pt, pg). The IDE devices
> behind parallel port adapters are handled by the ATA layer.
>
> This will allow paride and its high-level drivers to be removed.
>
> Unfortunately, libata drivers cannot sleep so pata_parport claims
> parport before activating the ata host and keeps it claimed (and
> protocol connected) until the ata host is removed. This means that
> no devices can be chained (neither other pata_parport devices nor
> a printer).
>
> paride and pata_parport are mutually exclusive because the compiled
> protocol drivers are incompatible.
>
> Tested with:
>   - Imation SuperDisk LS-120 and HP C4381A (EPAT)
>   - Freecom Parallel CD (FRPW)
>   - Toshiba Mobile CD-RW 2793008 w/Freecom Parallel Cable rev.903 (FRIQ)
>   - Backpack CD-RW 222011 and CD-RW 19350 (BPCK6)
>
> The following bugs in low-level protocol drivers were found and will
> be fixed later:
>
> Note: EPP-32 mode is buggy in EPAT - and also in all other protocol
> drivers - they don't handle non-multiple-of-4 block transfers
> correctly. This causes problems with LS-120 drive.
> There is also another bug in EPAT: EPP modes don't work unless a 4-bit
> or 8-bit mode is used first (probably some initialization missing?).
> Once the device is initialized, EPP works until power cycle.
>
> So after device power on, you have to:
> echo "parport0 epat 0" >/sys/bus/pata_parport/new_device
> echo pata_parport.0 >/sys/bus/pata_parport/delete_device
> echo "parport0 epat 4" >/sys/bus/pata_parport/new_device
> (autoprobe will initialize correctly as it tries the slowest modes
> first but you'll get the broken EPP-32 mode)
>
> Note: EPP modes are buggy in FRPW, only modes 0 and 1 work.
> Signed-off-by: Ondrej Zary <linux@xxxxxxx>
> ---
>
> Changes in v2:
>   - keep device connected, remove disconnect timer
>
>   Documentation/admin-guide/blockdev/paride.rst |  52 ++
>   drivers/Makefile                              |   2 +-
>   drivers/ata/Kconfig                           |  14 +
>   drivers/ata/Makefile                          |   2 +
>   drivers/ata/pata_parport.c                    | 783 ++++++++++++++++++
>   drivers/block/paride/Kconfig                  |  32 +-
>   drivers/block/paride/paride.h                 |  13 +
>   include/linux/pata_parport.h                  | 106 +++
>   8 files changed, 987 insertions(+), 17 deletions(-)
>   create mode 100644 drivers/ata/pata_parport.c
>   create mode 100644 include/linux/pata_parport.h
Reviewed-by: Hannes Reinecke <hare@xxxxxxx>

Cheers,

Hannes
--
Dr. Hannes Reinecke		           Kernel Storage Architect
hare@xxxxxxx			                  +49 911 74053 688
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