On Monday 14 March 2022 00:19:30 Jens Axboe wrote: > On 3/13/22 1:15 PM, Ondrej Zary wrote: > > On Saturday 12 March 2022 15:44:15 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. > >> > >> paride and pata_parport are mutually exclusive because the compiled > >> protocol drivers are incompatible. > >> > >> Tested with Imation SuperDisk LS-120 and HP C4381A (both use EPAT > >> chip). > >> > >> 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) > > > > Found a bug - the same device can be registered multiple times. Fix > > will be in v2. But this revealed a bigger problem: pi_connect can > > sleep (uses parport_claim_or_block) and libata does not like that. Any > > ideas how to fix this? > > I think you'd need two things here: > > - The blk-mq queue should be registered with BLK_MQ_F_BLOCKING, which > will allow blocking off the queue_rq path. My knowledge about blk-mq is exactly zero. After grepping the code, I guess that BLK_MQ_F_BLOCKING should be used by the block device drivers - sd and sr? > - You need to look at making libata safe wrt calling ata_qc_issue() > outside the lock. Should probably be fine if you just gate that on > whether or not the queue was setup in blocking mode, as that doesn't > currently exist in libata. > -- Ondrej Zary
