linux.git/drivers/scsi/atari_scsi.c, branch v4.9

atari_scsi: Allow can_queue to be increased for Falcon

2016-04-11T20:57:09+00:00

The benefit of limiting can_queue to 1 is that atari_scsi shares the
ST DMA chip more fairly with other drivers (e.g. falcon-ide).

Unfortunately, this can limit SCSI bus utilization. On systems without
IDE, atari_scsi should issue SCSI commands whenever it can arbitrate for
the bus. Make that possible by making can_queue configurable.

Signed-off-by: Finn Thain 
Reviewed-by: Hannes Reinecke 
Tested-by: Michael Schmitz 
Signed-off-by: Martin K. Petersen

atari_scsi: Set a reasonable default for cmd_per_lun

2016-04-11T20:57:09+00:00

This setting does not need to be conditional on Atari ST or TT.

Signed-off-by: Finn Thain 
Tested-by: Michael Schmitz 
Reviewed-by: Hannes Reinecke 
Signed-off-by: Martin K. Petersen

ncr5380: Remove disused atari_NCR5380.c core driver

2016-04-11T20:57:09+00:00

Now that atari_scsi and sun3_scsi have been converted to use the NCR5380.c
core driver, remove atari_NCR5380.c. Also remove the last vestiges of its
Tagged Command Queueing implementation from the wrapper drivers.

The TCQ support in atari_NCR5380.c is abandoned by this patch. It is not
merged into the remaining core driver because,

1) atari_scsi defines SUPPORT_TAGS but leaves FLAG_TAGGED_QUEUING disabled
by default, which indicates that it is mostly undesirable.

2) I'm told that it doesn't work correctly when enabled.

3) The algorithm does not make use of block layer tags which it will have
to do because scmd->tag is deprecated.

4) sun3_scsi doesn't define SUPPORT_TAGS at all, yet the the SUPPORT_TAGS
macro interacts with the CONFIG_SUN3 macro in 'interesting' ways.

5) Compile-time configuration with macros like SUPPORT_TAGS caused the
configuration space to explode, leading to untestable and unmaintainable
code that is too hard to reason about.

The merge_contiguous_buffers() code is also abandoned. This was unused
by sun3_scsi. Only atari_scsi used it and then only on TT, because only TT
supports scatter/gather. I suspect that the TT would work fine with
ENABLE_CLUSTERING instead. If someone can benchmark the difference then
perhaps the merge_contiguous_buffers() code can be be justified. Until
then we are better off without the extra complexity.

Signed-off-by: Finn Thain 
Reviewed-by: Hannes Reinecke 
Tested-by: Michael Schmitz 
Tested-by: Ondrej Zary 
Signed-off-by: Martin K. Petersen

atari_scsi: Adopt NCR5380.c core driver

2016-04-11T20:57:09+00:00

Add support for the Atari ST DMA chip to the NCR5380.c core driver.
This code is copied from atari_NCR5380.c.

Signed-off-by: Finn Thain 
Reviewed-by: Hannes Reinecke 
Tested-by: Michael Schmitz 
Tested-by: Ondrej Zary 
Signed-off-by: Martin K. Petersen

ncr5380: Adopt uniform DMA setup convention

2016-04-11T20:57:09+00:00

Standardize the DMA setup hooks so that the DMA implementation in
atari_NCR5380.c can be reconciled with pseudo DMA implementation in
NCR5380.c.

Calls to NCR5380_dma_recv_setup() and NCR5380_dma_send_setup() return
a negative value on failure, zero on PDMA transfer success and a positive
byte count for DMA setup success.

This convention is not entirely new, but is now applied consistently.

Also remove a pointless Status Register access: the *phase assignment is
redundant because after NCR5380_transfer_dma() returns control to
NCR5380_information_transfer(), that routine then returns control
to NCR5380_main(), which means *phase is dead.

Signed-off-by: Finn Thain 
Reviewed-by: Hannes Reinecke 
Tested-by: Michael Schmitz 
Tested-by: Ondrej Zary 
Signed-off-by: Martin K. Petersen

atari_NCR5380: Remove DMA_MIN_SIZE macro

2016-04-11T20:57:09+00:00

Only the atari_scsi and sun3_scsi drivers define DMA_MIN_SIZE.
Both drivers also define NCR5380_dma_xfer_len, which means
DMA_MIN_SIZE can be removed from the core driver.

This removes another discrepancy between the two core drivers.

Signed-off-by: Finn Thain 
Tested-by: Michael Schmitz 
Reviewed-by: Hannes Reinecke 
Signed-off-by: Martin K. Petersen

ncr5380: Remove REAL_DMA and REAL_DMA_POLL macros

2016-04-11T20:57:09+00:00

For the NCR5380.c core driver, these macros are never used.
If REAL_DMA were to be defined, compilation would fail.

For the atari_NCR5380.c core driver, REAL_DMA is always defined.

Hence these macros are pointless.

Signed-off-by: Finn Thain 
Reviewed-by: Hannes Reinecke 
Tested-by: Michael Schmitz 
Tested-by: Ondrej Zary 
Signed-off-by: Martin K. Petersen

atari_scsi, sun3_scsi: Remove global Scsi_Host pointer

2016-01-07T02:43:08+00:00

This refactoring removes two global Scsi_Host pointers. This
improves consistency with other ncr5380 drivers. Adopting the same
conventions as the other drivers makes them easier to read.

Signed-off-by: Finn Thain 
Reviewed-by: Hannes Reinecke 
Tested-by: Michael Schmitz 
Signed-off-by: Martin K. Petersen

ncr5380: Use standard list data structure

2016-01-07T02:43:07+00:00

The NCR5380 drivers have a home-spun linked list implementation for
scsi_cmnd structs that uses cmd->host_scribble as a 'next' pointer. Adopt
the standard list_head data structure and list operations instead. Remove
the eh_abort_handler rather than convert it. Doing the conversion would
only be churn because the existing EH handlers don't work and get replaced
in a subsequent patch.

Signed-off-by: Finn Thain 
Reviewed-by: Hannes Reinecke 
Tested-by: Ondrej Zary 
Tested-by: Michael Schmitz 
Signed-off-by: Martin K. Petersen

ncr5380: Remove command list debug code

2016-01-07T02:43:05+00:00

Some NCR5380 hosts offer a .show_info method to access the contents of
the various command list data structures from a procfs file. When NDEBUG
is set, the same information is sent to the console during EH.

The two core drivers, atari_NCR5380.c and NCR5380.c differ here. Because
it is just for debugging, the easiest way to fix the discrepancy is
simply remove this code.

The only remaining users of NCR5380_show_info() and NCR5380_write_info()
are drivers that define PSEUDO_DMA. The others have no use for the
.show_info method, so don't initialize it.

Signed-off-by: Finn Thain 
Reviewed-by: Hannes Reinecke 
Tested-by: Ondrej Zary 
Tested-by: Michael Schmitz 
Signed-off-by: Martin K. Petersen