BMC/Intel-BMC/linux.git/drivers/scsi/pas16.c, branch dev-4.6

ncr5380: Fix soft lockups

2016-01-07T02:43:09+00:00

Because of the rudimentary design of the chip, it is necessary to poll the SCSI bus signals during PIO and this tends to hog the CPU. The driver will accept new commands while others execute, and this causes a soft lockup because the workqueue item will not terminate until the issue queue is emptied. When exercising dmx3191d using sequential IO from dd, the driver is sent 512 KiB WRITE commands and 128 KiB READs. For a PIO transfer, the rate is is only about 300 KiB/s, so these are long-running commands. And although PDMA may run at several MiB/s, interrupts are disabled for the duration of the transfer. Fix the unresponsiveness and soft lockup issues by calling cond_resched() after each command is completed and by limiting max_sectors for drivers that don't implement real DMA. Signed-off-by: Finn Thain Reviewed-by: Hannes Reinecke Tested-by: Ondrej Zary 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: Fix and cleanup scsi_host_template initializers

2016-01-07T02:43:03+00:00

Add missing .module initializer. Use distinct .proc_name values for the g_NCR5380 and g_NCR5380_mmio modules. Remove pointless CAN_QUEUE and CMD_PER_LUN override macros. Cleanup whitespace and code style. Signed-off-by: Finn Thain Reviewed-by: Hannes Reinecke Tested-by: Ondrej Zary Tested-by: Michael Schmitz Signed-off-by: Martin K. Petersen

ncr5380: Cleanup #include directives

2016-01-07T02:43:02+00:00

Remove unused includes (stat.h, signal.h, proc_fs.h) and move includes needed by the core drivers into the common header (delay.h etc). 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 UNSAFE macro

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

Configuring core drivers using macros like this one prevents re-unifying the core driver forks, and prevents implementing the core driver as a library or a platform driver. The UNSAFE macro in particular is a poor workaround for the problem of interrupt latency. Releasing the locks complicates things because then we would have to handle the possibility of EH handler invocation during a PDMA transfer. The comments say that instead of using this macro, "you're going to be better off twiddling with transfersize". I agree. Remove this stuff. Signed-off-by: Finn Thain Reviewed-by: Hannes Reinecke Tested-by: Ondrej Zary Signed-off-by: Martin K. Petersen

ncr5380: Introduce unbound workqueue

2016-01-07T02:42:56+00:00

Allocate a work queue that will permit busy waiting and sleeping. This means NCR5380_init() can potentially fail, so add this error path. Signed-off-by: Finn Thain Reviewed-by: Hannes Reinecke Tested-by: Ondrej Zary Tested-by: Michael Schmitz Signed-off-by: Martin K. Petersen

ncr5380: Cleanup bogus {request,release}_region() calls

2016-01-07T02:42:55+00:00

Commit 8b801ead3d7a ("[ARM] rpc: update Acorn SCSI drivers to modern ecard interfaces") neglected to remove a request_region() call in cumana_1.c. Commit eda32612f7b2 ("[PATCH] give all LLDD driver a ->release method") in history/history.git added some pointless release_region() calls in dtc.c, pas16.c and t128.c. Fix these issues. Signed-off-by: Finn Thain Reviewed-by: Hannes Reinecke Signed-off-by: Martin K. Petersen

ncr5380: Split NCR5380_init() into two functions

2016-01-07T02:42:52+00:00

This patch splits the NCR5380_init() function into two parts, similar to the scheme used with atari_NCR5380.c. This avoids two problems. Firstly, NCR5380_init() may perform a bus reset, which would cause the chip to assert IRQ. The chip is unable to mask its bus reset interrupt. Drivers can't call request_irq() before calling NCR5380_init(), because initialization must happen before the interrupt handler executes. If driver initialization causes an interrupt it may be problematic on some platforms. To avoid that, first move the bus reset code into NCR5380_maybe_reset_bus(). Secondly, NCR5380_init() contains some board-specific interrupt setup code for the NCR53C400 that does not belong in the core driver. In moving this code, better not re-order interrupt initialization and bus reset. Again, the solution is to move the bus reset code into NCR5380_maybe_reset_bus(). Signed-off-by: Finn Thain Reviewed-by: Hannes Reinecke Tested-by: Ondrej Zary Signed-off-by: Martin K. Petersen

ncr5380: Remove NCR5380_local_declare and NCR5380_setup macros

2016-01-07T02:42:52+00:00

The NCR5380_local_declare and NCR5380_setup macros exist to define and initialize a particular local variable, to provide the address of the chip registers needed for the driver's implementation of its NCR5380_read/write register access macros. In cumana_1 and macscsi, these macros generate pointless code like this, struct Scsi_Host *_instance; _instance = instance; In pas16, the use of NCR5380_read/write in pas16_hw_detect() requires that the io_port local variable has been defined and initialized, but the NCR5380_local_declare and NCR5380_setup macros can't be used for that purpose because the Scsi_Host struct has not yet been instantiated. Moreover, these macros were removed from atari_NCR5380.c long ago and now they constitute yet another discrepancy between the two core driver forks. Remove these "optimizations". Signed-off-by: Finn Thain Reviewed-by: Hannes Reinecke Tested-by: Ondrej Zary Signed-off-by: Martin K. Petersen

ncr5380: Remove more pointless macros

2016-01-07T02:42:51+00:00

ASM macro is never defined. rtrc in pas16.c is not used. NCR5380_map_config, do_NCR5380_intr, do_t128_intr and do_pas16_intr are unused. NCR_NOT_SET harms readability. Remove them. Signed-off-by: Finn Thain Reviewed-by: Hannes Reinecke Tested-by: Ondrej Zary Signed-off-by: Martin K. Petersen