[PATCH V2 01/13] pm80xx : Increase request sg length.

Deepak Ukey
2020-01-17T07:10:31Z

From: Peter Chang <dpf@google.com>

Increasing the per-request size maximum (max_sectors_kb) runs into
the per-device dma scatter gather list limit (max_segments) for
users of the io vector system calls (eg, readv and writev). This is
because the kernel combines io vectors into dma segments when
possible, but it doesn't work for our user because the vectors in the
buffer cache get scrambled.
This change bumps the advertised max scatter gather length to 528 to
cover 2M w/ x86's 4k pages and some extra for the user checksum.
It trims the size of some of the tables we don't care about and
exposes all of the command slots upstream to the scsi layer

Signed-off-by: Peter Chang <dpf@google.com>
Signed-off-by: Deepak Ukey <deepak.ukey@microchip.com>
Signed-off-by: Viswas G <Viswas.G@microchip.com>
Signed-off-by: Radha Ramachandran <radha@google.com>
Reported-by: kbuild test robot <lkp@intel.com>
---
drivers/scsi/pm8001/pm8001_defs.h | 5 +++--
drivers/scsi/pm8001/pm8001_init.c | 2 +-
2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/pm8001/pm8001_defs.h b/drivers/scsi/pm8001/pm8001_defs.h
index 48e0624ecc68..1c7f15fd69ce 100644
--- a/drivers/scsi/pm8001/pm8001_defs.h
+++ b/drivers/scsi/pm8001/pm8001_defs.h
@@ -75,7 +75,7 @@ enum port_type {
};

/* driver compile-time configuration */
-#define PM8001_MAX_CCB 512 /* max ccbs supported */
+#define PM8001_MAX_CCB 256 /* max ccbs supported */
#define PM8001_MPI_QUEUE 1024 /* maximum mpi queue entries */
#define PM8001_MAX_INB_NUM 1
#define PM8001_MAX_OUTB_NUM 1
@@ -99,7 +99,8 @@ enum port_type {
#define OB (CI + PM8001_MAX_SPCV_INB_NUM)
#define PI (OB + PM8001_MAX_SPCV_OUTB_NUM)
#define USI_MAX_MEMCNT (PI + PM8001_MAX_SPCV_OUTB_NUM)
-#define PM8001_MAX_DMA_SG SG_ALL
+#define CONFIG_SCSI_PM8001_MAX_DMA_SG 528
+#define PM8001_MAX_DMA_SG CONFIG_SCSI_PM8001_MAX_DMA_SG
enum memory_region_num {
AAP1 = 0x0, /* application acceleration processor */
IOP, /* IO processor */
diff --git a/drivers/scsi/pm8001/pm8001_init.c b/drivers/scsi/pm8001/pm8001_init.c
index ff618ad80ebd..3f1e755c52c6 100644
--- a/drivers/scsi/pm8001/pm8001_init.c
+++ b/drivers/scsi/pm8001/pm8001_init.c
@@ -95,7 +95,7 @@ static struct scsi_host_template pm8001_sht = {
.bios_param = sas_bios_param,
.can_queue = 1,
.this_id = -1,
- .sg_tablesize = SG_ALL,
+ .sg_tablesize = PM8001_MAX_DMA_SG,
.max_sectors = SCSI_DEFAULT_MAX_SECTORS,
.eh_device_reset_handler = sas_eh_device_reset_handler,
.eh_target_reset_handler = sas_eh_target_reset_handler,
--
2.16.3