[PATCH v6 09/18] mtd: nand: denali: use interrupt instead of polling for bank reset

[Masahiro Yamada]

The current bank reset implementation polls the INTR_STATUS register
until interested bits are set.  This is not good because:

- polling simply wastes time-slice of the thread

- The while() loop may continue eternally if no bit is set, for
  example, due to the controller problem.  The denali_wait_for_irq()
  uses wait_for_completion_timeout(), which is safer.

We can use interrupt by moving the denali_reset_bank() call below
the interrupt setup.

Signed-off-by: Masahiro Yamada 
---

Changes in v6: None
Changes in v5: None
Changes in v4: None
Changes in v3: None
Changes in v2:
  - Newly added

 drivers/mtd/nand/denali.c | 28 ++--
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/drivers/mtd/nand/denali.c b/drivers/mtd/nand/denali.c
index 61a2ee9fb367..7ae2fa65d601 100644
--- a/drivers/mtd/nand/denali.c
+++ b/drivers/mtd/nand/denali.c
@@ -973,24 +973,25 @@ static int denali_setup_data_interface(struct mtd_info 
*mtd, int chipnr,
 
 static void denali_reset_banks(struct denali_nand_info *denali)
 {
+   u32 irq_status;
int i;
 
-   denali_clear_irq_all(denali);
-
for (i = 0; i < denali->max_banks; i++) {
-   iowrite32(1 << i, denali->flash_reg + DEVICE_RESET);
-   while (!(ioread32(denali->flash_reg + INTR_STATUS(i)) &
-   (INTR__RST_COMP | INTR__TIME_OUT)))
-   cpu_relax();
-   if (!(ioread32(denali->flash_reg + INTR_STATUS(i)) &
- INTR__INT_ACT))
+   denali->flash_bank = i;
+
+   denali_reset_irq(denali);
+
+   iowrite32(DEVICE_RESET__BANK(i),
+ denali->flash_reg + DEVICE_RESET);
+
+   irq_status = denali_wait_for_irq(denali,
+   INTR__RST_COMP | INTR__INT_ACT | INTR__TIME_OUT);
+   if (!(irq_status & INTR__INT_ACT))
break;
}
 
dev_dbg(denali->dev, "%d chips connected\n", i);
denali->max_banks = i;
-
-   denali_clear_irq_all(denali);
 }
 
 static void denali_hw_init(struct denali_nand_info *denali)
@@ -1012,7 +1013,6 @@ static void denali_hw_init(struct denali_nand_info 
*denali)
denali->bbtskipbytes = ioread32(denali->flash_reg +
SPARE_AREA_SKIP_BYTES);
detect_max_banks(denali);
-   denali_reset_banks(denali);
iowrite32(0x0F, denali->flash_reg + RB_PIN_ENABLED);
iowrite32(CHIP_EN_DONT_CARE__FLAG,
denali->flash_reg + CHIP_ENABLE_DONT_CARE);
@@ -1130,9 +1130,6 @@ static void denali_drv_init(struct denali_nand_info 
*denali)
 * element that might be access shared data (interrupt status)
 */
spin_lock_init(>irq_lock);
-
-   /* indicate that MTD has not selected a valid bank yet */
-   denali->flash_bank = CHIP_SELECT_INVALID;
 }
 
 static int denali_multidev_fixup(struct denali_nand_info *denali)
@@ -1207,6 +1204,9 @@ int denali_init(struct denali_nand_info *denali)
}
 
denali_enable_irq(denali);
+   denali_reset_banks(denali);
+
+   denali->flash_bank = CHIP_SELECT_INVALID;
 
nand_set_flash_node(chip, denali->dev->of_node);
/* Fallback to the default name if DT did not give "label" property */
-- 
2.7.4

[PATCH v6 09/18] mtd: nand: denali: use interrupt instead of polling for bank reset

[Masahiro Yamada]

The current bank reset implementation polls the INTR_STATUS register
until interested bits are set.  This is not good because:

- polling simply wastes time-slice of the thread

- The while() loop may continue eternally if no bit is set, for
  example, due to the controller problem.  The denali_wait_for_irq()
  uses wait_for_completion_timeout(), which is safer.

We can use interrupt by moving the denali_reset_bank() call below
the interrupt setup.

Signed-off-by: Masahiro Yamada 
---

Changes in v6: None
Changes in v5: None
Changes in v4: None
Changes in v3: None
Changes in v2:
  - Newly added

 drivers/mtd/nand/denali.c | 28 ++--
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/drivers/mtd/nand/denali.c b/drivers/mtd/nand/denali.c
index 61a2ee9fb367..7ae2fa65d601 100644
--- a/drivers/mtd/nand/denali.c
+++ b/drivers/mtd/nand/denali.c
@@ -973,24 +973,25 @@ static int denali_setup_data_interface(struct mtd_info 
*mtd, int chipnr,
 
 static void denali_reset_banks(struct denali_nand_info *denali)
 {
+   u32 irq_status;
int i;
 
-   denali_clear_irq_all(denali);
-
for (i = 0; i < denali->max_banks; i++) {
-   iowrite32(1 << i, denali->flash_reg + DEVICE_RESET);
-   while (!(ioread32(denali->flash_reg + INTR_STATUS(i)) &
-   (INTR__RST_COMP | INTR__TIME_OUT)))
-   cpu_relax();
-   if (!(ioread32(denali->flash_reg + INTR_STATUS(i)) &
- INTR__INT_ACT))
+   denali->flash_bank = i;
+
+   denali_reset_irq(denali);
+
+   iowrite32(DEVICE_RESET__BANK(i),
+ denali->flash_reg + DEVICE_RESET);
+
+   irq_status = denali_wait_for_irq(denali,
+   INTR__RST_COMP | INTR__INT_ACT | INTR__TIME_OUT);
+   if (!(irq_status & INTR__INT_ACT))
break;
}
 
dev_dbg(denali->dev, "%d chips connected\n", i);
denali->max_banks = i;
-
-   denali_clear_irq_all(denali);
 }
 
 static void denali_hw_init(struct denali_nand_info *denali)
@@ -1012,7 +1013,6 @@ static void denali_hw_init(struct denali_nand_info 
*denali)
denali->bbtskipbytes = ioread32(denali->flash_reg +
SPARE_AREA_SKIP_BYTES);
detect_max_banks(denali);
-   denali_reset_banks(denali);
iowrite32(0x0F, denali->flash_reg + RB_PIN_ENABLED);
iowrite32(CHIP_EN_DONT_CARE__FLAG,
denali->flash_reg + CHIP_ENABLE_DONT_CARE);
@@ -1130,9 +1130,6 @@ static void denali_drv_init(struct denali_nand_info 
*denali)
 * element that might be access shared data (interrupt status)
 */
spin_lock_init(>irq_lock);
-
-   /* indicate that MTD has not selected a valid bank yet */
-   denali->flash_bank = CHIP_SELECT_INVALID;
 }
 
 static int denali_multidev_fixup(struct denali_nand_info *denali)
@@ -1207,6 +1204,9 @@ int denali_init(struct denali_nand_info *denali)
}
 
denali_enable_irq(denali);
+   denali_reset_banks(denali);
+
+   denali->flash_bank = CHIP_SELECT_INVALID;
 
nand_set_flash_node(chip, denali->dev->of_node);
/* Fallback to the default name if DT did not give "label" property */
-- 
2.7.4