mtd: nand: denali: use interrupt instead of polling for bank reset

[Linux-MTD Mailing List]

Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=d49f5790278d18fd6b8e474397d9abfdf29a48f2
Commit:     d49f5790278d18fd6b8e474397d9abfdf29a48f2
Parent:     f486287d2372422d68768c88fe54e80a48aee8ec
Author:     Masahiro Yamada <yamada.masahiro at socionext.com>
AuthorDate: Tue Jun 13 22:45:41 2017 +0900
Committer:  Boris Brezillon <boris.brezillon at free-electrons.com>
CommitDate: Tue Jun 20 09:14:37 2017 +0200

    mtd: nand: denali: use interrupt instead of polling for bank reset
    
    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 <yamada.masahiro at socionext.com>
    Signed-off-by: Boris Brezillon <boris.brezillon at free-electrons.com>
---
 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 3169ba5..31d987d 100644
--- a/drivers/mtd/nand/denali.c
+++ b/drivers/mtd/nand/denali.c
@@ -1028,24 +1028,25 @@ 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)
@@ -1067,7 +1068,6 @@ 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);
@@ -1185,9 +1185,6 @@ static void denali_drv_init(struct denali_nand_info *denali)
 	 * element that might be access shared data (interrupt status)
 	 */
 	spin_lock_init(&denali->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)
@@ -1262,6 +1259,9 @@ 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 */