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

From Masahiro Yamada <yamada.masahiro@socionext.com>
Newsgroups linux.kernel
Subject [PATCH v6 09/18] mtd: nand: denali: use interrupt instead of polling for bank reset
Date 2017-06-13 07:10 +0200
Message-ID <tRMfv-3M1-9@gated-at.bofh.it> (permalink)
References <tRMfv-3M1-1@gated-at.bofh.it>
Organization linux.* mail to news gateway

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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@socionext.com>
---

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(&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)
@@ -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

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Thread

[PATCH v6 00/18] mtd: nand: denali: Denali NAND IP patch bomb Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 02/18] mtd: nand: denali: remove unneeded find_valid_banks() Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 08/18] mtd: nand: denali: fix bank reset function to detect the number of chips Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 01/18] mtd: nand: denali: set NAND_ECC_CUSTOM_PAGE_ACCESS Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 16/18] mtd: nand: denali: use non-managed kmalloc() for DMA buffer Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 09/18] mtd: nand: denali: use interrupt instead of polling for bank reset Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 07/18] mtd: nand: denali: switch over to cmd_ctrl instead of cmdfunc Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 05/18] mtd: nand: denali: fix NAND_CMD_STATUS handling Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 18/18] mtd: nand: denali: avoid magic numbers and rename for clarification Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 15/18] mtd: nand: denali: skip driver internal bounce buffer when possible Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 03/18] mtd: nand: denali: handle timing parameters by setup_data_interface() Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 06/18] mtd: nand: denali: fix NAND_CMD_PARAM handling Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 13/18] mtd: nand: denali: fix raw and oob accessors for syndrome page layout Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 17/18] mtd: nand: denali: enable bad block table scan Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 11/18] mtd: nand: denali: merge struct nand_buf into struct denali_nand_info Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 14/18] mtd: nand: denali: support hardware-assisted erased page detection Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:10 +0200
  [PATCH v6 12/18] mtd: nand: denali: use flag instead of register macro for direction Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:20 +0200
  [PATCH v6 04/18] mtd: nand: denali: rework interrupt handling Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:20 +0200
  [PATCH v6 10/18] mtd: nand: denali: propagate page to helpers via function argument Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 07:20 +0200
  Re: [PATCH v6 00/18] mtd: nand: denali: Denali NAND IP patch bomb Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-06-13 09:10 +0200
    Re: [PATCH v6 00/18] mtd: nand: denali: Denali NAND IP patch bomb Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 10:10 +0200
      Re: [PATCH v6 00/18] mtd: nand: denali: Denali NAND IP patch bomb Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-06-13 10:30 +0200
    Re: [PATCH v6 00/18] mtd: nand: denali: Denali NAND IP patch bomb Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 10:20 +0200
      Re: [PATCH v6 00/18] mtd: nand: denali: Denali NAND IP patch bomb Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-06-13 10:40 +0200
        Re: [PATCH v6 00/18] mtd: nand: denali: Denali NAND IP patch bomb Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 11:00 +0200

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