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[PATCH v6 08/18] mtd: nand: denali: fix bank reset function to detect the number of chips

From Masahiro Yamada <yamada.masahiro@socionext.com>
Newsgroups linux.kernel
Subject [PATCH v6 08/18] mtd: nand: denali: fix bank reset function to detect the number of chips
Date 2017-06-13 07:10 +0200
Message-ID <tRMfv-3M1-5@gated-at.bofh.it> (permalink)
References <tRMfv-3M1-1@gated-at.bofh.it>
Organization linux.* mail to news gateway

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The nand_scan_ident() iterates over maxchips, and calls nand_reset()
for each.  This driver currently passes the maximum number of banks
(=chip selects) supported by the controller as maxchips.  So, maxchips
is typically 4 or 8.  Usually, less number of NAND chips are connected
to the controller.

This can be a problem for ONFi devices.  Now, this driver implements
->setup_data_interface() hook, so nand_setup_data_interface() issues
Set Features (0xEF) command, which waits until the chip returns R/B#
response.  If no chip there, we know it never happens, but the driver
still ends up with waiting for a long time.  It will finally bail-out
with timeout error and the driver will work with existing chips, but
unnecessary wait will give a bad user experience.

The denali_nand_reset() polls the INTR__RST_COMP and INTR__TIME_OUT
bits, but they are always set even if not NAND chip is connected to
that bank.  To know the chip existence, INTR__INT_ACT bit must be
checked; this flag is set only when R/B# is toggled.  Since the Reset
(0xFF) command toggles the R/B# pin, this can be used to know the
actual number of chips, and update denali->max_banks.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---

Boris mentioned this information can be retrieved from DT
(http://patchwork.ozlabs.org/patch/745118/), but I'd like to
take time for controller/chip decoupling.  I am tackling on
that, but not completed yet.

I believe this commit stands for denali_pci, at least I do not
know how to get the number of chips from PCI.


Changes in v6: None
Changes in v5: None
Changes in v4:
  - Reword commit-log

Changes in v3: None
Changes in v2:
  - Newly added

 drivers/mtd/nand/denali.c | 52 +++++++++++++++++++++--------------------------
 1 file changed, 23 insertions(+), 29 deletions(-)

diff --git a/drivers/mtd/nand/denali.c b/drivers/mtd/nand/denali.c
index 09a14fafa967..61a2ee9fb367 100644
--- a/drivers/mtd/nand/denali.c
+++ b/drivers/mtd/nand/denali.c
@@ -85,33 +85,6 @@ static void index_addr(struct denali_nand_info *denali,
 	iowrite32(data, denali->flash_mem + 0x10);
 }
 
-/* Reset the flash controller */
-static uint16_t denali_nand_reset(struct denali_nand_info *denali)
-{
-	int i;
-
-	for (i = 0; i < denali->max_banks; i++)
-		iowrite32(INTR__RST_COMP | INTR__TIME_OUT,
-		denali->flash_reg + INTR_STATUS(i));
-
-	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__TIME_OUT)
-			dev_dbg(denali->dev,
-			"NAND Reset operation timed out on bank %d\n", i);
-	}
-
-	for (i = 0; i < denali->max_banks; i++)
-		iowrite32(INTR__RST_COMP | INTR__TIME_OUT,
-			  denali->flash_reg + INTR_STATUS(i));
-
-	return PASS;
-}
-
 /*
  * Use the configuration feature register to determine the maximum number of
  * banks that the hardware supports.
@@ -998,7 +971,28 @@ static int denali_setup_data_interface(struct mtd_info *mtd, int chipnr,
 	return 0;
 }
 
-/* Initialization code to bring the device up to a known good state */
+static void denali_reset_banks(struct denali_nand_info *denali)
+{
+	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))
+			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)
 {
 	/*
@@ -1018,7 +1012,7 @@ 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_nand_reset(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);
-- 
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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