[PATCH 1/3] mxc_nand: set spare size and pages per block

[PATCH 1/3] mxc_nand: set spare size and pages per block

[John Ogness]

This patch sets the NFC registers for spare size and pages per block.

This patch is against the latest patches from Sascha Hauer.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
---
 drivers/mtd/nand/mxc_nand.c |   32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

Index: linux-2.6-454a740/drivers/mtd/nand/mxc_nand.c
===================================================================
--- linux-2.6-454a740.orig/drivers/mtd/nand/mxc_nand.c
+++ linux-2.6-454a740/drivers/mtd/nand/mxc_nand.c
@@ -68,6 +68,8 @@
 #define NFC_V1_V2_CONFIG1_RST		(1 << 6)
 #define NFC_V1_V2_CONFIG1_CE		(1 << 7)
 #define NFC_V1_V2_CONFIG1_ONE_CYCLE	(1 << 8)
+#define NFC_V1_V2_CONFIG1_PPB_SHIFT	9
+#define NFC_V1_V2_CONFIG1_PPB_MASK	0x3
 
 #define NFC_V1_V2_CONFIG2_INT		(1 << 15)
 
@@ -749,7 +751,37 @@ static void preset_v1_v2(struct mtd_info
 		host->eccsize = 1;
 	}
 
+	if (nfc_is_v21() && mtd->writesize) {
+		/* setup pages per block */
+		tmp &= ~(NFC_V1_V2_CONFIG1_PPB_MASK <<
+					NFC_V1_V2_CONFIG1_PPB_SHIFT);
+		switch (mtd->erasesize / mtd->writesize) {
+		case 32:
+			/* PPB set to 0 */
+			break;
+		case 64:
+			tmp |= 1 << NFC_V1_V2_CONFIG1_PPB_SHIFT;
+			break;
+		case 256:
+			tmp |= 3 << NFC_V1_V2_CONFIG1_PPB_SHIFT;
+			break;
+		default:
+			/* 128 (reset value) */
+			tmp |= 2 << NFC_V1_V2_CONFIG1_PPB_SHIFT;
+			break;
+		}
+	}
+
 	writew(tmp, NFC_V1_V2_CONFIG1);
+
+	if (nfc_is_v21()) {
+		/* configure spare size (in 16-bit units) */
+		tmp = readw(NFC_V1_V2_RSLTSPARE_AREA);
+		tmp &= ~0xff;
+		tmp |= host->spare_len >> 1;
+		writew(tmp, NFC_V1_V2_RSLTSPARE_AREA);
+	}
+
 	/* preset operation */
 
 	/* Unlock the internal RAM Buffer */

[PATCH 2/3] mxc_nand: remove unused variables

[John Ogness]

This patch removes some unused variable declarations.

This patch is against the latest patches from Sascha Hauer.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
---
 drivers/mtd/nand/mxc_nand.c |    2 --
 1 file changed, 2 deletions(-)

Index: linux-2.6-454a740/drivers/mtd/nand/mxc_nand.c
===================================================================
--- linux-2.6-454a740.orig/drivers/mtd/nand/mxc_nand.c
+++ linux-2.6-454a740/drivers/mtd/nand/mxc_nand.c
@@ -1221,8 +1221,6 @@ static int mxcnd_suspend(struct platform
 static int mxcnd_resume(struct platform_device *pdev)
 {
 	struct mtd_info *mtd = platform_get_drvdata(pdev);
-	struct nand_chip *nand_chip = mtd->priv;
-	struct mxc_nand_host *host = nand_chip->priv;
 	int ret = 0;
 
 	DEBUG(MTD_DEBUG_LEVEL0, "MXC_ND : NAND resume\n");

[PATCH 3/3] mxc_nand: mask instead of disabling (i.MX21 as exception)

[John Ogness]

This patch reverts the driver to using the NFC interrupt mask rather
than enabling/disabling the system interrupt. This cleans up the
driver so that it doesn't rely on interrupts being disabled
within the interrupt handler. The required workaround for the i.MX21
has been encapsulated using the nfc_avoid_masking macro.

This patch is against the latest patches from Sascha Hauer.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
---
 drivers/mtd/nand/mxc_nand.c |  138 ++++++++++++++++++++++++++--------
 1 file changed, 109 insertions(+), 29 deletions(-)

Index: linux-2.6-454a740/drivers/mtd/nand/mxc_nand.c
===================================================================
--- linux-2.6-454a740.orig/drivers/mtd/nand/mxc_nand.c
+++ linux-2.6-454a740/drivers/mtd/nand/mxc_nand.c
@@ -30,6 +30,8 @@
 #include <linux/clk.h>
 #include <linux/err.h>
 #include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/completion.h>
 
 #include <asm/mach/flash.h>
 #include <mach/mxc_nand.h>
@@ -42,6 +44,13 @@
 #define nfc_is_v3_2()		cpu_is_mx51()
 #define nfc_is_v3()		nfc_is_v3_2()
 
+/* It has been observed that the i.MX21 cannot read its CONFIG2:INT bit
+ * if interrupts are masked (CONFIG1:INT_MSK is set). To handle this, the
+ * driver can enable/disable the irq line rather than simply masking the
+ * interrupts. The nfc_avoid_masking() macro identifies the systems that
+ * should use this workaround. */
+#define nfc_avoid_masking()    (cpu_is_mx21())
+
 /* Addresses for NFC registers */
 #define NFC_V1_V2_BUF_SIZE		(host->regs + 0x00)
 #define NFC_V1_V2_BUF_ADDR		(host->regs + 0x04)
@@ -151,7 +160,7 @@ struct mxc_nand_host {
 	int			irq;
 	int			eccsize;
 
-	wait_queue_head_t	irq_waitq;
+	struct completion	op_completion;
 
 	uint8_t			*data_buf;
 	unsigned int		buf_start;
@@ -163,7 +172,10 @@ struct mxc_nand_host {
 	void			(*send_page)(struct mtd_info *, unsigned int);
 	void			(*send_read_id)(struct mxc_nand_host *);
 	uint16_t		(*get_dev_status)(struct mxc_nand_host *);
-	int			(*check_int)(struct mxc_nand_host *);
+	int			(*isset_int)(struct mxc_nand_host *);
+	void			(*ack_int)(struct mxc_nand_host *);
+	void			(*mask_int)(struct mxc_nand_host *);
+	void			(*unmask_int)(struct mxc_nand_host *);
 };
 
 /* OOB placement block for use with hardware ecc generation */
@@ -216,38 +228,74 @@ static irqreturn_t mxc_nfc_irq(int irq, 
 {
 	struct mxc_nand_host *host = dev_id;
 
-	disable_irq_nosync(irq);
-
-	wake_up(&host->irq_waitq);
+	/* If NFC_INT is not set, we have a spurious interrupt! */
+	if (!host->isset_int(host))
+		return IRQ_NONE;
+
+	/* Even with nfc_avoid_masking() we mask the interrupt
+	 * here to avoid an interrupt flood until the irq line
+	 * is disabled by the driver thread. */
+	host->mask_int(host);
+
+	/* Notify the driver thread that an interrupt has occurred.
+	 * The driver thread will clear the interrupt. */
+	complete(&host->op_completion);
 
 	return IRQ_HANDLED;
 }
 
-static int check_int_v3(struct mxc_nand_host *host)
+static int isset_int_v3(struct mxc_nand_host *host)
 {
-	uint32_t tmp;
-
-	tmp = readl(NFC_V3_IPC);
-	if (!(tmp & NFC_V3_IPC_INT))
-		return 0;
+	uint32_t tmp = readl(NFC_V3_IPC);
+	return (tmp & NFC_V3_IPC_INT);
+}
 
+static void ack_int_v3(struct mxc_nand_host *host)
+{
+	uint32_t tmp = readl(NFC_V3_IPC);
 	tmp &= ~NFC_V3_IPC_INT;
 	writel(tmp, NFC_V3_IPC);
+}
 
-	return 1;
+static void mask_int_v3(struct mxc_nand_host *host)
+{
+	uint32_t tmp = readl(NFC_V3_CONFIG2);
+	tmp |= NFC_V3_CONFIG2_INT_MSK;
+	writel(tmp, NFC_V3_CONFIG2);
 }
 
-static int check_int_v1_v2(struct mxc_nand_host *host)
+static void unmask_int_v3(struct mxc_nand_host *host)
 {
-	uint32_t tmp;
+	uint32_t tmp = readl(NFC_V3_CONFIG2);
+	tmp &= ~NFC_V3_CONFIG2_INT_MSK;
+	writel(tmp, NFC_V3_CONFIG2);
+}
 
-	tmp = readw(NFC_V1_V2_CONFIG2);
-	if (!(tmp & NFC_V1_V2_CONFIG2_INT))
-		return 0;
+static int isset_int_v1_v2(struct mxc_nand_host *host)
+{
+	uint16_t tmp = readw(NFC_V1_V2_CONFIG2);
+	return (tmp & NFC_V1_V2_CONFIG2_INT);
+}
 
-	writew(tmp & ~NFC_V1_V2_CONFIG2_INT, NFC_V1_V2_CONFIG2);
+static void ack_int_v1_v2(struct mxc_nand_host *host)
+{
+	uint16_t tmp = readw(NFC_V1_V2_CONFIG2);
+	tmp &= ~NFC_V1_V2_CONFIG2_INT;
+	writew(tmp, NFC_V1_V2_CONFIG2);
+}
 
-	return 1;
+static void mask_int_v1_v2(struct mxc_nand_host *host)
+{
+	uint16_t tmp = readw(NFC_V1_V2_CONFIG1);
+	tmp |= NFC_V1_V2_CONFIG1_INT_MSK;
+	writew(tmp, NFC_V1_V2_CONFIG1);
+}
+
+static void unmask_int_v1_v2(struct mxc_nand_host *host)
+{
+	uint16_t tmp = readw(NFC_V1_V2_CONFIG1);
+	tmp &= ~NFC_V1_V2_CONFIG1_INT_MSK;
+	writew(tmp, NFC_V1_V2_CONFIG1);
 }
 
 /* This function polls the NANDFC to wait for the basic operation to
@@ -258,16 +306,33 @@ static void wait_op_done(struct mxc_nand
 	int max_retries = 8000;
 
 	if (useirq) {
-		if (!host->check_int(host)) {
-
-			enable_irq(host->irq);
+		if (!host->isset_int(host)) {
+			INIT_COMPLETION(host->op_completion);
 
-			wait_event(host->irq_waitq, host->check_int(host));
+			if (nfc_avoid_masking())
+				enable_irq(host->irq);
+			else
+				host->unmask_int(host);
+
+			/* wait for the interrupt */
+			wait_for_completion(&host->op_completion);
+
+			/* The irq handler masked the interrupt
+			 * and expects us to ack the interrupt. */
+
+			if (nfc_avoid_masking()) {
+				disable_irq(host->irq);
+				host->unmask_int(host);
+			}
 		}
+
+		host->ack_int(host);
 	} else {
 		while (max_retries-- > 0) {
-			if (host->check_int(host))
+			if (host->isset_int(host)) {
+				host->ack_int(host);
 				break;
+			}
 
 			udelay(1);
 		}
@@ -735,7 +800,6 @@ static void preset_v1_v2(struct mtd_info
 
 	/* enable interrupt, disable spare enable */
 	tmp = readw(NFC_V1_V2_CONFIG1);
-	tmp &= ~NFC_V1_V2_CONFIG1_INT_MSK;
 	tmp &= ~NFC_V1_V2_CONFIG1_SP_EN;
 	if (nand_chip->ecc.mode == NAND_ECC_HW) {
 		tmp |= NFC_V1_V2_CONFIG1_ECC_EN;
@@ -828,6 +892,9 @@ static void preset_v3(struct mtd_info *m
 		NFC_V3_CONFIG2_ST_CMD(0x70) |
 		NFC_V3_CONFIG2_NUM_ADDR_PHASE0;
 
+	if (!nfc_avoid_masking())
+		config2 |= NFC_V3_CONFIG2_INT_MSK;
+
 	if (chip->ecc.mode == NAND_ECC_HW)
 		config2 |= NFC_V3_CONFIG2_ECC_EN;
 
@@ -1050,7 +1117,10 @@ static int __init mxcnd_probe(struct pla
 		host->send_page = send_page_v1_v2;
 		host->send_read_id = send_read_id_v1_v2;
 		host->get_dev_status = get_dev_status_v1_v2;
-		host->check_int = check_int_v1_v2;
+		host->isset_int = isset_int_v1_v2;
+		host->ack_int = ack_int_v1_v2;
+		host->mask_int = mask_int_v1_v2;
+		host->unmask_int = unmask_int_v1_v2;
 	}
 
 	if (nfc_is_v21()) {
@@ -1087,7 +1157,10 @@ static int __init mxcnd_probe(struct pla
 		host->send_addr = send_addr_v3;
 		host->send_page = send_page_v3;
 		host->send_read_id = send_read_id_v3;
-		host->check_int = check_int_v3;
+		host->isset_int = isset_int_v3;
+		host->ack_int = ack_int_v3;
+		host->mask_int = mask_int_v3;
+		host->unmask_int = unmask_int_v3;
 		host->get_dev_status = get_dev_status_v3;
 		oob_smallpage = &nandv2_hw_eccoob_smallpage;
 		oob_largepage = &nandv2_hw_eccoob_largepage;
@@ -1120,11 +1193,18 @@ static int __init mxcnd_probe(struct pla
 		this->options |= NAND_USE_FLASH_BBT;
 	}
 
-	init_waitqueue_head(&host->irq_waitq);
+	init_completion(&host->op_completion);
 
 	host->irq = platform_get_irq(pdev, 0);
 
-	err = request_irq(host->irq, mxc_nfc_irq, IRQF_DISABLED, DRIVER_NAME, host);
+	if (nfc_avoid_masking()) {
+		set_irq_flags(host->irq, IRQF_VALID | IRQF_NOAUTOEN);
+		host->unmask_int(host);
+	} else {
+		host->mask_int(host);
+	}
+
+	err = request_irq(host->irq, mxc_nfc_irq, 0, DRIVER_NAME, host);
 	if (err)
 		goto eirq;
 

[PATCH 1/3] mxc_nand: set spare size and pages per block

[Sascha Hauer]

Hi John,

Sorry, last time I sent only up to 09/12, so the patches I explicitely
mentioned to solve the things from your previous series were missing.
I just sent them. My versions of the patches differ slightly. For this
patch I decided to initialize every bit in NFC_V1_V2_CONFIG1 from
scratch so that we do not depend on any reset or bootloader values.
I think this is cleaner so I propose that we use my version of the
patch.

Sascha

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

[PATCH 1/3] mxc_nand: set spare size and pages per block

[John Ogness]

On 2010-08-10, Sascha Hauer <s.hauer@pengutronix.de> wrote:
> Sorry, last time I sent only up to 09/12, so the patches I explicitely
> mentioned to solve the things from your previous series were missing.
> I just sent them. My versions of the patches differ slightly.

Your version allows a small window between request_irq() and
irq_control() where on the i.MX21 there is a possibility of the
interrupts being disabled twice. Namely, if an interrupt occurs before
irq_control() has had a chance to disable it. IMHO it would be better to
call:

    set_irq_flags(host->irq, IRQF_VALID | IRQF_NOAUTOEN);

for the i.MX21 before requesting the irq. This closes the window.

For non-i.MX21 this window also exists, but since in that situation the
irq hander simply unnecessarily sets a bit, it is not so dramatic. By
masking the interrupt before requesting the irq, the windows is also
closed for non-i.MX21.

> For this patch I decided to initialize every bit in NFC_V1_V2_CONFIG1
> from scratch so that we do not depend on any reset or bootloader
> values.  I think this is cleaner so I propose that we use my version
> of the patch.

I agree that initializing all the bits is better. But you need to set
the mask as well. Your latest patches clear the mask when initializing
V1_V2_CONFIG1 and V3_CONFIG2. For non-i.MX21 the mask should always be
set except when explicitly waiting for an interrupt in wait_op_done().

All the patches (01-12) were tested on an i.MX35 with 16-bit NAND and
work as expected. My only recommendations would be to close the window
at request_irq() and also include the following patch to set the mask
during preset().

Signed-off-by: John Ogness <john.ogness@linutronix.de>
---
 drivers/mtd/nand/mxc_nand.c |    3 +++
 1 file changed, 3 insertions(+)

Index: linux-2.6-454a740/drivers/mtd/nand/mxc_nand.c
===================================================================
--- linux-2.6-454a740.orig/drivers/mtd/nand/mxc_nand.c
+++ linux-2.6-454a740/drivers/mtd/nand/mxc_nand.c
@@ -788,6 +788,8 @@ static void preset_v1_v2(struct mtd_info
 
 	if (nfc_is_v21())
 		config1 |= NFC_V2_CONFIG1_FP_INT;
+	else
+		config1 |= NFC_V1_V2_CONFIG1_INT_MSK;
 
 	if (nfc_is_v21() && mtd->writesize) {
 		uint16_t pages_per_block = mtd->erasesize / mtd->writesize;
@@ -846,6 +848,7 @@ static void preset_v3(struct mtd_info *m
 		NFC_V3_CONFIG2_2CMD_PHASES |
 		NFC_V3_CONFIG2_SPAS(mtd->oobsize >> 1) |
 		NFC_V3_CONFIG2_ST_CMD(0x70) |
+		NFC_V3_CONFIG2_INT_MSK |
 		NFC_V3_CONFIG2_NUM_ADDR_PHASE0;
 
 	if (chip->ecc.mode == NAND_ECC_HW)

[PATCH 1/3] mxc_nand: set spare size and pages per block

[John Ogness]

On 2010-08-10, John Ogness <john.ogness@linutronix.de> wrote:
>> For this patch I decided to initialize every bit in NFC_V1_V2_CONFIG1
>> from scratch so that we do not depend on any reset or bootloader
>> values.  I think this is cleaner so I propose that we use my version
>> of the patch.
>
> I agree that initializing all the bits is better. But you need to set
> the mask as well. Your latest patches clear the mask when initializing
> V1_V2_CONFIG1 and V3_CONFIG2. For non-i.MX21 the mask should always be
> set except when explicitly waiting for an interrupt in wait_op_done().

Sorry, that last patch was crap. It wasn't setting the mask for v1/v2. I
should have noticed it sooner because without the mask an extra
interrupt is visible during boot. Here is the correct patch to fix the
masking issue.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
---
 drivers/mtd/nand/mxc_nand.c |    4 ++++
 1 file changed, 4 insertions(+)

Index: linux-2.6-454a740/drivers/mtd/nand/mxc_nand.c
===================================================================
--- linux-2.6-454a740.orig/drivers/mtd/nand/mxc_nand.c
+++ linux-2.6-454a740/drivers/mtd/nand/mxc_nand.c
@@ -789,6 +789,9 @@ static void preset_v1_v2(struct mtd_info
 	if (nfc_is_v21())
 		config1 |= NFC_V2_CONFIG1_FP_INT;
 
+	if (!cpu_is_mx21())
+		config1 |= NFC_V1_V2_CONFIG1_INT_MSK;
+
 	if (nfc_is_v21() && mtd->writesize) {
 		uint16_t pages_per_block = mtd->erasesize / mtd->writesize;
 
@@ -846,6 +849,7 @@ static void preset_v3(struct mtd_info *m
 		NFC_V3_CONFIG2_2CMD_PHASES |
 		NFC_V3_CONFIG2_SPAS(mtd->oobsize >> 1) |
 		NFC_V3_CONFIG2_ST_CMD(0x70) |
+		NFC_V3_CONFIG2_INT_MSK |
 		NFC_V3_CONFIG2_NUM_ADDR_PHASE0;
 
 	if (chip->ecc.mode == NAND_ECC_HW)

[PATCH 1/3] mxc_nand: set spare size and pages per block

[Sascha Hauer]

On Tue, Aug 10, 2010 at 04:31:40PM +0200, John Ogness wrote:
> On 2010-08-10, Sascha Hauer <s.hauer@pengutronix.de> wrote:
> > Sorry, last time I sent only up to 09/12, so the patches I explicitely
> > mentioned to solve the things from your previous series were missing.
> > I just sent them. My versions of the patches differ slightly.
> 
> Your version allows a small window between request_irq() and
> irq_control() where on the i.MX21 there is a possibility of the
> interrupts being disabled twice. Namely, if an interrupt occurs before
> irq_control() has had a chance to disable it. IMHO it would be better to
> call:
> 
>     set_irq_flags(host->irq, IRQF_VALID | IRQF_NOAUTOEN);
> 
> for the i.MX21 before requesting the irq. This closes the window.

IIRC it is not allowed to call set_irq_flags before request_irq. We are
changing a resource we do not own yet.
I think the worst thing that could happen without this change is that we
get an interrupt after request_irq.
Alternatively we could set the interrupt mask bit before requesting the
irq.

Sascha

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

[PATCH 1/3] mxc_nand: set spare size and pages per block

[John Ogness]

On 2010-08-11, Sascha Hauer <s.hauer@pengutronix.de> wrote:
>> Your version allows a small window between request_irq() and
>> irq_control() where on the i.MX21 there is a possibility of the
>> interrupts being disabled twice. Namely, if an interrupt occurs
>> before irq_control() has had a chance to disable it. IMHO it would be
>> better to call:
>> 
>>     set_irq_flags(host->irq, IRQF_VALID | IRQF_NOAUTOEN);
>> 
>> for the i.MX21 before requesting the irq. This closes the window.
>
> IIRC it is not allowed to call set_irq_flags before request_irq. We
> are changing a resource we do not own yet.

Normally, yes. But the only way the IRQF_NOAUTOEN flag can ever be
useful is if set_irq_flags() is called before request_irq().

> I think the worst thing that could happen without this change is that
> we get an interrupt after request_irq.

Yes. And this causes a problem on the i.MX21 because the interrupt
handler will disable the interrupts. The irq_control() after
request_irq() will _also_ disable the interrupts. This means the
interrupts are disabled twice, which causes some issues on an RT kernel.

> Alternatively we could set the interrupt mask bit before requesting
> the irq.

Yes. This would be best. But for the i.MX21 it is important that the
interrupts are unmasked after irq_control() has disabled the interrupts.

John Ogness

[PATCH 1/3] mxc_nand: set spare size and pages per block

[Sascha Hauer]

On Wed, Aug 11, 2010 at 03:16:34PM +0200, John Ogness wrote:
> On 2010-08-11, Sascha Hauer <s.hauer@pengutronix.de> wrote:
> >> Your version allows a small window between request_irq() and
> >> irq_control() where on the i.MX21 there is a possibility of the
> >> interrupts being disabled twice. Namely, if an interrupt occurs
> >> before irq_control() has had a chance to disable it. IMHO it would be
> >> better to call:
> >> 
> >>     set_irq_flags(host->irq, IRQF_VALID | IRQF_NOAUTOEN);
> >> 
> >> for the i.MX21 before requesting the irq. This closes the window.
> >
> > IIRC it is not allowed to call set_irq_flags before request_irq. We
> > are changing a resource we do not own yet.
> 
> Normally, yes. But the only way the IRQF_NOAUTOEN flag can ever be
> useful is if set_irq_flags() is called before request_irq().
> 
> > I think the worst thing that could happen without this change is that
> > we get an interrupt after request_irq.
> 
> Yes. And this causes a problem on the i.MX21 because the interrupt
> handler will disable the interrupts. The irq_control() after
> request_irq() will _also_ disable the interrupts. This means the
> interrupts are disabled twice, which causes some issues on an RT kernel.
> 
> > Alternatively we could set the interrupt mask bit before requesting
> > the irq.
> 
> Yes. This would be best. But for the i.MX21 it is important that the
> interrupts are unmasked after irq_control() has disabled the interrupts.

Ok, I'll update the patches to use this approach.

Sascha

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
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[PATCH 1/3] mxc_nand: set spare size and pages per block

[Sascha Hauer]

On Wed, Aug 11, 2010 at 03:16:34PM +0200, John Ogness wrote:
> On 2010-08-11, Sascha Hauer <s.hauer@pengutronix.de> wrote:
> >> Your version allows a small window between request_irq() and
> >> irq_control() where on the i.MX21 there is a possibility of the
> >> interrupts being disabled twice. Namely, if an interrupt occurs
> >> before irq_control() has had a chance to disable it. IMHO it would be
> >> better to call:
> >> 
> >>     set_irq_flags(host->irq, IRQF_VALID | IRQF_NOAUTOEN);
> >> 
> >> for the i.MX21 before requesting the irq. This closes the window.
> >
> > IIRC it is not allowed to call set_irq_flags before request_irq. We
> > are changing a resource we do not own yet.
> 
> Normally, yes. But the only way the IRQF_NOAUTOEN flag can ever be
> useful is if set_irq_flags() is called before request_irq().
> 
> > I think the worst thing that could happen without this change is that
> > we get an interrupt after request_irq.
> 
> Yes. And this causes a problem on the i.MX21 because the interrupt
> handler will disable the interrupts. The irq_control() after
> request_irq() will _also_ disable the interrupts. This means the
> interrupts are disabled twice, which causes some issues on an RT kernel.
> 
> > Alternatively we could set the interrupt mask bit before requesting
> > the irq.
> 
> Yes. This would be best. But for the i.MX21 it is important that the
> interrupts are unmasked after irq_control() has disabled the interrupts.

Ok, here is an updated version of this patch

Sascha

commit 3a411e6c690654f78bea93dd8cdb14c27ba418a5
Author: Sascha Hauer <s.hauer@pengutronix.de>
Date:   Mon Aug 9 14:21:00 2010 +0200

    mxc_nand: do not depend on disabling the irq in the interrupt handler
    
    This patch reverts the driver to enabling/disabling the NFC interrupt
    mask rather than enabling/disabling the system interrupt. This cleans
    up the driver so that it doesn't rely on interrupts being disabled
    within the interrupt handler.
    For i.MX21 we keep the current behaviour, that is calling
    enable_irq/disable_irq_nosync to enable/disable interrupts.
    This patch is based on earlier work by John Ogness.
    
    Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

diff --git a/drivers/mtd/nand/mxc_nand.c b/drivers/mtd/nand/mxc_nand.c
index d58214b..c1a3d04 100644
--- a/drivers/mtd/nand/mxc_nand.c
+++ b/drivers/mtd/nand/mxc_nand.c
@@ -30,6 +30,8 @@
 #include <linux/clk.h>
 #include <linux/err.h>
 #include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/completion.h>
 
 #include <asm/mach/flash.h>
 #include <mach/mxc_nand.h>
@@ -149,7 +151,7 @@ struct mxc_nand_host {
 	int			irq;
 	int			eccsize;
 
-	wait_queue_head_t	irq_waitq;
+	struct completion	op_completion;
 
 	uint8_t			*data_buf;
 	unsigned int		buf_start;
@@ -162,6 +164,7 @@ struct mxc_nand_host {
 	void			(*send_read_id)(struct mxc_nand_host *);
 	uint16_t		(*get_dev_status)(struct mxc_nand_host *);
 	int			(*check_int)(struct mxc_nand_host *);
+	void			(*irq_control)(struct mxc_nand_host *, int);
 };
 
 /* OOB placement block for use with hardware ecc generation */
@@ -214,9 +217,12 @@ static irqreturn_t mxc_nfc_irq(int irq, void *dev_id)
 {
 	struct mxc_nand_host *host = dev_id;
 
-	disable_irq_nosync(irq);
+	if (!host->check_int(host))
+		return IRQ_NONE;
 
-	wake_up(&host->irq_waitq);
+	host->irq_control(host, 0);
+
+	complete(&host->op_completion);
 
 	return IRQ_HANDLED;
 }
@@ -243,11 +249,54 @@ static int check_int_v1_v2(struct mxc_nand_host *host)
 	if (!(tmp & NFC_V1_V2_CONFIG2_INT))
 		return 0;
 
-	writew(tmp & ~NFC_V1_V2_CONFIG2_INT, NFC_V1_V2_CONFIG2);
+	if (!cpu_is_mx21())
+		writew(tmp & ~NFC_V1_V2_CONFIG2_INT, NFC_V1_V2_CONFIG2);
 
 	return 1;
 }
 
+/*
+ * It has been observed that the i.MX21 cannot read the CONFIG2:INT bit
+ * if interrupts are masked (CONFIG1:INT_MSK is set). To handle this, the
+ * driver can enable/disable the irq line rather than simply masking the
+ * interrupts.
+ */
+static void irq_control_mx21(struct mxc_nand_host *host, int activate)
+{
+	if (activate)
+		enable_irq(host->irq);
+	else
+		disable_irq_nosync(host->irq);
+}
+
+static void irq_control_v1_v2(struct mxc_nand_host *host, int activate)
+{
+	uint16_t tmp;
+
+	tmp = readw(NFC_V1_V2_CONFIG1);
+
+	if (activate)
+		tmp &= ~NFC_V1_V2_CONFIG1_INT_MSK;
+	else
+		tmp |= NFC_V1_V2_CONFIG1_INT_MSK;
+
+	writew(tmp, NFC_V1_V2_CONFIG1);
+}
+
+static void irq_control_v3(struct mxc_nand_host *host, int activate)
+{
+	uint32_t tmp;
+
+	tmp = readl(NFC_V3_CONFIG2);
+
+	if (activate)
+		tmp &= ~NFC_V3_CONFIG2_INT_MSK;
+	else
+		tmp |= NFC_V3_CONFIG2_INT_MSK;
+
+	writel(tmp, NFC_V3_CONFIG2);
+}
+
 /* This function polls the NANDFC to wait for the basic operation to
  * complete by checking the INT bit of config2 register.
  */
@@ -257,10 +306,9 @@ static void wait_op_done(struct mxc_nand_host *host, int useirq)
 
 	if (useirq) {
 		if (!host->check_int(host)) {
-
-			enable_irq(host->irq);
-
-			wait_event(host->irq_waitq, host->check_int(host));
+			INIT_COMPLETION(host->op_completion);
+			host->irq_control(host, 1);
+			wait_for_completion(&host->op_completion);
 		}
 	} else {
 		while (max_retries-- > 0) {
@@ -731,9 +779,8 @@ static void preset_v1_v2(struct mtd_info *mtd)
 	struct mxc_nand_host *host = nand_chip->priv;
 	uint16_t tmp;
 
-	/* enable interrupt, disable spare enable */
+	/* disable spare enable */
 	tmp = readw(NFC_V1_V2_CONFIG1);
-	tmp &= ~NFC_V1_V2_CONFIG1_INT_MSK;
 	tmp &= ~NFC_V1_V2_CONFIG1_SP_EN;
 	if (nand_chip->ecc.mode == NAND_ECC_HW) {
 		tmp |= NFC_V1_V2_CONFIG1_ECC_EN;
@@ -1020,6 +1067,10 @@ static int __init mxcnd_probe(struct platform_device *pdev)
 		host->send_read_id = send_read_id_v1_v2;
 		host->get_dev_status = get_dev_status_v1_v2;
 		host->check_int = check_int_v1_v2;
+		if (cpu_is_mx21())
+			host->irq_control = irq_control_mx21;
+		else
+			host->irq_control = irq_control_v1_v2;
 	}
 
 	if (nfc_is_v21()) {
@@ -1058,6 +1109,7 @@ static int __init mxcnd_probe(struct platform_device *pdev)
 		host->send_read_id = send_read_id_v3;
 		host->check_int = check_int_v3;
 		host->get_dev_status = get_dev_status_v3;
+		host->irq_control = irq_control_v3;
 		oob_smallpage = &nandv2_hw_eccoob_smallpage;
 		oob_largepage = &nandv2_hw_eccoob_largepage;
 	} else
@@ -1089,14 +1141,34 @@ static int __init mxcnd_probe(struct platform_device *pdev)
 		this->options |= NAND_USE_FLASH_BBT;
 	}
 
-	init_waitqueue_head(&host->irq_waitq);
+	init_completion(&host->op_completion);
 
 	host->irq = platform_get_irq(pdev, 0);
 
+	/*
+	 * mask the interrupt. For i.MX21 explicitely call
+	 * irq_control_v1_v2 to use the mask bit. We can't call
+	 * disable_irq_nosync() for an interrupt we do not own yet.
+	 */
+	if (cpu_is_mx21())
+		irq_control_v1_v2(host, 0);
+	else
+		host->irq_control(host, 0);
+
 	err = request_irq(host->irq, mxc_nfc_irq, IRQF_DISABLED, DRIVER_NAME, host);
 	if (err)
 		goto eirq;
 
+	host->irq_control(host, 0);
+
+	/*
+	 * Now that the interrupt is disabled make sure the interrupt
+	 * mask bit is cleared on i.MX21. Otherwise we can't read
+	 * the interrupt status bit on this machine.
+	 */
+	if (cpu_is_mx21())
+		irq_control_v1_v2(host, 1);
+
 	/* first scan to find the device and get the page size */
 	if (nand_scan_ident(mtd, 1, NULL)) {
 		err = -ENXIO;

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

[PATCH 1/3] mxc_nand: set spare size and pages per block

[John Ogness]

On 2010-08-16, Sascha Hauer <s.hauer@pengutronix.de> wrote:
> Ok, here is an updated version of this patch
>
> Sascha
>
> commit 3a411e6c690654f78bea93dd8cdb14c27ba418a5
> Author: Sascha Hauer <s.hauer@pengutronix.de>
> Date:   Mon Aug 9 14:21:00 2010 +0200
>
>     mxc_nand: do not depend on disabling the irq in the interrupt handler
>     
>     This patch reverts the driver to enabling/disabling the NFC interrupt
>     mask rather than enabling/disabling the system interrupt. This cleans
>     up the driver so that it doesn't rely on interrupts being disabled
>     within the interrupt handler.
>     For i.MX21 we keep the current behaviour, that is calling
>     enable_irq/disable_irq_nosync to enable/disable interrupts.
>     This patch is based on earlier work by John Ogness.

Acked-by: John Ogness <john.ogness@linutronix.de>    

>     Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

[PATCH 1/3] mxc_nand: set spare size and pages per block

[Sascha Hauer]

On Mon, Aug 16, 2010 at 02:05:44PM +0200, John Ogness wrote:
> On 2010-08-16, Sascha Hauer <s.hauer@pengutronix.de> wrote:
> > Ok, here is an updated version of this patch
> >
> > Sascha
> >
> > commit 3a411e6c690654f78bea93dd8cdb14c27ba418a5
> > Author: Sascha Hauer <s.hauer@pengutronix.de>
> > Date:   Mon Aug 9 14:21:00 2010 +0200
> >
> >     mxc_nand: do not depend on disabling the irq in the interrupt handler
> >     
> >     This patch reverts the driver to enabling/disabling the NFC interrupt
> >     mask rather than enabling/disabling the system interrupt. This cleans
> >     up the driver so that it doesn't rely on interrupts being disabled
> >     within the interrupt handler.
> >     For i.MX21 we keep the current behaviour, that is calling
> >     enable_irq/disable_irq_nosync to enable/disable interrupts.
> >     This patch is based on earlier work by John Ogness.
> 
> Acked-by: John Ogness <john.ogness@linutronix.de>    

Can I consider this as an Acked-by for the whole series? And since you
tested it I would also add a tested-by. Here is a summary of the series
again:


The following changes since commit da5cabf80e2433131bf0ed8993abc0f7ea618c73:

  Linux 2.6.36-rc1 (2010-08-15 17:41:37 -0700)

are available in the git repository at:
  git://git.pengutronix.de/git/imx/linux-2.6.git mxc-nand-pu

John Ogness (2):
      mxc_nand: Do not do byte accesses to the NFC buffer.
      mxc_nand: remove unused variables.

Sascha Hauer (10):
      mxc_nand: remove 0xe00 offset from registers
      mxc_nand: rework get_dev_status
      mxc_nand: make some internally used functions overwriteable
      mxc_nand: factor out a check_int function
      mxc_nand: add V1_V2 namespace to registers
      mxc_nand: support 8bit ecc
      mxc_nand: fix correct_data function
      mxc_nand: Add v3 (i.MX51) Support
      mxc_nand: do not depend on disabling the irq in the interrupt handler
      mxc_nand: configure pages per block for v2 controller

 drivers/mtd/nand/Kconfig    |    2 +-
 drivers/mtd/nand/mxc_nand.c |  671 +++++++++++++++++++++++++++++++++----------
 2 files changed, 521 insertions(+), 152 deletions(-)

Sascha

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

[PATCH 1/3] mxc_nand: set spare size and pages per block

[John Ogness]

On 2010-08-17, Sascha Hauer <s.hauer@pengutronix.de> wrote:
> The following changes since commit da5cabf80e2433131bf0ed8993abc0f7ea618c73:
>
>   Linux 2.6.36-rc1 (2010-08-15 17:41:37 -0700)
>
> are available in the git repository at:
>   git://git.pengutronix.de/git/imx/linux-2.6.git mxc-nand-pu
>
> John Ogness (2):
>       mxc_nand: Do not do byte accesses to the NFC buffer.
>       mxc_nand: remove unused variables.
>
> Sascha Hauer (10):
>       mxc_nand: remove 0xe00 offset from registers
>       mxc_nand: rework get_dev_status
>       mxc_nand: make some internally used functions overwriteable
>       mxc_nand: factor out a check_int function
>       mxc_nand: add V1_V2 namespace to registers
>       mxc_nand: support 8bit ecc
>       mxc_nand: fix correct_data function
>       mxc_nand: Add v3 (i.MX51) Support
>       mxc_nand: do not depend on disabling the irq in the interrupt handler
>       mxc_nand: configure pages per block for v2 controller
>
>  drivers/mtd/nand/Kconfig    |    2 +-
>  drivers/mtd/nand/mxc_nand.c |  671 +++++++++++++++++++++++++++++++++----------
>  2 files changed, 521 insertions(+), 152 deletions(-)

Acked-by: John Ogness <john.ogness@linutronix.de>
Tested-by: John Ogness <john.ogness@linutronix.de>

I tested the driver with all the above changes on an i.MX35 with a
16-bit NAND chip. The driver performed as expected.

[PATCH 1/3] mxc_nand: set spare size and pages per block

[Artem Bityutskiy]

On Tue, 2010-08-10 at 13:34 +0200, John Ogness wrote:
> This patch sets the NFC registers for spare size and pages per block.
> 
> This patch is against the latest patches from Sascha Hauer.
> 
> Signed-off-by: John Ogness <john.ogness@linutronix.de>
> ---
>  drivers/mtd/nand/mxc_nand.c |   32 ++++++++++++++++++++++++++++++++
>  1 file changed, 32 insertions(+)

I'm not picking your patches and assume they'll be sent by Sascha.

-- 
Best Regards,
Artem Bityutskiy (???????? ?????)