| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <807hloag6w.fsf@merkur.tec.linutronix.de>
Date: Thu, 24 Jun 2010 12:16:39 +0200
From: John Ogness <john.ogness@...utronix.de>
To: Sascha Hauer <s.hauer@...gutronix.de>
Cc: Ivo Clarysse <ivo.clarysse@...il.com>,
Sascha Hauer <kernel@...gutronix.de>,
linux-arm-kernel@...ts.infradead.org,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCHv3 4/5] mtd: mxc_nand fixups
On 2010-06-24, Sascha Hauer <s.hauer@...gutronix.de> wrote:
> Ok, if it's the only way out to have 5 cpu_is_* blocks, then lets go
> for it.
Here is a new patch that puts the behavior behind a "nfc_avoid_masking"
macro. The macro is only used 3 times.
I also changed the code to use a completion, since that's exactly what
we are doing there anyway.
I also added some other macros to simplify reading of the code and
reduce possible copy/paste errors relating to masking and interrupt
handling.
> BTW I observed that at least on i.MX27 the latencies introduced by
> waiting for an interrupt cause a significant performance drop. The
> driver gets much faster when we just poll all the time. I don't know
> how this affects system performance otherwise, but it may be a
> possibility to drop interrupt support at least for i.MX21. I have no
> idea how long the longest possible time we'd have to poll is though.
I don't recommend moving to pure polling. Although it may be faster for
NAND-only performance tests, I expect it would have a dramatic affect on
the rest of the system during many NAND reads/writes.
This patch is based on linux-next 20100618.
Signed-off-by: John Ogness <john.ogness@...utronix.de>
---
drivers/mtd/nand/mxc_nand.c | 81 +++++++++++++++++++++++++---------
1 file changed, 61 insertions(+), 20 deletions(-)
Index: linux-next-20100618/drivers/mtd/nand/mxc_nand.c
===================================================================
--- linux-next-20100618.orig/drivers/mtd/nand/mxc_nand.c
+++ linux-next-20100618/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>
@@ -40,6 +42,13 @@
#define nfc_is_v21() (cpu_is_mx25() || cpu_is_mx35())
#define nfc_is_v1() (cpu_is_mx31() || cpu_is_mx27() || cpu_is_mx21())
+/* It has been observeed 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. 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_BUF_SIZE 0xE00
#define NFC_BUF_ADDR 0xE04
@@ -100,6 +109,18 @@
#define NFC_RSLTSPARE_AREA_MASK 0xff
+#define nfc_interrupt_set(_regs) \
+ (readw(_regs + NFC_CONFIG2) & NFC_INT)
+#define nfc_clear_interrupt(_regs) \
+ writew(readw(_regs + NFC_CONFIG2) & ~NFC_INT, \
+ _regs + NFC_CONFIG2)
+#define nfc_mask_irq(_regs) \
+ writew(readw(_regs + NFC_CONFIG1) | NFC_INT_MSK, \
+ _regs + NFC_CONFIG1)
+#define nfc_unmask_irq(_regs) \
+ writew(readw(_regs + NFC_CONFIG1) & ~NFC_INT_MSK, \
+ _regs + NFC_CONFIG1)
+
struct mxc_nand_host {
struct mtd_info mtd;
struct nand_chip nand;
@@ -117,7 +138,7 @@ struct mxc_nand_host {
int clk_act;
int irq;
- wait_queue_head_t irq_waitq;
+ struct completion op_completion;
uint8_t *data_buf;
unsigned int buf_start;
@@ -174,9 +195,18 @@ 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 (!nfc_interrupt_set(host->regs))
+ 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. */
+ nfc_mask_irq(host->regs);
+
+ /* Notify the driver thread that an interrupt has occurred.
+ * The driver thread will clear the interrupt. */
+ complete(&host->op_completion);
return IRQ_HANDLED;
}
@@ -186,27 +216,32 @@ static irqreturn_t mxc_nfc_irq(int irq,
*/
static void wait_op_done(struct mxc_nand_host *host, int useirq)
{
- uint16_t tmp;
int max_retries = 8000;
if (useirq) {
- if ((readw(host->regs + NFC_CONFIG2) & NFC_INT) == 0) {
+ if (!nfc_interrupt_set(host->regs)) {
+
+ INIT_COMPLETION(host->op_completion);
- enable_irq(host->irq);
+ if (nfc_avoid_masking())
+ enable_irq(host->irq);
+ else
+ nfc_unmask_irq(host->regs);
- wait_event(host->irq_waitq,
- readw(host->regs + NFC_CONFIG2) & NFC_INT);
+ /* wait for the interrupt */
+ wait_for_completion(&host->op_completion);
- tmp = readw(host->regs + NFC_CONFIG2);
- tmp &= ~NFC_INT;
- writew(tmp, host->regs + NFC_CONFIG2);
+ if (nfc_avoid_masking()) {
+ disable_irq(host->irq);
+ nfc_unmask_irq(host->regs);
+ }
}
+
+ nfc_clear_interrupt(host->regs);
} else {
while (max_retries-- > 0) {
- if (readw(host->regs + NFC_CONFIG2) & NFC_INT) {
- tmp = readw(host->regs + NFC_CONFIG2);
- tmp &= ~NFC_INT;
- writew(tmp, host->regs + NFC_CONFIG2);
+ if (nfc_interrupt_set(host->regs)) {
+ nfc_clear_interrupt(host->regs);
break;
}
udelay(1);
@@ -582,9 +617,8 @@ static void preset(struct mtd_info *mtd)
struct mxc_nand_host *host = nand_chip->priv;
uint16_t tmp;
- /* enable interrupt, disable spare enable, setup ECC */
+ /* disable spare-only, setup ECC */
tmp = readw(host->regs + NFC_CONFIG1);
- tmp &= ~NFC_INT_MSK;
tmp &= ~NFC_SP_EN;
if (nand_chip->ecc.mode == NAND_ECC_HW) {
tmp |= NFC_ECC_EN;
@@ -842,11 +876,18 @@ 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);
+ nfc_unmask_irq(host->regs);
+ } else {
+ nfc_mask_irq(host->regs);
+ }
+
+ err = request_irq(host->irq, mxc_nfc_irq, 0, DRIVER_NAME, host);
if (err)
goto eirq;
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists