Hi,

From: Thomas Gleixner [mailto:tglx at linutronix.de]
Sent: Wednesday, March 02, 2011 3:15 AM

quoted

+
+static DEFINE_SPINLOCK(lock);
+static struct clk *pruss_clk;
+static struct uio_info *info;
+static dma_addr_t sram_paddr, ddr_paddr;
+static void *prussio_vaddr, *sram_vaddr, *ddr_vaddr;
+
+static irqreturn_t pruss_handler(int irq, struct uio_info *info)
+{
+	int intr_bit = (irq - IRQ_DA8XX_EVTOUT0 + 2);
+	int val, intr_mask = (1 << intr_bit);
+	void __iomem *base = info->mem[0].internal_addr;
+	void __iomem *intren_reg = base + PINTC_HIER;
+	void __iomem *intrstat_reg = base + PINTC_HIPIR + (intr_bit << 2);
+
+	spin_lock_irq(&lock);

No, I said: spin_lock() is sufficient.

Ok. 

quoted

+	val = ioread32(intren_reg);
+	/* Is interrupt enabled and active ? */
+	if (!(val & intr_mask) && (ioread32(intrstat_reg) & HIPIR_NOPEND)) {
+		spin_unlock_irq(&lock);

You unconditinally enable interrupts here where you are not supposed
to do so.

Ok.

quoted

+		return IRQ_NONE;
+	}
+
+	/* Disable interrupt */
+	iowrite32((val & ~intr_mask), intren_reg);

I checked more on this and actually INTC h/w has Host Interrupt
Enable Indexed Set Register (HIEISR) and Host Interrupt Enable Indexed
Clear Register(HIEICR) which I can use to enable/disable interrupts
without doing RMW. I will use these registers and then we don't need
all the spinlock and irqcontrol stuff. So I need to do

iowrite32((intr_bit, HIEICR);// This disable the interrupt bit
in intern_reg.

Userspace can use HIEISR to re-enable the interrupt.

quoted

+	spin_unlock_irq(&lock);
+	return IRQ_HANDLED;
+}
+
+static int pruss_irqcontrol(struct uio_info *info, s32 irq_on)
+{
+	int intr_bit = info->irq - IRQ_DA8XX_EVTOUT0 + 2;
+	int val, intr_mask = (1 << intr_bit);
+	void __iomem *base = info->mem[0].internal_addr;
+	void __iomem *intren_reg = base + PINTC_HIER;
+
+	spin_lock_irq(&lock);

This one is correct, as this is always called from non interrupt
disabled context.

quoted

+	val = ioread32(intren_reg);
+	if (irq_on)
+		iowrite32((val | intr_mask), intren_reg);
+	else
+		iowrite32((val & ~intr_mask), intren_reg);
+	spin_unlock_irq(&lock);
+
+	return 0;
+}

quoted

+
+	spin_lock_init(&lock);

Sigh. DEFINE_SPINLOCK(lock); already initializes the lock.

It's not the purpose of a review to tell you what you need to change
mechanically. Reviewers hint to a correct solution and you are
supposed to lookup what that solution means and act accordingly. If
you do not understand the hint or its implications please ask _before_
sending a new patch set.

Seriously, I went to "fix the comments" mode. Sorry about that. Anyway
I learnt more about things by making mistakes i.e. the positive side.
Thanks a lot for helping us improve on this. 

Pratheesh