Subject: [PATCH v3 1/2] mtd: nand: pxa3xx: Fix PIO FIFO draining

From: [email-masked] (Maxime Ripard)
Date: Tue, 17 Feb 2015 11:37:40 +0100

On Mon, Feb 16, 2015 at 10:36:02PM +0100, Robert Jarzmik wrote:
> diff --git a/drivers/mtd/nand/pxa3xx_nand.c b/drivers/mtd/nand/pxa3xx_nand.c
> index e512902..6e569e9 100644
> --- a/drivers/mtd/nand/pxa3xx_nand.c
> +++ b/drivers/mtd/nand/pxa3xx_nand.c
> @@ -576,11 +576,20 @@ static void start_data_dma(struct pxa3xx_nand_info *info)
>  {}
>  #endif
>  
> +static irqreturn_t pxa3xx_nand_irq_thread(int irq, void *data)
> +{
> +	struct pxa3xx_nand_info *info = data;
> +
> +	handle_data_pio(info);
> +	return IRQ_HANDLED;
> +}
> +
>  static irqreturn_t pxa3xx_nand_irq(int irq, void *devid)
>  {
>  	struct pxa3xx_nand_info *info = devid;
>  	unsigned int status, is_completed = 0, is_ready = 0;
>  	unsigned int ready, cmd_done;
> +	irqreturn_t ret = IRQ_HANDLED;
>  
>  	if (info->cs == 0) {
>  		ready           = NDSR_FLASH_RDY;
> @@ -622,7 +631,7 @@ static irqreturn_t pxa3xx_nand_irq(int irq, void *devid)
>  		} else {
>  			info->state = (status & NDSR_RDDREQ) ?
>  				      STATE_PIO_READING : STATE_PIO_WRITING;
> -			handle_data_pio(info);
> +			ret = IRQ_WAKE_THREAD;
>  		}
>  	}
>  	if (status & cmd_done) {
> @@ -663,7 +672,7 @@ static irqreturn_t pxa3xx_nand_irq(int irq, void *devid)
>  	if (is_ready)
>  		complete(&info->dev_ready);
>  NORMAL_IRQ_EXIT:
> -	return IRQ_HANDLED;
> +	return ret;
>  }
>  
>  static inline int is_buf_blank(uint8_t *buf, size_t len)
> @@ -1688,7 +1697,8 @@ static int alloc_nand_resource(struct platform_device *pdev)
>  	/* initialize all interrupts to be disabled */
>  	disable_int(info, NDSR_MASK);
>  
> -	ret = request_irq(irq, pxa3xx_nand_irq, 0, pdev->name, info);
> +	ret = request_threaded_irq(irq, pxa3xx_nand_irq,
> +				   pxa3xx_nand_irq_thread, 0, pdev->name, info);
>  	if (ret < 0) {
>  		dev_err(&pdev->dev, "failed to request IRQ\n");
>  		goto fail_free_buf;

I just gave this patch a try, and it blows up quite badly:
http://code.bulix.org/p96krc-87889?raw

It looks like there's more work here, most likely in the waitqueues
wake up.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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