On Tue, Feb 17, 2015 at 09:06:57PM +0100, Robert Jarzmik wrote: > Change the handling of the data stage in the driver : don't pump data in > the top-half interrupt, but rather schedule a thread for non dma cases. > > This will enable latencies in the data pumping, especially if delays are > required. Moreover platform shall be more reactive as other interrupts > can be served while pumping data. > > No throughput degradation was observed, at least on the zylonite > platform, while a slight degradation was being expected. > > Signed-off-by: Robert Jarzmik <robert.jarz...@free.fr>
Tested-by: Maxime Ripard <maxime.rip...@free-electrons.com>
On a sidenote...
> ---
> drivers/mtd/nand/pxa3xx_nand.c | 23 ++++++++++++++++++++---
> 1 file changed, 20 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/mtd/nand/pxa3xx_nand.c b/drivers/mtd/nand/pxa3xx_nand.c
> index 96b0b1d..237c92c 100644
> --- a/drivers/mtd/nand/pxa3xx_nand.c
> +++ b/drivers/mtd/nand/pxa3xx_nand.c
> @@ -569,11 +569,25 @@ 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);
> +
> + info->state = STATE_CMD_DONE;
> + nand_writel(info, NDSR, NDSR_WRDREQ | NDSR_RDDREQ);
> + enable_int(info, NDCR_INT_MASK);
> +
> + 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;
> @@ -613,9 +627,11 @@ static irqreturn_t pxa3xx_nand_irq(int irq, void *devid)
> start_data_dma(info);
> goto NORMAL_IRQ_EXIT;
> } else {
> + disable_int(info, NDCR_INT_MASK);
> info->state = (status & NDSR_RDDREQ) ?
> STATE_PIO_READING : STATE_PIO_WRITING;
> - handle_data_pio(info);
> + ret = IRQ_WAKE_THREAD;
> + goto NORMAL_IRQ_EXIT;
> }
> }
> if (status & cmd_done) {
> @@ -656,7 +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)
> @@ -1672,7 +1688,8 @@ 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);
Using IRQF_ONESHOT would allow you not to do the interrupt enable /
disable dance.
Maxime
--
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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