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SubjectRe: [PATCH v3 1/2] mtd: nand: pxa3xx: Fix PIO FIFO draining
On 02/17/2015 02:07 PM, Robert Jarzmik wrote:
> Maxime Ripard <maxime.ripard@free-electrons.com> writes:
>
>> 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
> Confirmed.
> OTOH, replacing :
>>> + ret = IRQ_WAKE_THREAD;
> With:
> + ret = IRQ_WAKE_THREAD;
> + goto NORMAL_IRQ_EXIT;
>
> is fully working in my environment, now I got 10mn to test it.
> I also added for cosmetics in pxa3xx_nand_irq_thread() a :
> info->state = STATE_CMD_DONE;
>
>> It looks like there's more work here, most likely in the waitqueues
>> wake up.
> Not that much if I'm right, hein ?
> And it enables the msleep() instead of mdelay().
>
> And the flow of the driver is not changed for pxa3xx, only for Armada (ie. non
> dma case) for which you need to introduce a delay anyway, and therefore change
> the flow.
>
> It will be Brian choice eventually, but if you say that you will submit that
> approach for next cycle, and yours for stable, and that for next you'll convert
> mdelay() to msleep(), I'll stop arguing.
>

How about you push a proper patchset with this alternative (and a nice
cover letter explaining the need for a threaded irq) so we can discuss
properly this new turn?

--
Ezequiel García, Free Electrons
Embedded Linux, Kernel and Android Engineering
http://free-electrons.com


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