[PATCH] staging: nvec: move to use request_irq by IRQF_NO_AUTOEN flag

[PATCH] staging: nvec: move to use request_irq by IRQF_NO_AUTOEN flag

[Tian Tao]

disable_irq() after request_irq() still has a time gap in which
interrupts can come. request_irq() with IRQF_NO_AUTOEN flag will
disable IRQ auto-enable because of requesting.

this patch is made base on "add IRQF_NO_AUTOEN for request_irq" which
is being merged: https://lore.kernel.org/patchwork/patch/1388765/

Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
---
 drivers/staging/nvec/nvec.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/nvec/nvec.c b/drivers/staging/nvec/nvec.c
index a80996b..f23e127 100644
--- a/drivers/staging/nvec/nvec.c
+++ b/drivers/staging/nvec/nvec.c
@@ -831,13 +831,12 @@ static int tegra_nvec_probe(struct platform_device *pdev)
 		return PTR_ERR(nvec->gpiod);
 	}
 
-	err = devm_request_irq(dev, nvec->irq, nvec_interrupt, 0,
-			       "nvec", nvec);
+	err = devm_request_irq(dev, nvec->irq, nvec_interrupt,
+			       IRQF_NO_AUTOEN, "nvec", nvec);
 	if (err) {
 		dev_err(dev, "couldn't request irq\n");
 		return -ENODEV;
 	}
-	disable_irq(nvec->irq);
 
 	tegra_init_i2c_slave(nvec);
 
-- 
2.7.4

Re: [PATCH] staging: nvec: move to use request_irq by IRQF_NO_AUTOEN flag

[Michał Mirosław]

On Wed, Apr 07, 2021 at 02:34:19PM +0800, Tian Tao wrote:
> disable_irq() after request_irq() still has a time gap in which
> interrupts can come. request_irq() with IRQF_NO_AUTOEN flag will
> disable IRQ auto-enable because of requesting.
> 
> this patch is made base on "add IRQF_NO_AUTOEN for request_irq" which
> is being merged: https://lore.kernel.org/patchwork/patch/1388765/

This assumes that the interrupt is not shared. This could be fixed
by requesting the IRQ after init (and releasing before deinit).

Best Regards
Michał Mirosław

Re: [PATCH] staging: nvec: move to use request_irq by IRQF_NO_AUTOEN flag

[Marc Dietrich]

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Hi,

On Thu, 8 Apr 2021, Michał Mirosław wrote:

> On Wed, Apr 07, 2021 at 02:34:19PM +0800, Tian Tao wrote:
>> disable_irq() after request_irq() still has a time gap in which
>> interrupts can come. request_irq() with IRQF_NO_AUTOEN flag will
>> disable IRQ auto-enable because of requesting.
>>
>> this patch is made base on "add IRQF_NO_AUTOEN for request_irq" which
>> is being merged: https://lore.kernel.org/patchwork/patch/1388765/

thanks for you patch, Tao, which look good to me.

> This assumes that the interrupt is not shared. This could be fixed
> by requesting the IRQ after init (and releasing before deinit).

Michał, I understand your objections, and for the general case you are 
right. However, I think it would be good to keep the structure as close 
as possible to i2c-tegra [1], which does the same as Tao suggested. I'm 
also pretty sure that the interrupt is not shared on this (single) machine 
which this driver is made for.
So unless there are some strong arguments aginst it, I personally perfer 
his version.

Best wishes,

Marc Dietrich

[1] 
https://github.com/torvalds/linux/blob/17e7124aad766b3f158943acb51467f86220afe9/drivers/i2c/busses/i2c-tegra.c#L1740

Re: [PATCH] staging: nvec: move to use request_irq by IRQF_NO_AUTOEN flag

[Marc Dietrich]

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Hi,

On Thu, 8 Apr 2021, Michał Mirosław wrote:

> On Wed, Apr 07, 2021 at 02:34:19PM +0800, Tian Tao wrote:
>> disable_irq() after request_irq() still has a time gap in which
>> interrupts can come. request_irq() with IRQF_NO_AUTOEN flag will
>> disable IRQ auto-enable because of requesting.
>>
>> this patch is made base on "add IRQF_NO_AUTOEN for request_irq" which
>> is being merged: https://lore.kernel.org/patchwork/patch/1388765/

thanks for you patch, Tao, which look good to me.

> This assumes that the interrupt is not shared. This could be fixed
> by requesting the IRQ after init (and releasing before deinit).

Michał, I understand your objections, and for the general case you are 
right. However, I think it would be good to keep the structure as close 
as possible to i2c-tegra [1], which does the same as Tao suggested. I'm 
also pretty sure that the interrupt is not shared on this (single) machine 
which this driver is made for.
So unless there are some strong arguments aginst it, I personally perfer 
his version.

Best wishes,

Marc Dietrich

[1] 
https://github.com/torvalds/linux/blob/17e7124aad766b3f158943acb51467f86220afe9/drivers/i2c/busses/i2c-tegra.c#L1740