Re: [PATCH v3 6/8] drm/panfrost: Convert MMU IRQ handler to threaded handler

From: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
To: Rob Herring <robh@kernel.org>
Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>,
	Maxime Ripard <maxime.ripard@bootlin.com>,
	Sean Paul <sean@poorly.run>,
	dri-devel@lists.freedesktop.org,
	Steven Price <steven.price@arm.com>,
	David Airlie <airlied@linux.ie>,
	Boris Brezillon <boris.brezillon@collabora.com>,
	Robin Murphy <robin.murphy@arm.com>
Subject: Re: [PATCH v3 6/8] drm/panfrost: Convert MMU IRQ handler to threaded handler
Date: Fri, 2 Aug 2019 15:28:14 -0700	[thread overview]
Message-ID: <20190802222814.GA15297@kevin> (raw)
In-Reply-To: <20190802195150.23207-7-robh@kernel.org>


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A-b, I think.

On Fri, Aug 02, 2019 at 01:51:48PM -0600, Rob Herring wrote:
> In preparation to handle mapping of page faults, we need the MMU handler
> to be threaded as code paths take a mutex.
> 
> As the IRQ may be shared, we can't use the default handler and must
> disable the MMU interrupts locally.
> 
> Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
> Cc: Boris Brezillon <boris.brezillon@collabora.com>
> Cc: Robin Murphy <robin.murphy@arm.com>
> Cc: Steven Price <steven.price@arm.com>
> Cc: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
> Signed-off-by: Rob Herring <robh@kernel.org>
> ---
>  drivers/gpu/drm/panfrost/panfrost_mmu.c | 20 +++++++++++++++-----
>  1 file changed, 15 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c
> index eba6ce785ef0..7d44328b280f 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_mmu.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c
> @@ -300,12 +300,20 @@ static const char *access_type_name(struct panfrost_device *pfdev,
>  static irqreturn_t panfrost_mmu_irq_handler(int irq, void *data)
>  {
>  	struct panfrost_device *pfdev = data;
> -	u32 status = mmu_read(pfdev, MMU_INT_STAT);
> -	int i;
>  
> -	if (!status)
> +	if (!mmu_read(pfdev, MMU_INT_STAT))
>  		return IRQ_NONE;
>  
> +	mmu_write(pfdev, MMU_INT_MASK, 0);
> +	return IRQ_WAKE_THREAD;
> +}
> +
> +static irqreturn_t panfrost_mmu_irq_handler_thread(int irq, void *data)
> +{
> +	struct panfrost_device *pfdev = data;
> +	u32 status = mmu_read(pfdev, MMU_INT_RAWSTAT);
> +	int i;
> +
>  	dev_err(pfdev->dev, "mmu irq status=%x\n", status);
>  
>  	for (i = 0; status; i++) {
> @@ -350,6 +358,7 @@ static irqreturn_t panfrost_mmu_irq_handler(int irq, void *data)
>  		status &= ~mask;
>  	}
>  
> +	mmu_write(pfdev, MMU_INT_MASK, ~0);
>  	return IRQ_HANDLED;
>  };
>  
> @@ -368,8 +377,9 @@ int panfrost_mmu_init(struct panfrost_device *pfdev)
>  	if (irq <= 0)
>  		return -ENODEV;
>  
> -	err = devm_request_irq(pfdev->dev, irq, panfrost_mmu_irq_handler,
> -			       IRQF_SHARED, "mmu", pfdev);
> +	err = devm_request_threaded_irq(pfdev->dev, irq, panfrost_mmu_irq_handler,
> +					panfrost_mmu_irq_handler_thread,
> +					IRQF_SHARED, "mmu", pfdev);
>  
>  	if (err) {
>  		dev_err(pfdev->dev, "failed to request mmu irq");
> -- 
> 2.20.1
> 

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