linux-kernel - Re: [PATCH v2] usb: gadget: aspeed: improve vhub port irq handling

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Date:   Wed, 11 Mar 2020 12:31:22 +1100
From:   Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:     rentao.bupt@...il.com, Felipe Balbi <balbi@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Joel Stanley <joel@....id.au>,
        Andrew Jeffery <andrew@...id.au>,
        Chunfeng Yun <chunfeng.yun@...iatek.com>,
        Stephen Boyd <swboyd@...omium.org>, linux-usb@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-aspeed@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        openbmc@...ts.ozlabs.org, taoren@...com
Subject: Re: [PATCH v2] usb: gadget: aspeed: improve vhub port irq handling

On Thu, 2020-03-05 at 15:47 -0800, rentao.bupt@...il.com wrote:
> From: Tao Ren <rentao.bupt@...il.com>
> 
> This patch evaluates vhub ports' irq mask before going through per-port
> irq handling one by one, which helps to speed up irq handling in case
> there is no port interrupt.
> 
> Signed-off-by: Tao Ren <rentao.bupt@...il.com>
> ---
>  Changes in v2:
>    - use "for_each_set_bit" to speed up port irq handling.
> 
>  drivers/usb/gadget/udc/aspeed-vhub/core.c | 11 ++++++++---
>  drivers/usb/gadget/udc/aspeed-vhub/vhub.h |  8 +++-----
>  2 files changed, 11 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/usb/gadget/udc/aspeed-vhub/core.c b/drivers/usb/gadget/udc/aspeed-vhub/core.c
> index f8d35dd60c34..af2dbd405361 100644
> --- a/drivers/usb/gadget/udc/aspeed-vhub/core.c
> +++ b/drivers/usb/gadget/udc/aspeed-vhub/core.c
> @@ -134,11 +134,14 @@ static irqreturn_t ast_vhub_irq(int irq, void *data)
>  	}
>  
>  	/* Handle device interrupts */
> -	for (i = 0; i < vhub->max_ports; i++) {
> -		u32 dev_mask = VHUB_IRQ_DEVICE1 << i;
> +	if (istat & vhub->port_irq_mask) {
> +		int offset = VHUB_IRQ_DEV1_BIT;
> +		int size = VHUB_IRQ_DEV1_BIT + vhub->max_ports;
>  
> -		if (istat & dev_mask)
> +		for_each_set_bit_from(offset, (unsigned long *)&istat, size) 

That type cast is very bad. It will not work on big endian for example
(yes this driver isn't used on big endian today but still).

Please assign istat to an unsigned long (or make it unsigned long to
begin with).

> +			i = offset - VHUB_IRQ_DEV1_BIT;
>  			ast_vhub_dev_irq(&vhub->ports[i].dev);
> +		}
>  	}
>  
>  	/* Handle top-level vHub EP0 interrupts */
> @@ -332,6 +335,8 @@ static int ast_vhub_probe(struct platform_device *pdev)
>  
>  	spin_lock_init(&vhub->lock);
>  	vhub->pdev = pdev;
> +	vhub->port_irq_mask = GENMASK(VHUB_IRQ_DEV1_BIT + vhub->max_ports - 1,
> +				      VHUB_IRQ_DEV1_BIT);
>  
>  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>  	vhub->regs = devm_ioremap_resource(&pdev->dev, res);
> diff --git a/drivers/usb/gadget/udc/aspeed-vhub/vhub.h b/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
> index fac79ef6d669..23a1ac91f8d2 100644
> --- a/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
> +++ b/drivers/usb/gadget/udc/aspeed-vhub/vhub.h
> @@ -51,14 +51,11 @@
>  #define VHUB_CTRL_UPSTREAM_CONNECT		(1 << 0)
>  
>  /* IER & ISR */
> +#define VHUB_IRQ_DEV1_BIT			9
>  #define VHUB_IRQ_USB_CMD_DEADLOCK		(1 << 18)
>  #define VHUB_IRQ_EP_POOL_NAK			(1 << 17)
>  #define VHUB_IRQ_EP_POOL_ACK_STALL		(1 << 16)
> -#define VHUB_IRQ_DEVICE5			(1 << 13)
> -#define VHUB_IRQ_DEVICE4			(1 << 12)
> -#define VHUB_IRQ_DEVICE3			(1 << 11)
> -#define VHUB_IRQ_DEVICE2			(1 << 10)
> -#define VHUB_IRQ_DEVICE1			(1 << 9)
> +#define VHUB_IRQ_DEVICE1			(1 << (VHUB_IRQ_DEV1_BIT))
>  #define VHUB_IRQ_BUS_RESUME			(1 << 8)
>  #define VHUB_IRQ_BUS_SUSPEND 			(1 << 7)
>  #define VHUB_IRQ_BUS_RESET 			(1 << 6)
> @@ -402,6 +399,7 @@ struct ast_vhub {
>  	/* Per-port info */
>  	struct ast_vhub_port		*ports;
>  	u32				max_ports;
> +	u32				port_irq_mask;
>  
>  	/* Generic EP data structures */
>  	struct ast_vhub_ep		*epns;