Re: [PATCH] usb: gadget: aspeed: fixup vhub port irq handling
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From: Felipe Balbi <balbi@kernel.org>
Date: 2020-08-17 13:49:48
Also in:
linux-aspeed, linux-usb, lkml, openbmc
Hi, rentao.bupt@gmail.com writes:
quoted hunk ↗ jump to hunk
From: Tao Ren <redacted> This is a follow-on patch for commit a23be4ed8f48 ("usb: gadget: aspeed: improve vhub port irq handling"): for_each_set_bit() is replaced with simple for() loop because for() loop runs faster on ASPEED BMC. Signed-off-by: Tao Ren <redacted> --- drivers/usb/gadget/udc/aspeed-vhub/core.c | 10 +++------- drivers/usb/gadget/udc/aspeed-vhub/vhub.h | 3 +++ 2 files changed, 6 insertions(+), 7 deletions(-)diff --git a/drivers/usb/gadget/udc/aspeed-vhub/core.c b/drivers/usb/gadget/udc/aspeed-vhub/core.c index cdf96911e4b1..be7bb64e3594 100644 --- a/drivers/usb/gadget/udc/aspeed-vhub/core.c +++ b/drivers/usb/gadget/udc/aspeed-vhub/core.c@@ -135,13 +135,9 @@ static irqreturn_t ast_vhub_irq(int irq, void *data) /* Handle device interrupts */ if (istat & vhub->port_irq_mask) { - unsigned long bitmap = istat; - int offset = VHUB_IRQ_DEV1_BIT; - int size = VHUB_IRQ_DEV1_BIT + vhub->max_ports; - - for_each_set_bit_from(offset, &bitmap, size) { - i = offset - VHUB_IRQ_DEV1_BIT; - ast_vhub_dev_irq(&vhub->ports[i].dev); + for (i = 0; i < vhub->max_ports; i++) { + if (istat & VHUB_DEV_IRQ(i)) + ast_vhub_dev_irq(&vhub->ports[i].dev);
how have you measured your statement above? for_each_set_bit() does exactly what you did. Unless your architecture has an instruction which helps finds the next set bit (like cls on ARM), which, then, makes it much faster. -- balbi